See also: Related OurFood News
Subsections
Modern packaging protects food, increasing shelf live and safety. It also makes distribution possible over long distances. Its closures are made to avoid any undesired alterations after production. This includes safety seals
and other devices to show any criminal poisoning of food by blackmailer.
The best packaging is glass because of its chemical stability. Industry tries to change glass by one-way packages made of glass because of price and weight.
Glass is one hundred percent barrier against oxygen. Glass however can break. The small splinters being undetected present a great hazard to consumers. The industry spends great efforts to avoid any fragmentation.
Tin cans are widely used for packaging of pasteurized and sterilized food. They present corrosion with acid medium. Zink, iron and all other metal ions are increasing in food, leaching out of the packaging material. Many poisoning cases were caused by the use of zinc bowls.
Metal ions were drastically reduced by internal coating the cans with layers of varnish. The wrong varnish can also create a high level of BADGE (see this
topic).
Small cracks of the varnish layer can cause black dots when chicken meat is present. The iron of the can reacts with the sulphur of the protein molecules of the
resulting iron sulfide. Quality inspection of the varnish coating is therefore very important.
Packaging made of plastics present new advantages. There are rigid and flexible packages. Flexible packages may present active and barrier properties. This is used for meat packaging. At first the package acts actively to get rid of excessive moisture and works then as a barrier against oxygen.[1]
The UK Food Standards Agency (FSA)reported in a Food Survey Information Sheet (FSIS) of 2002 that tin in canned fruit and vegetables revealed that all but two of four hundred retail samples tested contained tin at levels below the regulatory limit of 200 mg/kg set by the UK Tin in Food Regulations 1992. One sample of spaghetti in tomato sauce and one sample of gooseberries were found to be above this limit.
The retailers/suppliers recalled affected batches. The FSIS concluded that there are no long term food safety concerns for consumers and no chronic health effects from tin concentration in food are expected. Chronic health effects are not expected even at elevated tin concentrations found in the FSIS survey of 2002. [2]
Tin can leach from tin can into food in a concentration between 100-500 ppm whereas tin content in normal food is about 1 ppm, varying according to the levels of the element in soil. Internal coating the cans with layers of varnish improved the situation.
In a review of 2003 Blunder and Wallace found some evidence suggesting that tin concentrations at or below 200 ppm has caused adverse gastrointestinal effects, however these data were of uncertain veracity. Some studies observed gastrointestinal effects at concentrations of 700 ppm or above, other studies reported no effects at even higher concentrations. Based on the fact that no acute effects of tin contamination in the range 100-200 ppm occurred during the last 25 years, the authors concluded that the consumption of food containing tin at concentrations up to 200 ppm is considered to be safe. [3]
The Provisional Tolerable Weekly Intake for tin is 14 mg/kg body weight and recommended maximum permissible levels of tin in food are typically 250 mg/kg (200 mg/kg UK) for solid foods and 150 mg/kg for beverages. [2]
Quercetin
Dehghan and Khoshkam 2011 suggest the use of quercentin to reduce elevated levels of tin in foods. Quercentin is a chelating agent which binds to the tin and improves excretion from the body. Other effects of quercetin regarding health benefits, such as cardiovascular protection, anticancer, antiulcer, antiallergic, antioxidant, antiviral and anti-inflammatory potentials are not confirmed yet. [4]
Heat treatment after packaging kills microbes and improves shelf-life. Different technologies and packaging materials such as tin, carton, greased paper and different plastics are used. Interaction with the packaging material and changes of the organoleptic properties of the food may occur.
Dai et al 2011 assessed changes of taste-active compounds, including free amino acids, succinic acid and 5'-nucleotides, and other chemical components in cooked and packaged Chinese Nanjing ducks differently heated.
Heat treatment higher than 108° decreased the content of alamine and succinic acid content, and increased umami concentrations and 5'-nucleotides, free amino acids content, as well as the derived bitter and sweet taste components compared with the groups treated at lower temperatures. Dai and colleagues concluded that using lower post-production temperature after packaging may prolong product shelf life and avoid off-flavour reactions. The content of favourable umami and meat taste flavour compounds, such as 5'-nucleotides may be developed during the primary processing steps.
Umami: Umami is one of the five basic tastes together with sweet, sour, bitter, and salty. Umami is a Japanese word meaning "pleasant savoury taste".
Researchers presented a study on poisons leaching from packaging material to foods. The study detected high amounts of potential cancerogenous components of mineral oil in chocolate and other foods. [1]
This study had been requested by the Federal Ministry of Food, Agriculture and Consumer Protection.The researchers of official food laboratories of Germany and Swiss, together with the food department of the Technical University of Dresden found more than 250 compounds which can leach from cartons used as packaging material to foods like chocolate, rice, polenta, cake mix, and breakfast cereals. These poisons have their origin in mineral oil, glues, plasticisers, and other materials of paper production. Recycling paper is used to fabricate cartons and other packaging material for food and become a source of polycyclic aromatic hydrocarbons (PAH) and other poisons. The authors write that lubricants used in the production may be another source.
Later on these poisons were also found in christmas chocolade by tests of the Stiftung Warentest in chocolate figures of advent calendars sold in Germany. High contaminations were found bei products of Arko, Confiserie Heilemann and Rausch [7]. Stiftung Warentest asks for an immediate regulation forbiding the use of recycled material as food packaging without a protecting layer as described by the actual study. [8]
According to article 3 of the EG directive 1935/2004 food packaging materials for food materials and articles, under normal or foreseeable conditions of use, shall not transfer their constituents to food in quantities which could endanger human health. [9] [10]
Toxic components in recycling paper are sourced in newspapers (mineral oil, PAH), Magazines (photoinitiators, heavy metals), flyers (bis-(2-ethylhexyl)-maleate), thermopapers (bisphenol A, 2-phenylmethoxynaphthalin), glued products and cartons (plasticisers), carbon papers (Diisopropylnaphthaline). Optical brightening agents are present in all recycled papers. The authors found that reduction of these chemicals recycling procedures was insignificant.
Chemicals present in recycled cartons
Aliphatic and aromatic carbonic acid, fatty acid esters and fatty acid amides, long-chain monoalcohol, MOSH C16-C24 317 mg/kg, MOAH <C24 90 mg/kg, sum of EPA-PAK 0,3 mg/kg, DIPN 20 mg/kg, plasticiser such as Diisobutylphthalat 9 mg/kg, Dibutylphthalat 5 mg/kg, Bis(2-ethylhexylphthalat) 9 mg/kg, Diethylenglykoldibenzoat 13 mg/kg, Photoniciators such as Benzophenon 3 mg/kg, Bis(2-ethylhexylmaleat) 2 mg/kg, 2-Phenylmethoxynaphthalin 3 mg/kg, Bisphenol A 10 mg/kg, anorganic elements such as Ba 42 mg/kg, Pb 11 mg/kg, optical brightening agents total 440 mg/kg.
Highest leaching was found for mineral oil. PE- foil did not stop leaching of mineral oil, PP performed better, but is insufficient for long storage. PP foil with an acrylate layer reduce leaching of mineral oil to an almost unmeasurable amount. PET is a tight barrier with no effect of aluminium evaporation.
The mean contamination of 45 foods were for mineral oil saturated hydrocarbons (MOSH) > n-C16 = 16 mg/kg (Maximum MOSH =101 mg/kg), mineral oil aromatic hydrocarbons) MOAH = 2,8 mg/kg (Maximum 13 mg/kg). Also important contaminations were Diisobutylphthalate (mean 0,4 mg/kg, Maximum 3 mg/kg).
The Institut-Kirchhoff reported the presence of mineral oil residues up to 60mg/kg in 32% of all foods analysed between June 2010 and May 2011. All recycled cartons contained mineral oil with MOAH-fraction with a peak value of 3300 mg/kg. [11]
The study of the German and Swiss laboratories concluded that it will not be feasible to reduce te contaminants during the recycling process. This packaging must therefore be considered as a safety risk. The introduction of a barrier layer is therefore imperious. [10]
The European packaging regulation EC1935/2004 is related to materials and
articles intended to come into contact directly or indirectly with food.
According to the regulation food packaging material should under normal or
foreseeable conditions of use, not transfer their constituents to food in
quantities which could:
- Endanger human health.
- Bring about an unacceptable change in the composition of the food.
- Bring about a deterioration in the organoleptic characteristics thereof.
The regulation also describes "intelligent food contact materials and articles"
as materials and articles
which monitor the condition of packaged food or the environment surrounding the
food.
The paragraph 15 of the Packaging Regulation describes the labelling requiremets
of food packaging materials.
The Institute of Food Science and Techonology (IFST) says that nanomaterials
used in food packagings should be regulated by the Packaging Regulation. It contains a list of materials
covered by the regulation.
The war between glassworks and plastic producers fighting for increasing sales of packaging materials goes on for years. PP and PET is gaining ground because of lighter weight compared with glass and being unbreakable. These however are of minor importance when advantages of glass packagings are cited:
- Glass is inert. There is no migration of components of the plastics to the food. There is no danger of intake of plastic components and other chemicals and there are no alterations of taste caused by these substances.
- Glass is a perfect barrier to atmospheric oxygen, avoiding rancidness,
changes of colour such as brown colour of Ketchup.
Plastics can also bear poisons from herbicides, insecticides and other pesticides when the bottle was wrongly used for these substances.
Reusing bottles which had been used as described before endangers the health of the consumer because of migration of the polycyclic aromatic components.
To detect and discard these bottles a complicated system called "sniffer" is being used detecting volatile compounds of pesticides which might be present in some bottles.
This system covers only a special group of substances. It does not give an ultimative solution to avoid reusing contaminated packagings.
The Fraunhofer-Institut fr Verfahrenstechnik und Verpackung (IVV)
in Freising, Germany has developed a test of
concerning how inert PET is.
Bringing the material in contact with a sample of four classes of chemicals (alcoholes, ester, ketones, hydrocarbons and halogenated hydrocarbons) and measuring the remigration of residues in a test filling medium PET material can be examined in relation to undesired migration of chemicals in food.
As different PET plastics are produced varying from producer to producer the migration from chemicals of the packaging material itself and chemicals of poisonous fillings such as pesticides, cleaning agents,industrial chemicals and organic poisons such as aflatoxins turning the use, the reuse and even the recycling of plastics as food packaging a danger for the consumer.
PET bottles are being used increasingly for soft drinks such as cola and soft drinks, because off flavour caused by migration of plastic chemicals to food is not noticed by the consumer because of the dominance of the product flavoring.
Mineral water with carbon dioxide however shows off flavour immediately. That is why glass bottles are still used for this kind of beverage.
Unfortunately the glass bottle is being changed to PET by Gerolsteiner mineral water producer in Germany
.
The PET bottle used by Gerolsteiner has acetaldehyde residues which are below taste level. Acetaldehydes are told to be responsible for apple taste in water.
Karlsberger brewery
tries a new PET for its beer which is told to be a barrier against oxygen.
According to Walter Jungbauer from the Bund Natur und Umwelt (BUND) Bonn (Union for Nature and Environment the PET bottle for beer is a compound of PET-therephthalat and Nylon in order avoid changes of taste. This material can very hardly be recycled[12].
The argument of lower weight compared with Glass bottles is insignificant because of the difficult recycling.
Industry wants to force the one way bottles to get rid of recall of packagings.
The Coca Cola Company sells water in one-way PET bottles, filled by BEG Badische Erfrischungsgetränke being deposit free.All other soft drinks of Coca Cola are also sold in this way.
In the early times of the use of plastics as packaging material PVC was the most
common used plastic.
Multilayer-PET-bottle with EVOH barrier
EVOH barrier plastics are copolymers of ethylene and vinylalcohol
and are used as gasbarrier as food packaging in order to avoid oxygen
entering the packaging and to avoid modified atmosphere to leave the
packaging.
Normally the EVOH film is placed between two layers of PET. This method
is used for the production of bottle for beer in order to achieve same
properties of glass bottles. In 6 month storage not more then 10% loss of
CO2 and a maximum of 1 ppm of oxygen are allowed for beer glas
bottles.
This material is also used as packaging for ketchup and mayonnaise.
PVC (Polyvinylchlorid) was banned as food packages because of not entirely polymerized vinylchlorid (VC) which is carcinogenic.
PVC creates although environment problems. Being burned chloridrig acid is formed which is liberated in the atmosphere and turns out to be a part of the acid rain which is a menace to forests.
PVC is being substituted by many other polymerized products such as:
Polyethylen (PE) ,being used also as layers in other packaging materials.
Heavy density polyethylene (HDPE) which is a higher barrier to oxygen compared to PE,HDPE is used as bottles and tubs for ketchup, mayonnaise and other products with extended self life, polypropylene (PP) which is mainly used for small vessels as packaging for fine salads, margarine and dairy products and buckets such as 10 kg mayonnaise, Ketchup and other products of fast food.
Oriented polypropylene (OPP)
used as pouches,polyethylene terephthalate (PET).
Barrier resins such as ethylene vinyl alcohol (EVOH)prevent oxygen from penetrating the package, enhancing flavour, extending shelf life, avoiding rancidness.
Newcomers are metallocenes in polyolefin product which however are very expensive. The metallocene blend is based on a thee-layer coextrusion and offers strong seals at the bottom and sides of the pack with an easy-open top seal. Specially in frozen food reclosable flexible packaging is used.[1]
Flexible pouches for beverages are made of a combination of PET, aluminum and polyethylene.
Schöller ice-cream uses Tritello-Peel Pac in its 1,5 l packaging consisting of a plastic layer covered by carton. To recycle the customer is asked to separate by hand both materials and to discard them properly. Only very few people will follow these instructions.
Finish producers offer a combination of carton and three-layer
polymers (High-Barrier-Layer Esobarr). The external
carton is to suggest the packaging being entirely made of recycling carton. The
consumer believes to help environment. He does not know that that compounds of
carton and polymers are almost impossible to recycle. They are burned because a
separation of the carton and the polymer layer would be to expensive. The
arguments of the producer of the Carton-polymer packaging are a better
protection against UV rays, a barrier of gas, flavour and
humidity.
As polymers have low weight compared with other packaging materials when used
as barrier-layer they represent down to 5% of total weight. This argument
however fails to see the problems of recycling. The aim is therefore to find new
materials which can be used as barrier-layer on biopolymer basis being recycled in nature[13].
One way packagings such as glass bottles, one way PET bottles and beverage cans
made of aluminum or tinplate were in the past used only as outdoor
catering.Nowaday they gain increasingly importance.
The recycling of one way packagings and recycling of PET bottles with deposit
will soon be a task for the industry to avoid to burn the material because
of environment problems.
Recycling is possible as long as there is no mixture of plastic types.
The following products result from recycling: [14]
- The resulting product has technical properties which differ from the original product.
This is called "downcycling"
PET bottles for beverages can be downcycled to packagings for non-food
- Recycling food packagings material for the production of industrial textile fibers can be produced.
- Recycled PET material may be used as internal layer of multilayer bottles
- PET material may be used in the steel industry in high temperature ovens instead of heavy oil
- Today experiments are made to recycle PET bottles to PET recycling granulate wit identical properties of the original PET using a recondensation step. The bottles obtained with this technology can be used for food.
Significant savings in emissions are possible by changing the
way how wine is imported. The UK is the largest importer of wine in the world,
Bulk delivery is significantly more cost effective than bringing in bottled
wine.
The study says that manufacturing glass is less carbon intensive than
manufacturing PET. The lower weight of PET bottle compared with glass bottle this
impacts the transport calculation in favour to PET. Comparing carbon emission of
both, there is no gain at any side. Wrap suggests therefore the transportation of
Australian wine in bulk to archive a significant CO2 emission. Significant reductions in CO2 emissions from the transportation of wine can be achieved by converting wine from shipping in the bottle to bulk importation reducing emissions by 30% to 40%. In addition, lighter glass bottles can also achieve reductions of up to 30%.
WRAP's suggestion ist to bulk shipping and bottling in the UK into the lightest 300g bottles can result in 375g CO2 savings for every 75cl bottle of wine. Recycling and rail transportation whenever possible is being suggested for a further emission reduction.
A cost and carbon savings from adopting either or both of these options is
available at http://winebottles.wrap.org.uk
- Decree to avoid plastic waste from 12.06.1991,Packaging Decree (Verordnung über die Vermeidung von Verpackungsabfällen vom 12.6.1991 - Verpackungsverordnung.
- LMBG, Lebensmittel und Bedarfsgenständegesetz (Food and articles of daily need)
- BGV, Bundesinstitut fr gesundheitlichen Verbraucherschutz (National Institute for BgVV, embracing the Kunststoffkommission (Plastic commission)
Plastic recyclates are classified by the Plastic Commission of the BgVV in Germany as follows:
- Class 1 : Primary recyclate from rests of production.
- Class 2 : Secondary recyclate from unclean of the same type of plastic, such as returned used PET beverage bottles.
As there are no recall of one type of plastics DSD burns this class.
- Class 3 : Mixed plastic types, unclean such as the recall from the DSD (Duales System Deutschland -Dual System Germany
This class is not suited to reuse as food packaging. DSD burns all plastics recording it as thermal use
Other plastics used in nonfood articles
Common used plastics in nonfood are cited here because some of them were in headlines.
Polyurethane PUR
The typical molecular structure is ...-NH-CO-O-... This group is repeated throughout the whole long molecule.
They are known under the names of Desmopan, Vulkollan, Elastomoll, Moltopren, Porosyn.
Linear polyurethane are thermoplastics. With increasing number of links they turn out to be elastic and later hard.
They are used as soft and hard foam and many other articles. It is on market under Desmopan, Vulkollan,
Elastomoll, Moltopren, Porosyn.
Polyurethane fibres are used in textiles under trade marks like Dorlastan,
Elasthan (Germany, Lycra (USA).
Phenoplaste PF
Polycondensation of phenol or cresol with formaldehyde.
It is used in all electrical articles and as glues.
Phenoplastes are on market as Bakelite,
Dekorit, Haveg,Pertinax,
Trolitan, Trolitax.
Aminoplaste
They are obtained by polycondensation of formaldehyde with melamine.
Important types of aminoplastes are:
Melamine resin MF
Dicyandiamid resin DD
Urea resin UF
Polyester
The typical molecular structure is ...-CO-O-... (ester group). This group is
repeated throughout the whole long molecule.
It is being obtained by polycondensation of high alcohols and carboxylic acid.
Using maleic acid or fumaric acid unsaturated polyester resines
UP are formed. They are known as
Trevira, Diolen (Germany), Dacron (USA).
Epoxy resines EP
Reaction of polyaddition and polycondensation between epoxy (such as
Epichloridrine) and a diphenol (such as diphenyl propane) originating an
intermediate product which hardens together with phthalic acid anhydride or
diethylentriamine as hardening agent
Polymethylmethacrylate PMMA
. It
is the product of the polymerization of methacryl acid methylester
It is known as "organic glas" as security glas under the name of
Plexiglas and Resartglas.
Polytetrafluorethylene PTFE
Product of polymerization of tetrafluorethene.
It is stable up to 260°, stable against ozone. It is used as gaskets.
Polyvinylacetate PVAC
It is a product of polymerization of vinylacetate and is used in solution as paint. Cellulose acetate CA:
Esterification of cellulose with acetic acid anhydride in presence of sulphuric
acid.
Celluloid CN:
It is cellulose dinitrate with camphor as plasticiser.
It is on market under Perlon(Germany) and Nylon(USA).
It is a product of polymerization of acrylnitril. Dralon, Dolan (Germany) Orlon (USA)
On regard to vanishing natural resources it is important to reduce the quantity of plastics as packaging material.
Industry should look to the example of German mineral water producers: They all use the same standard bottle. This could also be done with all kind of food. The glass could have the sizes of 125 , 200 ,250,400 500 and 750 ml. For the size of 100 to 250 ml a 53 twist-off closure and 63 closure for 400 to 750 ml
glass should be used.
The refund system should be used and the glasses could be cleaned in central washing factories sterilize and protecting the pallets with shrinkable foil. Food producers could order glasses from the washing factory instead from the glassworks.
The Heinz Ketchup would be found in the same bottle as Kraft Ketchup, the Thomy mayonnaise together with Hellmann mayonnaise and all fine food together with herring, mustard, coffee creamer and marmelade.
A universal glass for all products and brands is a nightmare for a marketing manager but at the same time it is a blessing for the future of his son.
Label and closure gives sufficient ground for the work of art designer to create an individual touch for every product and every brand.
Unfortunately there is a move from glass to plastic as noted by increasing number of packaging of soft drinks and soft drinks as well as traditional products such as Nestlé Coffee Mate, the coffee creamer of UK changing from glass to PET (polyethylene terephthalate) jars with a shrink-sleeve label[16].
Reuse of bottles:
Glass bottles are reused about 45 times. PET bottles are reused about 15 times.
As plastics fail to be recycled it is being burned. Precious materials are so lost. We should try to change to glass packaging.
Recycling of glass in the way which is practiced at the moment loses fossile or atom energy to melt and form glass packaging. The refund and cleaning system of a standard glass packaging would reduce
energy needed to reuse glass and jars.
As recycling organizations such as The Green Dot in Germany and Spain fail to reach proper amount of recycling of plastics, government should regulate the Euro glass. This way is better as dissolving the recycling organizations leaving the responsibility in the hand of every producer to recall his own packagings.
Increasing problems with environment and vanishing resources will soon force the producers to think over their marketing strategy. The situation will also force the consumer to accept reduction of amenities which can no longer be maintained.
Industry tries to change from glass to plastics because of reduced costs in handling, weight transport costs and costs of cleaning, disinfection for
a reuse. Due to regulations concerning recycling of packagings in Germany there is a minimum share of 72% defined. This limit was not achieved in 1998.
It is sure that for 1999 the limit will not be achieved.
According to the regulation there will be a compulsory deposit starting from the year 2000 of 0,50 Dm for beverage packagings from 0,2 liter up to under 1,5 liter and greater packagings starting with 1,5 liter 1,00 Dm.
European regulations concerning packaging recycling
European guideline 94/62/EG from December 1994 regulates the recycling of packagings in the European Community.
According this guideline the government of the Community may regulate recycling of
packaging materials in order to promote reuse of bottles but they are not allowed to create trade hindrances. Not recyclable packagings are therefore protected by this regulation.
The guideline also defines a rate of 50 to 60% of use of packaging material in any form whatsoever including heat recycling and 25 to 45% recycling the material getting new products.
These scores are ridiculous low and shows that the governments should force the introduction of standard packagings like the Euro glass.
The type of Packaging can interfere in the growth of bacteria[17].
Aerobic bacteria can grow. Fresh meat packed in cellulose film so
as used in tray packaging is threatened by
Pseudomonads like Pseudomonas fluorescens and Pseudomonas fragi as dominant bacteria producing smell
and slime.
The atmosphere in the packaging can be modified according to the food which is being packed.
Enzymes, temperature and competitive growth can produce gas like CO2.
For some food gas packaging with modified atmosphere are used.
Vacuum inhibits the growth of aerobic microbes such as Pseudomonas,Bacillus, moulds. In these packagings the growth of lactobacillus is dominant. Enterobacteriaceae can grow under anaerobic conditions.
Nitrogen, CO2 and in some cases O2 are used.
Nitrogen has no activity against bacteria. It increases shelf life substuting oxygen.
CO2 acts bacteriostatic on gram negative aerobic bacteria and bactericide
because of its undissociated part of H2CO3 which enables CO2 to trespass the cell membrane and act bactericide on the cells of the bacteria.
Lactobacillus is not affected by CO2.
CO2 can reduce growth of Listeria on meat.
| Polymer |
used as |
Filling product |
|---|
| PVdC,EVOH,Acrylnitril |
Oxygen barrier |
|
| PET/PVdc-PVC/PE |
multilayer foil |
red meat |
| HDPE, PVdC,PP |
water vapor barrier |
|
| PA/PE-PVC/PE |
multilayer foil |
treated meat |
| HDPE,PP |
stability,suitable |
|
| |
for microwave oven |
|
| |
|
|
| PET/PVdC/PE |
multilayer foil |
poultry |
| Nylon |
high temperatures |
|
| |
resistant |
|
| |
|
|
| PET/PE/PVdC-PVC/PE |
multilayer foil |
fresh fish |
| CPET |
mechanical resistance, |
|
| |
high temperatures |
|
| |
resistant, oxygen barrier |
|
| |
|
|
| PET/PVdC/PE |
multilayer foil |
Pizza |
| APET |
mechanical resistance, |
|
| |
oxygen barrier |
|
| |
|
|
| PET/PE/PCdC |
multilayer foil |
Cheese |
| Polyester |
high temperatures |
|
| |
resistant, flexibility |
|
| |
and resistant to perforation |
|
| |
|
|
| Metallized PET/PE-metallized PA/PE |
multilayer foil |
dried products,coffee |
| PVC/PET |
mechanical stability, |
|
| |
some types |
|
| Micropore foil-LDPE/OPP/PVCPA/PE |
multilayer foil |
fresh vegetables |
| |
|
|
| LDPE, HDPE, EVA |
sealing layer |
|
| EVA |
highly permeable to |
|
| |
oxygen and CO2 |
|
| Abbreviation |
material |
|---|
| ABS |
Acrylbitril-Butadien-Styrol Copolymer |
| APET |
amorphous polyester |
| CPET |
crystalline polyethylenterephthalat |
| ECTFE |
Ethylen-Chlortriefluorethylen Copolymer |
| ETFE |
Ethylen-Tetrafluorethylen-copolymer |
| EVA |
ethylen-vinylacetat |
| EVOH |
ethylenvinylalcohol |
| FEP |
Tetrafluorethylen-Hexafluorpropylen |
| HDPE |
highdensity polyethylen |
| LDPE |
lowdensity polyethylen |
| OPP |
streched polypropylen |
| PA |
Polyamid (Nylon) |
| PC |
Polycarbonat |
| PET |
Polyethylenterephthalat |
| PE |
Polyethylen |
| l
PFA |
Perfluor-Alkoxylalkan |
| PMMA |
Polymethyl-Methacrylat |
| PMP |
Polymethylpentene |
| PS |
Polystyrol |
| POM |
Polyoxymethylen |
| PP |
Polypropylen |
| PPO |
modified polyphenylenoxid |
| PTFE |
Poly-Tetrafluor-Ethylen |
| PVC |
Polyvinylchlorid |
| PVdC |
polyvinilidencloride |
| SAN |
Styrol-Acrylnitril-Copolymer |
Multilayer foils may have PE, PVdC and PET as typical components.
Saint-Eve and colleagues 2008 studied the influence of packaging polymers
(polypropylene or polystyrene) and glass on yogurts with 0% or 4%-fat
content during the 28 days of storage at 4 °. The authors found that
0%-fat yogurt conditioned in glass displayed the lowest aroma quantity
decrease of the three types of packagings. Polystyrene packaging was found to
be preferable before polypropylene in limiting aroma compound losses and for
avoiding odour and aroma defects. The 4%-fat yogurts were less affected by
the packagings.
- Plastic bags are bad because they may contain PVC which develops toxic gases as it is burned. Use paper bags.
- Aluminum cans are hostile to environment because they can hardly be recycled.
- Greaseproof paper is better as plastic foodwrap because the later may contain harmful softener
Nonylphenol is an industrial chemical which interacts with human hormones and
produces cancer. Its synonyms are p-nonylphenol,4-nonylphenol,
C15H24O. Nonyphenoles were found in mineral waters due to migration
from the plastic seal of the caps of bottles.
Another source of nonylphenol in food arethe nonylphenolethoxylate which are
used in the production of plastics for wrappings and packagings of food.
Nonylphenolethoxylate act as emulsifier and stabilizer in plasticizers for
Packagings. Nonyphenoles are breakdown products of norylphenolethoxylate
detergents usedin household and industrial
cleaning products.which contaminate food. Their contact with foods leads to
the contamination with nonyphenoles.
Very high amount of nonylphenoles were found in apples and in tomatoes by the
Research Center in Julich.
The estimated human intake of nonylphenoles is 7.5 microgram a day. The
content of nonylphenole in pesticides are now being analyzed.
Baby milk in Tetrapack was found in October 2005 as being contaminated with
traces of Isopropilthioxantone. This chemical is being used for carton
printing leaking from the carton to any fatty products like milk when it is
exposed to sunlight's ultraviolet rays. Researches indicate that the migration
of ITX has no known health
effects. According to Tetra Pax ITX is not prohibited for use in food
packaging by the EU. However EU packaging rules, as amended in 2003, require
that food contact materials do not migrate into products meant for human
consumption.
EU regulations
- Commission Directive 2002/72/EC of 6 August 2002 relating to plastic
materials and articles intended to come into contact with foodstuffs.
http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2002:220:0018:0058:EN:PDF
- Corrigendum to Commission Directive 2002/72/EC of 6 August 2002 relating
to plastic materials and articles intended to come into contact with foodstuffs
(OJ L 220 of 15.8.2002)
http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32002L0072R(01):EN:HTML
- Regulation (EC) No 1935/2004 of the European Parliament and of the Council
of 27 October 2004 on materials and articles intended to come into contact with
food and repealing Directives 80/590/EEC and 89/109/EEC http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2004:338:0004:0017:EN:PDF
- Commission Directive 2004/19/EC of 1 March 2004 amending Directive
2002/72/EC relating to plastic materials and articles intended to come into contact with
foodstuffs
http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2004:071:0008:0021:EN:PDF
ITX is being used as curing process during ultraviolet printing processes when
using UV inks. This process is also being used for packaging for water,
juices, ice teas. No migration was occurring for most of those beverages,
except in the case of some citrus juices such as orange and lemon, and milk.
Clear juices such apple, grape and cranberry do not seem to be affected.
The European Food Safety Authority (EFSA) will undertake a risk assessment of
the chemical. Health concerns about packaging chemicals, such as phthalates,
have raised consumer awareness of about the risks posed by materials that may
come into contact with food.
According to the German BfR the occurrence of a chemical in a food does not in
itself constitute a risk to health. It is the harmfulness of the substance and
the degree to which the consumer comes into contact with the substance that
determines the scale of possible damage and the probability that it will
occur. Residues of printing inksin foods may, therefore, be safe but they may
equally constitute a serious risk to health.
Talks between the Plastics Committee and representatives of the printing ink
industry at BfR revealed that no technology is currently available to prevent
the migration of substances from printing inks to food through a set-off
effect or because of penetration of the packaging material. Nor is this
situation likely to change in the short term.
Given the lack of data, a health assessment is frequently not possible at the
present time. As the manufacturers bear responsibility for the safety of their
products, they should do everything in their power to prevent the migration of
substances of this kind to foods and put together the data needed for a health
assessment.
The printing inks may contain the photo initiator isopropyl thioxanthone
(ITX). Public agencies in Italy and Germany have detected residues of ITX in
foods from cartons. Cartons for beverages like milk, cocoa or juice are often
printed in different colours and have benn found to contain the ITX compound.
Also olive oil has been found to be contaminated with ITX.
ITX is contained in UV-hardening printing inks. The cardboard used to make the
packaging may be transported on rollers to the food filling plant and then
moulded on site into the corresponding packaging. Constituents of the printing
inks applied to the outer packaging material can, by means of spread
(set-off), reach the inside that comes into contact with food.
Furthermore, there may be migration through the packaging material in the case
of pre-moulded packaging unless effective barrier layers, e.g. aluminium
foils, have been applied. BfR has examined the available toxicological data
for the chemical isopropyl thioxanthone (ITX).
In line with the assessment scheme of the European Food Safety Authority and
customary assessment practice at BfR and regarding substances used in the
production of food commodities, the available data on the exclusion of
genotoxicity are only sufficient to evaluate substances with a maximum
migration level of 50 microgram/kg food. As, however, the ITX measurements in
Germany revealed far higher levels, additional data would be needed for
toxicological assessment. BfR does not have the necessary data on toxic
effects, bioavailability or toxicokinetics of the substance.
A larger manufacturer of beverage cartons has informed BfR that it switched to
a new printing method for infant and baby food on 30 September 2005. It no
longer uses any UVhardening printing inks in order to prevent migration of ITX
from the package to the food for milk and fatty products.
The phenomenon of the migration of constituents from printing inks used on the
outer packaging to foods as a consequence of both penetration of the packaging
material and set-off to the inner packaging is a fundamental issue. Set-off
cannot, in principle, be ruled out for any packaging material processed on
rollers or in stacks. Besides the data on ITX, BfR is also aware of migration
findings from packaging to food for other photo initiators used in printing inks
like 2-ethylhexyl-4-dimethyl aminobenzoate and
4,4'-bis(diethylamino)-benzophenone and 4,4'-bis(dimethylamino)-benzophenone. BfR
is, therefore, of the opinion that there is an urgent need to lay down
requirements for the use of printing inks for food commodities on the European
level.
Benzophenone and 4-methylbenzophenone
are chemicals used in printing inks for food packaging. They are used as
initiators for printing inks cured by UV radiation. Due to their volatility
they can migrate through the packaging to the food if there is no functional
barrier.
In February 2009 certain breakfast cereals were found to be contaminated with
4-methylbenzophenone. EFSA's expert Panel on food contact materials considers
there is no health risks from the short-term consumption of breakfast cereals
contaminated with 4-methylbenzophenone. However, for children, based on the
highly conservative scenario (high consumption of breakfast cereals, highest
concentration of 4-methylbenzophenone), a health concern could not be
excluded. Should the use of the substance go on a full risk assessment will be
necessary.
The Panel considered the safety threshold for benzophenone which was used as
the basis of EFSA's urgent advice to the Commission in March to be very
cautious, as it was based upon adaptive (i.e. reversible) changes reported in
experimental animals as a result of their exposure to benzophenone rather than
adverse effects as such.
The Panel rose the 1992 benzophenone TDI of 0.01mg/kg bw to 0.03mg per
kilogram of bodyweight. The TDI of benzophenone should not be applied to
4-methylbenzophenone and hydroxybenzophenone.
According to the Federal Institute for Risk Assessment (BfR) concentrations of
up to 5 milligram per kilogram of the chemical di-isobutylphthalate (DiBP)
have been found in food such as fat-containing, powder and fine grain foods
like rice, baking mixtures or breadcrumbs packaged in cartons.
In animal experiments DiBP was found to be reprotoxic and embryotoxic. It is
used as a plasticiser in dispersion glues for paper and packaging and when
they are recycled DiBP can be found in paper and board packaging. The BfR and
the Federal Environmental Agency (UBA) advocates a voluntary undertaking by
the manufacturers and processors of paper and board to no longer use
DiBP-containing glues or printing inks to reduce the DiBP content in recycled paper.
The data from long-term toxicity studies are not available therefore BfR
recommends a specific restriction on the migration of DiBP to foods, a
so-called specific migration guidance value, of 1 milligram DiBP per kilogram
food. For baby and infant formula this value should be 0.5 milligram. This
was based on the Health assessment made by the European Food Safety
Authority (EFSA) on di-n-butylphthalate (DnBP) which has a similar structure
and effect.
DiBP is being proposed to be classified as reprotoxic substance and to be
included in Annex I of the Dangerous Substances Directive 67/548/EEC)
[24]
Phthalates in medical devices
[25]
Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer used in medical products
made with polyvinyl chloride (PVC) plastic and may be toxic to humans. DEHP is
lipophilic and binds noncovalently to PVC, allowing it to leach from these
products. Medical devices containing DEHP are used extensively in neonatal
intensive care units.
Previous research has shown that newborns treated at neonatal intensive care
units may receive doses of DEHP at 2-3 times the average daily adult exposure.
Studies have linked di(2-ethylhexyl) phthalate (DEHP) with reproductive and
developmental toxicity, and have demonstrated an especially pronounced effect
on testicular development when administered postnatally.
The study classified low-DEHP exposure group including infants receiving
primarily bottle and/or gavage feedings; the medium exposure group included
infants receiving enteral feedings, intravenous hyperalimentation, and/or
nasal continuous positive airway pressure; and the high exposure group
included infants receiving umbilical vessel catheterization, endotracheal
intubation, intravenous hyperalimentation, and indwelling gavage tube.
Ronald Green and colleagues conclude that intensive use of DEHP-containing
medical devices in intensive care units results in higher exposure to DEHP as
reflected by elevated urinary levels of MEHP in these infants. The use of
phthalates should be reduced, if possible completely eliminated from products
which come in contact with food, as well as in medical devices or other
applications which come in contact with humans.
[26]
| Product |
Modified atmosphere |
Remarks |
|---|
| Red meat |
80% O2 + 20% CO2 |
CO2 reduces growth of Pseudomonas |
| |
|
aerobic bacteria which often |
| |
|
spoils red meat.High concentration |
| |
|
of oxygen is needed to keep red colour. |
| |
|
|
| Porc |
60% O2 + 40% CO2 |
CO2 reduces growth of aerobic bacteria |
| |
|
less O2 is needed because of reduced red |
| |
|
colour of porc compared with beef |
| |
|
|
| Poultry |
50 - 80%CO2 + 20 - 50% N2 |
A high headspace with gas is important |
| |
|
|
| Sausages |
20% CO2 + 80% N2 |
|
| |
|
|
| Sliced heated meat |
20% CO2 + 80% N2 |
|
| |
|
|
| Fish, high-fat |
60 - 70% CO2 + 30 - 40% N2 |
No oxygen should be used |
| |
|
to reduce rancidity |
| |
|
|
| Fish, low-fat |
30 - 40% O2 + 30 - 70% CO2 |
Oxygen is used to keep red |
| |
+ 0 - 40% N2 |
colour of low-fat fish and seafood |
| |
|
It also reduces growth of anaerobic |
| |
|
bacteria such as Clostridium |
| |
|
and its toxins |
| |
|
in case of long shelf life |
| |
|
|
| Sliced fish,cooked |
20% CO2 + 80% N2 |
|
| Hard Cheese |
80 - 100% CO2 + 0 - 20% N2 |
|
| Sliced hard cheese |
80 - 90% CO2 + 10 - 20% N2 |
|
| Soft cheese |
20 - 40% CO2 + 60 - 80% N2 |
|
| |
|
|
| Gateau |
50 - 70% CO2 + 30 - 50% N2 |
Storage at +4 - +7°C |
| Cake and bread |
20 - 40% CO2 + 60 - 80% N2 |
|
| |
|
|
| Pizza |
30 - 60% CO2 + 40 - 70% N2 |
|
| Pommes frites |
70 - 80% CO2 + 20 - 30% N2 |
|
| Salads with dressings |
100% N2 |
|
Spoilage of food can be caused by:
- The nature of bacteria and their amount.
Bacteria can be aerobic, growing in presence of oxygen such as Pseudomonas, Acinetobacter and moraxella.Or they are anaerobic,
growing in absence of oxygen such as Clostridium producing toxins and Lactobacillus producing lactic acid.
- Water activity aw
- pH
- Cell breathing
- Composition of the food
- Storage temperature.
Low temperatures reduces bacteria growth.
Some bacteria grow even under low temperatures, the psycrophilic like Pseudomonas
- Hygiene during production
Bacteria can be present in the raw material,additives and environment, such as our skin,used utensils and air.
- Gasatmosphere
oxygen can cause rancidity, oxidizes vitamins, Nitrogen can replace oxygen.
Oxygen is sometimes necessary to keep the red colour of fresh meat.
The choice of the gas to be used during filling is therefore very important and varies from one food to another.
- Good Manufacturing Practice
CO2 reacts with water forming carbonic acid which increases acidity of the product reducing bacteria growth.Nitrogen can replace CO2
In Products such as cottage cheeseand dairy cream CA packaging with nitrogen instead of oxygen is being used.
Hard cheese is packed under up to 100% CO2 to reduce bacterial activity and stabilizes consistency of the product.
Soft cheese is packed under 20 - 40% CO2 because otherwise the packaging would
shrink because the gas gets in solution with the product.In this case 30% of of CO2 should not be exceeded.
[27]
Different attempts have been undertaken to slow down oxidation and its effects on rancidity and browning of meat like the use of rosemary extract as ingredient, or adding the extract to the polypropylene film used to package freshly cut meat, and the use of carbon monoxide modified atmosphere packaging.
Factors which influence the colour of meat are temperature, relative
humidity, oxygen partial pressure, light, and lipid oxidation. Such natural extracts allows meat packagers to
use high-oxygen atmospheres in sealed packages to maintain freshness without
having to worry about browning. Meat and meat
products kept under low-oxygen atmospheres with carbon monoxide look fresh for
much longer time than any other artefact. The gas reacts with the meat pigment
myoglobin to create carboxymyoglobin which has a pink colour.
FDA had allowed carbon monoxide use as generally recognized as safe (GRAS) in meat und tuna
packagings to keep it looking fresh. The GRAS regulatory category allows producers to use an additive or a procedure without public review or formal agency approval.
A petition, filed by Kalsec(R), Inc. of Kalamazoo, Michigan, in 2005, urged the FDA to withdraw its July 2004 decision and related decisions to allow the presence of carbon monoxide in meat packaging. http://www.co-meat.com/release.html and http://www.fda.gov/ohrms/dockets/dockets/05p0459/05p-0459-cp00001-toc.htm
Consumer groups such as leaded by Donna Rosenbaum of Safe Tables Our Priority, an advocacy group in Burlington, and the Consumer Federation of America wrote to the FDA in support of a ban. The groups argue that carbon monoxide may mask visual evidence of spoilage resulted from storage temperature variations. They challenge the Food and Drug Administration for allowing the practice without a formal evaluation of its impact on consumer safety.
As an alternative to a ban, consumer call for carbon-monoxide-treated meat labelling so they can decide on what they are buying.
Industry representatives say that the use of carbon monoxide is safe because other signs like odour, slime formation and a bulging package are indicators of spoilage.
The consumer groups allegate that FDA regulations under the Food, Drug and
Cosmetic Act (FDCA) expressly prohibit the use of carbon monoxide in "fresh
meat products", the FDA did not have legal authority to permit the use of
carbon monoxide because it is an unapproved and prohibited color additive.
Regulations of the U.S. Department of Agriculture's Food Safety and Inspection
Service (FSIS) prohibit the introduction of ingredients in fresh meat that
function to conceal damage or inferiority, or give the appearance the product
is of better or greater value.[28]
European Union ban of carbon monoxide as colour
stabilizer
The European Union has banned the
use of carbon monoxide as a colour stabilizer in meat and fish. A December
2001 report from the European Commission's Scientific Committee on Food
concluded that the presence of CO may mask visual evidence of spoilage should
the meat become inadvertently warmer at some point
Modified atmosphere packaging (MAP) gases are classed as food additives under
two Acts, the Directive of food additives (89/107/EEC) and the Directive of
the use of food additives other than colours or sweeteners (95/2/EC). In June
2003, The European Parliament Environment Committee voted to outlaw carbon
monoxide as a food additive, and thus as a MAP gas, because it could mislead
the consumer as to the freshness of the meat by maintaining the red colour of
the product
Japan, Canada and Singapore also ban the use of carbon monoxide in tuna.
The Federal Institute for Risk Assessment (BfR) assessed packaged meat on
supermarket shelves carrying the wording "Packaged in a controlled
atmosphere". This means that a gas mixture with, in some cases, a high oxygen
level has been added to the packaging. The meat retains its red colour for far
longer but matures more quickly and the fat oxidises and becomes rancid faster
than in the case of other fresh meat.
Cholesterol is present in numerous foods of animal origin. When exposed to
oxygen it oxidises and cholesterol oxidation products (COPs) "Oxysteroles"are
formed. It was observed that the storing of previously heated meat leads to a
major increase in certain COPs. Studies indicate that cholesterol oxidation is
accelerated in the presence of an elevated oxygen concentration, as is the
case in the described controlled atmosphere packaging.
More cholesterol oxidation products (COPs) seemingly form in the
oxygen-enriched atmosphere. Consumers ingest these COPs from all
cholesterol-containing foods. Their impact on the human organism has not been
fully elucidated. The additional amount of COPs ingested by consumers from
oxygen-enriched packaging is very low and the BfR does not expect any health
risk from the additional amounts of cholesterol oxidation products.
The BfR concluded that the COP intake by consumers from fresh meat packaged
in a controlled atmosphere is only marginally higher. New findings on
oxysterols, however, puts the conclusion of the German BrF under new
discussion.
The BfR stresses that the term "Packaged in a controlled atmosphere" does not say
anything about the microbiological quality of the meat, i.e. the germs it may be
contaminated with. When preparing fresh meat from this kind of packaging,
consumers should observe the same kitchen hygiene rules as they do for other
meat. Professor Andrew Mills develops an intelligent plastic indicator which can be incorporated in food packaging material. It becomes coloured when the food packaging is broken, damaged, or the food has been poorly refrigerated. Professor Mills wants to use the "freshness indicator" combined with modified atmosphere packaging to prolong shelf life. The new plastic aims to replace costly labels which are currently used to indicate leakage of the gases of the modified atmosphere.
Professor Mills hopes to increase food safety and to reduce unnecessary waste of food after "sell-by"dates have expired.
The new intelligent packaging is intended to protect consumer against spoilage resulting from leaky packaging or unsafe storage temperatures. However, it will not become a device to extend shelf life beyond the " best before" dates and "sell-by" dates. These dates are set by the producer and are already kept as high as possible. Ageing of food means decay of vitamins, antioxidants and other active elements. Some food poisoning agents do not produce metabolites which trigger the indicator of packaging, and the indicator cannot react to all metabolites of all bacteria and viruses known by the food industry. The chemistry of the indicator which is being developed by professor Mills is not made public, and ultimate evaluation of its function is therefore not possible.
The "freshness indicator" of professor Mills may be welcome as an additional safety packaging item, but it is not a silver bullet. The importance of "sell-by" date should not be diminished, and the consumer should keep looking at these dates for safety, microelements and quality of food.
Retailers have to improve its warehousing to reduce the amount of foods being discarded because of expiring dates using modern logistic tools. Keeping the right amount of ware at the shelves is the the best way to keep fish and meat fresh on sale and reduce waste.
Macrophages play important role in immunity, but may also increase the risk
of atherosclerosis are active in inflammations. Oxysterols were found to
influence the activities of these macrophages. Shibata and Glass 2010 explain
that oxysterols also regulate lipid metabolism, immune function, and
cytotoxicity mediated by specific oxysterol sensors, including liver X
receptors, Insigs, and members of the oxysterol binding protein and related
proteins.
Several studies found cholesterol metabolism may cause Alzheimer's disease and age-related macular degeneration. Dasari and colleagues 2010 report that
the cholesterol oxidation metabolite 27-hydroxycholesterol (27-OHC) caused
several negative effects such as beta-amyloid peptide accumulation and
oxidative cell damage. The authors suggest that this oxysterol is a common
pathogenic factor for both Alzheimer's disease and age-related macular
degeneration. [32]
Oxysterols are known to be active in age-related macular degeneration, a major
cause of blindness. Dugas and colleagues 2010 found that oxysterols
(7beta-hydroxycholesterol (7beta-OH), 7-ketocholesterol (7KC),
25-hydroxycholesterol (25-OH)) have cytotoxic, oxidative, inflammatory, and/or
angiogenic activities in human retinal cells. Reservatrol from red wine may be
used to treat age-related macular degeneration because of its protective effects
against oxysterol-induced cell death and the segregation of a protein molecule
called vascular endothelial growth factor. [33] Perez and colleagues 20120 report that feed
supplemented with vitamin E and sodium selenite/ selenomethionine reduced lipid oxidation in frozen-raw and cooked omega-3 enriched dark chicken meat.
Linseed product was used to enhance the alpha-linolenic acid source in feed.
Oxysterols remained stable in frozen-raw meat stored for 6 month with both
antioxidants. During cooking vitamin E reduced oxysterol formation, but selenium
compounds did not. During roasting selenium compounds increased oxysterols. After
12 month at -30° no protection was found.
Following recent studies all efforts should be undertaken to avoid additional
formation of oxidised Cholesterol, known as oxysterols in meat. Meat packaged in
a controlled atmosphere should not allowed to be marketed. High levels of oxygen
are used to keep the red colour of the meat for a log time and simulate fresh
product. Rising number of bacteria and other spoiling of minced meat or other
products are not avoided and cannot be noted by the consumer looking at the
colour of the meat. Harmful oxysterols are created with the sole purpose to
extend the optical shelf life of the meat. There is a growing demand for minimal
processed foods without synthetic chemical preservatives. Preservation methods
are being developed using high pressure systems, asseptic filling, ohmic
heating, pulsed electric field, irradiation and bright light technologies. [35]
Plastics are made from ethylene, propylene, styrol, polyester such as
polycaprolacton, Polyesteramide and polyesteruretane aall coming from petroleum.
Widely used plastics are:
- Polyethylene PE
- Polystyrol PS
- Polypropylene PP
- Polyvinyl chlorid PCV
In 10 years the world demand for plastics doubled, summing 224 million tons in the year 2004.
Europe consumed one fourth of the world output, whereas Germany accounted for
17,5 million tons/year, which is 8% of the world production, more than half
of it, 9 million tons, were used as packaging.
In an effort to counter further growth of petrol packaging, bioplastics are
being developed using renewable raw materials like starch, cellulose, sugar
gelatine, chitin, polyhydroxicarbon acid ester and polyamin acid won by
biotechnology technology. Their price is, however, up to four times higher as
petrol originated plastics. The world production of bioplastics in 2004 summed
only 250.000 tons
Other raw materials which are used to form bioplastics are
Some bioplastic articles are foamed duroplastic from starch as trays for
vegetables and other foods and bottles from PLA for mineral water.
Different projects are running to improve water resistance of starch and starch plasticizers for the preparation of thermoplastic starch (TPS) for use in structural packaging materials for consumer products. Despite all efforts, application of TPS is still limited by its low mechanical and water resistance. Corn starch and cassava bagasse which is a by-product from cassava starch production are renewable sources for thermoplastics. [37]
Synthetic biodegradable polyesters fall into two broad categories. One is highly amorphous, imparting flexibility and clarity comparable to a conventional LDPE copolymer. A second group of semicrystalline polyesters is more rigid, with properties similar to PET, PP, or PS. [38]
Starch is an abundant, inexpensive, renewable, and fully biodegradable natural raw material. However, the hydrophilic character of starch leads to poor adhesion with the hydrophobic polymer in starch-polymer blends. In spite of its relative weakness and a about 60° melting point that is too low for many applications, polycaprolactone (PCL) has recently received much attention due to its flexibility and biodegradability. Additionally, similar to other aliphatic polyesters, such as polylactide (PLA) , polyglycolide (PGA), PCL and their copolymers. PCL is, however, more expensive. Hence a blend of PCL with the cheaper material starch, with a reactive functional group grafted onto PCL to improve adhesion and dispersion of the two immiscible phases, would appear to offer the best of both worlds.
Blends of regenerated cellulose and polyeteruretane are also being developed. Cellulose is built of polymerised glucose units. Thermoplasticity and biologic degradation are related to degree of derivatization (the number of hydroxil groups OH of each glucose unit which have been substituted) Every glucose unit has three OH group The average substitution degree AS value [German DS ) can vary from 0 to 3.
Derivates with AS 2.5 up to 3.0 are thermoplastic and can be extruded with available equipment. However only derivates with AS number below 1.5 are biodegradable.
To overcome this problem derivates with low AS numbers and long side chain with
low AS number are being tested, such as cellulosepolyhydroxihexan acid ester. [39]
Polylactic acid (PLA) may become an alternative to PET, HIPS, PVC, and cellulosics in some high-clarity packaging roles. It is synthesized from processed hybrid corn rich in amylose. Cargill has signed a joint venture partnership with Japan-based Teijin Limited to manufacture and market polylactic acid (PLA) under NatureWorks in 2007.
Recently an acrylic acid grafted polycaprolactone and starch composite (PCL-g-AA/starch)
was considered to present best results for packaging material. [40][41]
Improved functionality of bioplastics and their growing market lead to more
interest. Moreover, the risks created by imports and increasing costs for
fossil raw materials play as much a role as climate change, whose negative
effects are becoming increasingly pronounced. In consequence the plastics
industry is putting more and more emphasis on the use of renewable raw
materials. [42]
Corn-based biodegradable plastics could be used as an alternative to
petroleum-based plastics. Catsup or fruit juice and other products are filled
in the container while still hot from pasteurisation. Current corn based
plastic containers cannot withstand hot filling at about 72°. According
to chemist William J. Orts of the U.S. Department of Agriculture (USDA) and a
team of Lapol, of Santa Barbara, Calif., develop a corn-derived plastics
which is more heat-tolerant than current ones.
Orts and colleagues 2010 explain that corn-based plastics are made by
fermenting corn sugar to produce lactic acid. The lactic acid is used to form
polylactic acid, or PLA. A heat-deflection temperature modifier that is blend
with PLA will turn it more heat-tolerant. The modifier is more than 90 percent
corn-based and is fully biodegradable.
Gregory M. Glenn and Simon K. Hodson in 2009 developed at the ARS Western
Regional Research Center in Albany, Calif., a biofoam made from starch from
potatoes, wheat or corn, instead of from petroleum. Rigid, custom-fit foam pieces
protect products inside cardboard boxes during shipping. Large amount of
polysterene from petroleum are used as packaging material and is discarded as
waste. Biofoams may become an alternative to oil.
Developing bio plastics which are degradable and present similar proprieties as
oil derived packagings may reduce the dependence on crude oil. Food packagings
are an important part of communal waste and pollute the ocean.
The packaging material, called Calymer from Ecolean, consists of 40% calcium carbonate and polymers, which simply act as the binding agent. This
material is flexible and tough with exceptional environmental properties.
Incineration transforms the binding agent of packaging waste the into water
vapour and carbon dioxide and the calcium carbonate is returned to nature.
Polylactic acid (PLA), a material made from corn that can be used for food
packaging under the brand Biophan.
The switch to biodegradable packaging is being driven by
environmentally-conscious consumers the price of oil and recycling regulations.
Polylactic acid can be transformed within 45 days in CO2 in a composting
plant. The German Packaging Ordinance, giving preferential treatment up to
2012 to biologically degradable packaging supports this packaging material.
Innovations on the field of biodegradable
plastics
Amcor, together with
Plantic Technologies develop a biodegradable, flexible plastic packaging for
confectionery.
NatureWorks, a Cargill daughter released a polymer of corn starch, the polylactic acid (PLA) .
Danisco has produced a biodegradable plasticiser from hardened castor oil and
acetic acid.
Stanelco markets a natural, biodegradable food packaging based on starch,
called Starpol 2000.
BASF will launch Ecovio plastic, a biodegradable plastic made up of 45 per
cent PLA from NatureWorks together with biodegradable plastic Ecoflex, which
is derived from petrochemicals.
Companies which have been using PLA plastics as packaging for foods like
organic milk in US is Naturally Iowa. Retailers like Delhaize in Belgium and
Auchan in France have also been testing PLA for various food packaging.
Films forming solutions composed of Amaranth (Amaranthus cruentus) flour (4.0
g/100 mL), stearic acid (5-15 g/100 g of flour), and glycerol (25-35 g/100 g
of flour) were prepared by an emulsification process. The films produced under
these conditions exhibited superior mechanical properties (2.5 N puncture
force, 2.6 MPa tensile strength, and 148% elongation at break) in comparison
to those of other protein and polysaccharide composite films,
[47]
Low density polyethylene (LDPE) film widely used in agriculture for mulching
crops could become substituted by degradable plastics which do not need to be
removed from field at the end of the season.
Plastics derived from petrochemicals degrade very slowly. Degradables plastics
degraded rapidly by photodegradation and/or biodegradation.
Degradable plastics made from starch-based polymers are:
The breakdown of photodegradable plastics depends on irregularities in the polymers and photosensitive substances, called promoters, such as carbonyl groups and metal complexes, Their chemical composition varies:
- Carbonyl Group: Ketone Carbonyl Copolymers
A carbonyl group, vinyl ketone comonomer, is added to the polymers of plastics such as polyethylene (PE) and polystyrene (PS). the finaldegradation requires the material to be consumed by microorganisms. This material is ideal for mulch film and products that usually end up as litter.
- Carbonyl Group: Carbon Monoxide Copolymers
It is not known whether carbon monoxide products completely degrade into non-plastic products or whether they simply disintegrate into smaller pieces of plastic.Carbon monoxide copolymers.
- Metal Complexes
Plastics containing metal break down in the absence of light receive enough UV light before burial they can be used in landfills and tree shelters. heavy toxic metal residues such as nickel, cobalt, and iron remain in the soil after degradation.
Biodegradable plastics are polyesters, polyhydroxybutyrates, and vinyl
polymers. They are degraded by microorganisms such as bacteria, fungi, and
algae. Some biodegradable plastics are:
They are the most commonly used and lowest-costing ingredient of all biodegradable polymers.
The starch can be derived from corn, potatoes, and rice. According the to manufacture methods there are:
- Surface-Modified Starch Additive: Starch is treated with a small amount of
an unsaturated fat or a fatty acid oxidizing agent, such as vegetable oil.
- Gelatinized Starch Additive: Gelatinized starch is used in films of polyethylene coacrylic acid (EAA) and in a mixture of EAA and low density polyethylene.
- Thermoplastic Starch Materials: They contain 70-100 percent starch as the base for the
polymer. They have great water-solubility are very easily
consumed by microorganisms.They are indicated for mulch films, bags for animal feed and
fertilizer, and products that will end up in water.
Other degradable plastics are:
- Polyesters: Polyglycolic acid (PGA): Used as a controlled drug release and as material used in cirurgy.
- Polylactic acid (PLA): Produced from fermenting crops and dairy products PLA is used as packaging and paper coatings, sustained release systems for pesticides and fertilizers, mulch films, and compost bags.
- Polycaprolactose (PCL): Its use in agriculture are as mulch, seedling containers and slow release of herbicides to control aquatic weeds.
- Polyhydroxybutyrate (PHB): It is produced by microorganism. It has poor resistance to solvents. Its uses are unknown.
- Polyhydroxyvalerate (PHBV): Its use is limited to medicine and pharmacy because of high production cost, films and paper coating.
Polyvinylalcohol: Used in packaging and bagging applications. It is water soluble.
Polyvilylacetate: Uses are unknown. It is watersoluble.
Polyenlketone: Water soluble with unknown uses.
Polyhydroxyalkanoates or PHAs are linear polyesters produced in nature by
bacterial fermentation of sugar or lipids. More than 100 different monomers
can be combined within this family to give materials with extremely different properties.
They can be either thermoplastic or elastomeric materials, with melting points
ranging from 40 to 180°. The most common type of PHA is PHB
(poly-beta-hydroxybutyrate). PHB has properties similar to those of PP,
however it is stiffer and more brittle.
To produce PHB a culture of a micro-organism such as Alcaligenes eutrophus is
placed in a suitable medium and fed appropriate nutrients so that it
multiplies rapidly. Once the population has reached a substancial level, the
'diet' is changed to force the micro-organism to create PHB. Harvested amounts
of PHB from the organism can be anywhere from 30% to 80% of the organisms dry weight.
A PHB copolymer called PHBV (polyhydroxybutyrate-valerate) is less stiff and
tougher, and it is used as packaging material.
Antimony trioxide is used as a catalyst in the manufacture of PET
(polyethylene terephthalate), plastic bottles. Prof. William Shotyk, Dr.
Michael Krachlerand and co-workers at the Institute of Environmental
Geochemistry, University of Heidelberg found antimony to be leaching to the
bottled drinking water. The antimony content of PET bottled waters increased
in proportion to its storage time.
According to Shotyk and Krachlerand pristine groundwater was found to contain
only two parts per trillion of Sb, with the PET bottled waters typically
showing values a few hundred times greater. This is because PET material contains several hundred mg/kg of the metal whereas rocks and surface soils contain less than 1mg/kg antimony. An alternative to antimony as
catalyst is insoluble titanium which is used in for PET bottles made in Japan. Polypropylene bottles are
manufactured without antimony trioxide. Glass bottles do not leach antimony.
Consumer should therefore buy water filled in glass or PPE (polypropylene) bottles.
Most foods contain very low concentrations of tin. Canned foods may contain
higher levels because the tin coating used to protect the steel body of the
can from corrosion can slowly transfer into the food.
Tin leaching present no health effect on the consumer apart stomach upsets
such as nausea, vomiting, diarrhoea, abdominal cramps and bloating in some
sensitive people at levels above 200 milligrams per kilogram. This is the
maximum legal amount of tin that can be present in canned foods.
Limits for tin for particular categories of cans are:
- 100mg/kg for drinks.
- 50 mg/kg for infant and baby foods.
- 50 mg/kg for dietary foods for special medical purposes intended specifically for infants.
Lacquered cans are used for acidic foods. This avoids tin corrosion but leads
to bisphenol-A leaking. This substance is an endocrine disrupter which
interacts with hormone systems, such as the female oestrogens and male
androgens. No evidence of a link between harmful effects on human reproductive
health and exposure to endocrine disrupters have been reported so far.
Bisphenol A is an endocrine disruptor that affect reproduction and brain
development in animal studies. The effect on humans is not clear yet. It is
being widely used as a monomer for the production of polycarbonate and epoxy
resins for food and beverages plastic packaging and the resin linings of food cans.
Belcher and colleagues found in 2008 that exposure to BPA occurs mainly by
consumption of contaminated foods and beverages that have contacted epoxy
resins or polycarbonate plastics.
According to the authors high temperatures increases the migration of BPA to
food and beverages. The authors found no difference between new and used
bottles. The temperature was found to influence drastically the release of
the chemical. In polycarbonate water bottles, which had not been previously
submitted to heat, BPA was found to migrate at rates ranging from 0.20 ng/h
to 0.79 ng/h. After a brief exposure to boiling water, rates increased to 8 to
32 nanograms per hour.
The authors concluded that BPA migration from polycarbonate drinking bottles
should be included in the total Endocrine Disrupting Chemical-burden
"EDC-burden". Industrial hot bottling of juices and other beverages, widely
used to increase self-life may boost the release of harmful BPA.
Bisphenol A (BPA) is known to be an endocrine disruptor. It found in
polycarbonate bottles release which release BPA to water and other beverages.
It is also found in canned foods leaching from the protective lining of cans,
and many common consumer products. In animals, BPA caused oocyte aneuploidy which is an abnormal number of chromosomes, and is a type of chromosome
abnormality. An extra or missing chromosome is a common cause of birth
defects. BPA also reduced production of oestradiol. Mok-Lin and colleagues
2010 studied the association of urinary BPA and the reduction of number of
oocytes retrieved and peak oestradiol levels.
These findings were confirmed by a study of Fujimoto and colleagues 2010 which
found an inverse association between serum unconjugated BPA concentration and
normal fertilization. [53]
Canned soups increase exposure to bisphenol A [54]
Bisphenol A (BPA) is present as a by-product of interior epoxy coatings used to prevent corrosion. It migrates to the canned food. It is associated with disorders of reproduction, changes in the ADN and may trigger diabetes, cause failures of erection, and influences the cardiovascular system. It may hinder the evolution of the brain of fetuses, toddlers and small children.
Carwile et al. 2011 found that consuming one serving of canned soup per day leaded to 20,8 microgram BPA in urine, after a 5 days trial, while a group which consumed fresh cooked soup had only 1,1 microgram of BPA in urine.
The authors caution that the effect of intermittent elevations in urinary BPA concentration is unknown, however may be important for persons which consume often canned foods. These data should help the implementation of available or proposed alternatives to epoxy resins linings for most canned foods. Bisphenol A is used extensively in
the plastic lining in food cans. The National Toxicology Program published in
April 2008 a statement concluding that there was some concern for neural and
behavioural effects in foetuses, infants, and children at current human
exposures to BPA. There are evidences that the compound induces cancer at
current exposure levels.
As a precautionary measure NTP recommends to "reduce the use of canned
foods, and, when possible opt for glass, porcelaine or stainless steel
containers, particularly for hot foods or liquids."
The Environmental Working Group (EWG) had reported in 2007 that BPA could
leach into canned food at levels reaching 200 times the acceptable amount.
[56]
These findings are backed by the study of the Center for the Evaluation of Risks
to Human Reproduction CERHR Expert Panel on Bisphenol A
[57]
FDA is now being requested to set the maximum level for regulatory use.
In Europe the EFSA hat set a tolerable daily intake (TDI) level for BPA of 50
micrograms/kg body weight/day. Iain A. Lang and colleagues 2008 examine associations between urinary
Bisphenol A (BPA) concentrations and adult health status using data from the
National Health and Nutrition Examination Survey 2003-2004. Bisphenol-A is one
of the world's highest production-volume chemicals, with more than 2 million
metric tons produced worldwide in 2003 epoxy resins lining food and beverage
containers and as a monomer in polycarbonate plastics in many consumer products.
The authors found that higher urinary concentrations of bisphenola A (BPA) were
associated with an increased prevalence of cardiovascular disease, diabetes, and
liver-enzyme abnormalities , such as elevated gamma-glutamyltransferase and
alkaline phosphatase. They stress that adverse effects of low-dose BPA in animals
have already been found in studies on animals, and call for more studies on this
subject.
The American Chemistry Council, an organisation of the chemical industry and
the Polycarbonate/BPA Global Group, writes in its site www.bisphenol-a.org
that the US National Toxicology Program's (NTP) final report on bisphenol-A
found no direct evidence for health effects in people.
However, the final conclusion of NTP report says that there is some concern
for neural and behavioural effects in fetuses, infants, and children at
current human exposures. The NTP also has some concern for bisphenol A
exposure in these populations based on effects in the prostate gland, mammary
gland, and an earlier age for puberty in females. The Panel considered the significant
differences between humans and rodents, such as the fact that people metabolise and excrete BPA
far more quickly than rodents. This body of evidence further limits the
relevance of low-dose effects of BPA reported in some rodent studies used for
human risk assessment.
In its previous risk assessment, the Panel derived a TDI of 0.05 mg/kg body
weight based on the no-observed-adverse-effect level (NOAEL) of 5 milligram/kg
body weight/day for effects in rats and included an uncertainty factor of 100.
In this latest assessment, the Panel concluded that this TDI provides a
sufficient margin of safety for the protection of the consumer, including
foetuses and newborns.
EFSA NOAEL setting for bisphenol is in conformity with different studies on this
matter, such as the report of the Norwegian Scientific Committee for Food
Safety, (VKM, 2008), which concluded that the findings did not provide sufficient
evidence for setting a robust lower NOAEL than the current NOAEL set by EFSA at 5
mg/kg body weight/day. [62] [63] [64]
Lang an colleagues 2008 raises suspicion that higher urinary bisphenol A (BPA)
concentrations were associated with cardiovascular diagnose. diabetes but not
with other studied common diseases and that higher bisphenol A concentrations can
be associated with clinically abnormal concentrations of the liver enzymes
gamma-glutamyltransferase and alkaline phosphatase. The authors concluded that
higher bisphenol A exposure, reflected in higher urinary concentrations of
bisphenol A, may be associated with morbidity in adults.
A Statement of the European Food Safety Authority (EFSA) related to the Study
of Lang 2008 correlating urinary bisphenol A concentrations to medical
disorders in adults, concluded that there is no need to revise the 2006 TDI of
bisphenola A of 0.05 mg/kg body weight (bw)/day.
The EFSA says that the study of Lang 2008 uses of the existing US National
Health and Nutrition Examination Survey (NHANES) for 2003-2004 (CDC, 2004),
which comprises measurements of BPA in urine samples of individuals.
[67]
These data have no information on exposure during the time needed for development
of diseases. The observed association between urinary BPA elimination and the
conditions mentioned above may have been a chance finding or may be due to
non-identified confounders.
The EFSA concludes that this single study does not provide sufficient proof for a
causal link between exposure to BPA and the health conditions mentioned above.
Therefore, EFSA considers that there is no need to revise the TDI as derived by
the AFC Panel in 2006.
In October 2011 California adopted the Toxin-Free Infants and Toddlers Act. Ten other states had already restricted the use of BPA in food contact materials. The California forbids the use of bisphenol A in bottle or cup which come in contact with food. Deadline is July 1, 2013. Detectable levels of BPA in these products may not exceed 0.1 part per billion (ppb). Canada and the European Union banned bisphenol A in Baby bottles,
BPA acts similar to the hormone oestrogen and is therefore linked to heart disease, reproductive problems, behavioural problems and breast and prostate cancers, it disruptes human development and making it particularly potent for children. Food industry criticised the studies and arises doubts on conclusions concerning safety of the substance.
The US FDA does not ban the chemical from food and beverage containers, following a settlement to a lawsuit filed in August by the National Resources Defense Council. FDA notes that their position was not a final safety determination and the agency will continue to support research examining the safety of BPA.
Bisphenol A (BPA) is an industrial chemical that has been present in many hard plastic bottles and metal-based food and beverage cans. Studies have thus far supported the safety of current low levels of human exposure to BPA. However, on the basis of results from recent studies, both the National Toxicology Program at the National Institutes of Health and FDA have some concern about the potential effects of BPA on the brain, behaviour, and prostate gland in foetuses, infants, and young children. The agency is trying to clarify uncertainties about the risks of BPA. The agency supports actions to stop the use of BPA in Baby bottles and cups, develop alternatives to BPA for the linings of infant formula cans and other can linings.
Despite the concerns on BPA, the agency is not recommending that families change the use of infant formula or foods, as the benefit of a stable source of good nutrition outweighs the potential risk from BPA exposure.
Ferguso, Law and Abshire, in a study of 2012 at the National Center for Toxicological Research in Jefferson, Arkansas, report that dams and offspring receiving bisphenol A in their diet, presented shorter turning latencies and with age decreasing latencies of males. Preweaning body weights were reduced No other alkterations were noted and the authors concluded that BPA treatment at these doses has no effects on gestational or lactational body weight, offspring anogenital distance, preweaning behaviours or hormone levels and whole and regional brain weights measured at weaning.
According to Linda Birnbaum, head of the National Institute of Environmental Health Sciences (NIEHS), new findings do not reduce the concern regarding BPA in prenatal development, infants and young children. [71]
Cabaton et al. 2011 in a study at the Tufts University, reports that perinatal exposure to BPA leads to a dose-dependent decline in the reproductive capacity of female mice, suggesting the possibility that early BPA exposure may also affect reproductive capacity in women. [72]
Urinary BPA levels were found by Shankar and Teppala 2011 to be associated with diabetes mellitus. More studies are needed to confirm or disprove. [73]
Huff, Jacobson and Davis 2008 write in a commentary that two years animal
testing of industrial chemicals and food additives is not long enough.
According to the present praxis the chemicals are administered to lab rodents
beginning shortly after birth and ending after two years.
According to the authors practically all rodent tests submitted to regulatory
agencies are insufficiently sensitive. The authors argues that those tests
sometimes understate human risks and should start in utero and continue as long
as three years, the approximate life spans of rats and mice.
The paper highlights rodent tests on several chemicals that did not appear to
be carcinogenic after two years, but did so in longer studies.
For instance, two-year rat tests on the artificial sweetener aspartame did not
detect any tumors, but two tests, one of which began in utero, that monitored
rats until they died showed increased lymphomas, leukemias, and kidney and
other tumors. Two-year rat tests of the metal cadmium, which is used in
batteries and other products, did not find the substance to be a carcinogen,
but a two-and-a-half-year study found lung tumors. Similarly, two-year testing
in rats of the solvent toluene did not detect cancer. But significant numbers
of cancers did appear in animals exposed to toluene for two years and then
allowed to live an additional six months.
Since exposure to many chemicals occurs before birth, tests on rodents should
begin in utero, particularly for chemicals that may interfere with the
endocrine and reproductive systems. The Food and Drug Administration normally
requires such tests on potential food additives.
The paper cited bisphenol A, or BPA, as an example of a chemical that should
be tested on animals before and after birth. BPA is widely used in plastic
bottles and in the lining of metal cans, and has been increasing in the diets
of infants and children. Fetuses are particularly sensitive to chemicals like
BPA, which is an endocrine disruptor. Several governments have recently acted
to restrict its use.
The authors recommend that government agencies involved in testing, including the
Food and Drug Administration, Environmental Protection Agency, Occupational
Safety and Health Administration, Consumer Product Safety Commission, and
National Toxicology Program compare the results of two-year and longer-term
animal studies and then revise their "best practices." This is strongly supported
by the CSPI. [75] Despite problems of materials leaching from PET (polyethylene terephthalate)
bottles, they are still predicted to dominate drinks packaging markets.
Growing beverage market leads to an increase of PET bottles on market. Atmospheric oxygen permeability is a problem to producers reducing self-life. Looking for test procedures for the determination of the stability and/or
durability of beverages in plastic packaging. WILD developed a test procedure
which simulates reality of a typical several month storage on the product
quality within less than three weeks, the test being suitable for al kinds of
passive barrier packaging.
Latex proteins are used in packaging material transferred to food in some
cases, according to the study by Leatherhead Food International working for FSA.
There are four major latex allergens: Hev b5 and Hev b6.02 , Hev b1 and Hev
b5. No safe level oif latex are defined, but it seems that small traces can
trigger an allergic reaction. Labelling of the latex content in packaging
material is being proposed by some groups.
It wasn't clear from the research that allergens were being transferred from
latex packaging to food. More work is required to accurately measure the
levels of latex in food and the FSA is doing researche work on the matter. [77]
UK FSA released a report on 19 January 2005 on the assessment of latex
protein transfer from contact materials into food and drink products.
According to the Agency the study indicated the presence of one or more of
the latex allergens in 7 out of 21 commercial packaging materials (e.g.
chocolate bar and ice cream wrappers).
Low levels of latex allergens (Hev b3 or Hev b5) were found in 3 of the 7 foods tested.
This research has shown that latex allergens may be present in some food
packaging materials and that there is the possibility of transfer from the
material to the food. A modified ELISA method has been developed to detect and
quantify latex allergens in packaging and foods. Further work is required to
improve this method to make it a fully validated, quantitative, robust
analytical technique. Latex allergen transfer has serious implications for
some individuals.
Another research project of April 2006 will build on previous Agency-funded
work (A03043) through development of an improved, validated enzyme linked
immunosorbant assay (ELISA) that is robust and reliable. This assay will be
used to determine the presence of latex allergens in food contact materials
and associated foods.
Project A03043 included a review on the type and extent of latex protein
containing material used industrially. Latex allergens were present and
detectable in food packaging materials.
However, Hev b1 and Hev b3 proved difficult to extract from food matrices and
measurement of these allergens in food could only be considered as
semi-quantitative at best. Overall, the results indicated that further
technical work was required to develop reliable and robust validated ELISAs
for the quantitative recovery of latex allergens, especially Hev b1 and Hev
b3. The most relevant matrices were identified as confectionery, dairy and
pastry products.
The modified ELISA protocol will be re-established in the laboratory and used to
measure allergen levels in representative batches of cold seal adhesive and
bakery release films. The project will try to increasing the recovery of Hev b1
and Hev b3 from selected confectionery, dairy and pastry products. Validation of
the new extraction and ELISA protocol will follow.
The Guide to Evolving Packaging Design published by Waste and Resources Action Programme (Wrap) is focused on retailers and manufacturers. Important companies have signed commitment to cut down on packaging going to landfill. [80]
Retailers can push their suppliers to reduce the amount of material used or moving to more recyclable, reusable and biodegradable materials.
New annual targets set by UK regulations increase manufacturers' obligations to the market to recover and recycle their packaging under international and European pressure on the UK to decrease carbon emissions.
Reducing the weight of beer bottles spares glass and transport costs. Other companies changed from glass to plastic bottles and succeeded to set it on market.
Experts should bear in mind that migration of pasticizers and other unwanted chemicals takes place from the plastic bottle to the food, which is not present when glass is used. The oxygen barrier is not as perfect as the 100% barrier of glass bottles.
Another idea was to use different containers for similar products simplifying processes.
The regulations allow accredited waste reprocessing companies to sell Packaging Waste Recovery Notes (PRNs) for every tonne of packaging waste they recycle. Companies with 2m pounds sterling turnover or handling in excess of 50 tonnes of packaging a year meet their obligation, assessed under the scheme, by buying PRNs.
The profits are reinvested in the recycling infrastructure. This resembles the European Green Dot, where all packaging pay fees for the recycling. This system is not compulsory in UK. [81]
Estrogenic effects of food wrap packaging [82]
Estrogenicity of xenoestrogens found in food wrap packaging and phytoestrogen flavonoids. Uterotrophic and vaginal cornification assays were studied on rats by Stroheker and colleauges in 2003. Genistein, bisphenol F, and octylphenol were identified as estrogenic only in immature rats. While apigenin and kaempferol appeared to have low estrogenic activity, they potentialized the uterotrophic effect of 17 beta-estradiol in immature rats.
In this study the authors found that phytoestrogens like genistein can be as potent or even more estrogenic than compounds found in food wrap packaging. Tha authors suggest the vaginal cornification to used as a sensitive and useful test to detect weak estrogenic compounds to which humans can be exposed via food.
Plastics in the oceans
present a hazard to animals by swallowing it or becoming trapped in nets or
other plastic artefacts. Littered plastic waste form the Great Pacific
Garbage Patch between California and Hawaii. A report by Katsuhiko Saido and
colleagues 2009 at the National Meeting of the American Chemical Society (ACS)
adds another hazard to marine life.
The study says that polystyrene,
such as Styrofoam, littered in the sea, begins to decompose within one year
releasing chemicals which are further degraded in water and by living
organisms. Mainly BPA and PS oligomer are of concern. They are not found in
nature and appeared with the start of the plastic chemistry. Both substances
disrupt the functioning of hormones in animals, affect reproductive systems
and cause other health effects. BPA is also being released by linings of cans.
The researchers developed a method to simulate the breakdown of plastic products
under oceans conditions releasing the carcinogen styrene monomer, and two
suspected carcinogens styrene dimer and styrene trimer.
Coating packaging with whey protein is being developed to provide an oxygen, moisture and odour barrier. Whey is a by-product of the production on cheese.
Its use may improve the ability of recycling the plastic. Oxygen barriers made
of polyolefin films such as polyethylene (PE) and polypropylene (PP) are
laminated with synthetic polymers like ethylvinylalkohol (EVOH) and
polyvinylidenchlorid (PVDC) copolymers. The different layers are very
difficult to separate and have therefore a poor recyclability.
Whey coated materials will be low in cost and will be recyclable by chemical
of enzymatic removal of the whey layer. The research is made by the WHEYLAYER
project, run by IRIS and is sponsored by the European Union.
Searching for alternatives to petroleum-based packaging such as polyethylene
terephthalate (PET)
supermarket chains Sainsbury from UK and Delhaize from Belgium move its
private label products to biodegradable packaging in an effort to reduce
rubbish collected for landfill.
Justin King of Sainsbury called on government to ensure that every home in the
UK has a compost bin. Degradable plastic is made from oil a fossil fuel with
additives to enable it to break down to CO2 plus water. Compostable sugar
cane trays, and the use of polylactic acid (PLA) packaging for punnets or
pallets. Polylactic acid is a corn-based biodegradable polymer made by
NatureWorks, a part of Cargill, are being tested.
PLA is already used in many fields: disposable Dixie cups, dishware, forks, knives and
spoons that are used only once, then thrown away. precut salads, fruit, vegetables and convenience
store and fast food restaurant bought fountain drink cups. vinegar, water, milk, juice et
Biodegradable packaging decompose in 2 years. Traditional non-biodegradable
packaging takes more than 200 years to return to the earth and creates harmful
greenhouse gases when burned. [85]
[86]
PHB polyhydroxibutirate new plant operations
planned to start in 2008, the new plant will produce Biocycle, a biodegradable plastic using sugar as raw material
The Pedra Sugar Mill, in Serrana, in the region of Ribeirão Preto, in the State of São Paulo, is Brazil produces. Polyhydroxibutirate, sugar-derived plastic under the Biocycle trademark.
The pilot plant produces 60 tons of Biocycle a year.The entire production is exported to companies in the United States, Japan and Germany PHB is biodegradable. Packing made with PHB is degraded into water and carbonic gas in six to 12 months.
According to the producer, a kilogram of the sugarcane polymer costs US$ 5, whereas a kilogram of other biodegradable plastics, made from beet or corn, for instance, costs US$ 14.
According to Jefter Fernandes do Nascimentooday the world produces 200 million tons a year of polypropylene. PHB is not indicated to replace all the uses of polypropylene, but in the next years it will take between 1% and 2% of that market.
A packaging for eucalyptus seedlings made with PHB plastic were launched. Three months after the seedling has been planted the PHB degrades into the soil. Productivity increases at paper and pulp plants farms.
A research group from the Institute of Biomedical Sciences (Instituto de Ciencias Biomedicas, ICB), of the University of São Paulo (Universidade de São Paulo, USP), led by biologist Ana Clara Schemberg, selected the bacterium -
Alcaligenes eutrophus, found in sugarcane fields soil - and produced a transgenic variety that is more efficient in synthesizing PHB.
The process in stages organizes the plant's operation, which is divided into three main blocks: fermentation, in which the bacteria reproduce and synthesize the polymer; extraction, in which the polymer is taken out of the bacteria; and purification and drying, in which the organic residues - in other words, bacteria remains - are eliminated from the polymer. The selling of eucalyptus seedlings placed in PHB packaging promising cost reduction and productivity gains since the seedlings are planted directly into the soil, the elimination of handling prevents contamination, which affects 20% of the plants when conventional tubets are used.This will be extended to coffee, pupunha (known as spiny peachpalm) and papaya seedlings. [87] [88]
Mouldy off-flavour can be caused by 2, 4, 6 trichloranisol and is found in
foods like wine raisins, ethereal oils, bottled mineral water and others.
The sources of trichloranisol are various. Aung and colleagues, for example,
demonstrated that sterilized raisins formed trichloranisol under low water
activity nonconducive for microbial activity. [89]
There are many sources of trichloranisol in wine. The best known cork oak forests are located at the
Mediterranean region, comprising large areas of Algeria, Tunisia, Morocco, southern Europe
including Italy, Portugal, Spain and France. The cork oak develops a thick
bark of cork. Trichloranisol content of the bark is relatively low, but
increases in the lower part of the trees, as it nears the ground. Humidity
increases near the ground triggering mould activity. That is why near the
ground yellow colouration of cork an and trichloranisol content rises. The most frequent source is the transformation of
chlorphenols by several types of moulds. Chlorphenols are used in agriculture
as pesticide, in packagings, in the wood industry and in cork forestry. The EU
forbids therefore the use of pesticides in cork oak plantations. Chlorine can come from residues in cork and wine barrels.
Cork is bleached and wood barrels are treated with sodium hypochloride.
Blanching of cork is now being done with hydrogen peroxide. Trichloranisol may heavily contaminate
the atmosphere of the wine cellar and migrate to the stored wine. Trichloranisol has already been found in
bottles with crown cape and glass plugs. In these cases the corkiness
off-flavour had been originated before bottling. Wood barrels might be the reason.
Analytical quality control tries to sort out high trichloranisol charges of
cork. Water steam treatment and even microwave oven were seen to remove
trichloranisol, however other valuable odour and flavour components were also
removed.
According to Eleanor M. Snowdon and colleagues mousy off-flavour occurs when
wines are infected with either lactic acid bacteria or Dekkera/Brettanomyces.
Snowdon write that 2-ethyltetrahydropyridine, 2-acetyltetrahydopyridine, and
2-acetylpyrroline are responsible for the off-flavour.
The authors say that the microbe's metabolism probably plays a key role in
mousy off-flavor formation, and that oxygen may play a key role. A wine infected
with Dekkera/Brettanomyces in the absence of oxygen may not become mousy unless
exposed to oxygen via a processing or handling procedure
.
Koni Grob and colleagues 2006 tested the migration of plasticizers from PVC
gaskets into oily foods packed in glass jars oil at standard conditions
(pasteurization/sterilization followed by 10 days at 40°), and found
migration far below that observed in reality; after 20 days at 60°,
migration was above average in reality, but still did not reach the worst case
required by legislation. ESBO, DEH, DEHS and ATBC, Citroflex A were included
in testing. [91]
Ezerskis and colleagues 2007 tested foods and gaskets and found epoxidised
soybean oil (ESBO) to be the principal plasticiser in 53% of the tested
gaskets. Polyadipate in 27% and Diisodecyl phthalate (DIDP) in 20%.
ESBO
hat the highest migration rate, with concentrations in food up to 281.9mg/kg
(max allowed= 60 mg/kg).
The authors found also high migration rates of di-(2-ethylhexyl) phthalate
(DEHP), up to 8.7 mg/kg (max allowed=3 mg/kg) in 40% of the food samples.
Total polyadipate (PA) concentrations of 16.3 mg/kg in average (maxPA allowed=30 mg/kg) were found to be acceptable.
The authors suggest the polyadipates, having the lowest migration rates of the
tested platicisers, as plasticisers for PVC gasket seals used in food
industry. [92]
Koni Grob and colleagues 2007 support the findings of studies saying that
polyadipates seem to be the only acceptable plasticizers for PVC gaskets. They
suggest dilute the plasticizers with others of low viscosity for a better
handling. According to the authors storage test for two years showed
migration of polyadipate clearly below the limits and the migration of ESBO
was found several times higher. [93]
According to Koni Grob and colleagues 2006 epoxidized soy bean oil (ESBO) was
found to be toxic for rats, but the toxic constituent is unknown. Analysing
the components of ESBO the authors found a possible effect of epoxy oleic
acid to be negligible. Diepoxy linoleic acid was found similar to the
exposure from oxidized fats and oils of normal diet. Only triepoxy linolenic
acid from ESBO exceeds that from normal food by around two orders of
magnitude. The authors suggest therefore the use of an epoxidized edible oil
virtually free of linolenic acid.
Koni Grob and colleagues 2005 wrote that the migration of epoxidized soy bean
oil (ESBO) from the gasket in the lids of glass jars into foods, particularly
those rich in edible oil, often far exceeds the legal limit (60 mg/kg) and
propose a method of testing ESBO in foods. According to the authors the new
method has a detection limit between 2-5 mg/kg, depending on the food, with
uncertainty of the procedure being below 10%.
Recycled paper and cardboard may contain toxic inks, adhesives and other dyes
which may migrate to foods like pizzas, curry sausages which heat up the
cardboard. For this reason recycled materials are not permitted in pizza boxes
in Italy. Phthalates such as diisobutyl phthalate were found in pizza boxes in
2008 by Monica Bononi using a new developed testing method for phthalate
migration in paper and cardboards.
The new method is a useful tool for the packaging industry to measure the
amount of DIBP emanating from recycled cardboard, paper and seals for caps for
glass jars.
German manufacturers and processors of paper and cardboard recently decided to
stop using products containing DIBP due to safety concerns.
The Australian consumer group CHOICE found in June 2008 that more than half
of baby foods in jars were contaminated by phthalate used as plasticizer in
the seal of the cap. The group says that there is no immediate health danger
to individuals, however, it is the long-term health implications of
plasticisers migrating into foods which is of concern.
CHOICE calls for the food industry to find safe alternatives to epoxidised
soybean oil(ESBO) and phthalates, and regulators should sets limits for
plasticisers in food. [97] A single analytical procedure is presented for determination of so-called
monomeric plasticisers such as di(2-ethylhexyl) adipate, polymeric
plasticisers such as poly(butylene adipate), and secondary plasticisers such
as epoxidised soybean oil, in stretch-type films. The combined method offers
significant savings in time compared with the separate analytical methods
published earlier for monomeric and polymeric poly(vinyl chloride) plasticisers.
The European Food Safety Authority (EFSA) evaluated in May 2004 the dietary risk of epoxidised soybean oil (ESBO) used as plasticizer and stabiliser in
polyvinyl chloride (PVC) gaskets of metal lids used to seal glass jars and
bottles for baby foods packed in glass jars and bottles, and considered the
formation of derivatives of ESBO such as chlorohydrins, which may occur as the
PVC is heated to high temperatures.
The estimated exposure of infants aged 6-12 months to ESBO migrating into baby
foods packaged in glass jars and bottles with metal lids sealed with PVC
gaskets can sometimes exceed the Tolerable Daily Intake (TDI) of 1 mg/kg body
weight by up to 4- to 5-fold. Since there is an inbuilt safety factor of more
than 100 in the derivation of the TDI, exceeding the TDI by 4- to 5-fold does
not imply that there will be adverse health effects in infants. Moreover, the
Panel notes that ESBO is neither carcinogenic nor genotoxic. However, such a
situation is undesirable because it could reduce on a regular basis the safety
margin between exposure and adverse effects.
The Pannel recommends to develop a specific migration limit for ESBO in baby
foods, derived from the TDI of 1 mg/kg body weight for infants of 6 months of
age, weighing 7.5 kg, fed mainly or exclusively on processed baby foods.
The Pannel cannot give an advice on the significance for health of derivatives of ESBO in foods because of absence of toxicological data. The
Pannel stresses that up to 5% of the fatty acids in ESBO in gaskets is
converted into derivatives. The Pannel calls for further analytical and
toxicological data on ESBO derivatives. According to EFSA 2006, ESBO is used up to 40% in PVC gaskets of metal lids of
glass jars and in PVC cling film up to 10%. The overall exposure from these
applications is compared to the TDI of 1 mg/kg bw for ESBO set by the SCF (SCF,
1999)
.
The plasticiser di(2-ethylhexyl)adipate (DEHA) is frequently used in combination
with ESBO in cling films. Like ESBO, DEHA is practically insoluble in foods with
no fat and so migrates only into fatty foods. Finally, DEHA is a much smaller
molecule than ESBO and so its tendency to migrate from cling films is higher than
ESBO. As a consequence of these factors, it can be concluded that consumer
exposure to ESBO migration from cling films will
be no greater than exposure to DEHA. The metabolite of DEHA found in urine of
adults is 2-ethylhexanoic acid (2-EHA).
The Scientific Panel on Food Additives, Flavourings, Processing Aids and
Materials in
Contact with Food (AFC) evaluated the risk of adults resulting from the
migration of epoxidised soybean oil (ESBO) into foodstuffs such as
sauces,condiments and products in oil packaged in glass jar with metal lids
lined with polyvinyl chloride (PVC) containing ESBO.
ESBO can be present up to 40% of the weight of the gasket and is also used
plasticised PVC cling films for wrapping foods.
Because of the high migration figures, an estimation of the exposure of adults to
ESBO was necessary in order to find out if the TDI of 1 mg/kg body weight set by
the Scientific Committee on Food (SCF, 1999) was exceeded. The Pannel concluded
that the potential high dietary exposure of adults was estimated to be 0.25 mg/kg
bw/day, and that the potential dietary exposure of adults to ESBO from foods
packaged in cling films will not exceed 0.2 mg/kg bw/day, and that the potential
dietary exposure of adults to ESBO from foods packaged in glass jars and in cling
films is below the TDI of 1mg/kg bw as set by the SCF (SCF, 1999). The Panel
considered therefore that further refinement of the exposure estimates was not
necessary.
Official method for compliance testing of lids is dissatisfying
[101]
Koni Grob and colleagues 2008 says that the official method for
testing migration from the gaskets of lids into oily foods is not suitable for compliance
testing of lids.
A glass jar containing oil is closed with the caps to be tested, turned on its
lid and heated 1 hour at 100° and 1 hour at 130°, simulating pasteurisation
and sterilisation respectively. Prediction of migration during 5 years storage is
performed measuring the migration after 10 days at 40°. Keeping the jar turned on its lid gets the
whole content of the jar in contact with the lid and equilibrium of migration is completed involving all oil and not just 30 ml sticking to the lid under
normal conditions.
Speed of migration at 40° accelerated only by a factor of 2.4 the platicizer
such as ESBO and and 3.9 for polyadipate, variation occur with the oil used,
while migration measured with coconut oil being 2-3 times that with olive oil.
ESBO was found by the authors to be left behind a layer of PVC which stops
the migration during the test.
The authors concluded that the described official method is not suitable to
extend the 10-day testing to a prediction for years in general manner and they
call for testing under a more realistic scenario. [102]
Charles Onwulata 2007 looked for the use of whey, a byproduct of cheese production. He developed a way to use it in the production of candy, pasta, animal feeds and a process called reactive extrusion to supplement polyethylene with whey proteins.
Reactive extrusion involves forcing plastic material through a heating chamber, where it melts and combines with a chemical agent that strengthens it before it's molded into a new shape. Onwulata and Seiichiro Isobe combined whey protein isolate, cornstarch, glycerol, cellulose fiber, acetic acid and the milk protein casein, creating a biodegradable plastic product that can be mixed with polyethylene.
Bioplastic blends can only replace about 20 percent of the polyethylene in a product, is only partially biodegradable. However, Onwulata and his colleagues, looking for completely biodegradable bioplastics are experimenting with polylactic acid (PLA).
Polylactic acid (PLA) is a commercially available biodegradable polymer derived from lactic acid and is used in many nonfood products as an alternative to petrochemical-derived polymers. PLA substituted with starch-whey concentrates and casein blends (DPB) may enhance the properties of this polymer. Onwulata says that dairy proteins, whey and casein, may provide an advantage by lowering the molded product peak temperature of PLA allowing for more biomaterials to be used in a formulation. [103]
Onwulata 2006 evaluated the properties of several blends of extruded agricultural materials and found that the properties of extruded blends in pellet form made from milk protein, casein and whey protein isolates, starch and glycerol milk protein based (MPB) were most suitable as feed material for injection molding. Injection molded MPB cups demonstrated that agricultural materials based on dairy ingredients can be processed directly in equipment used by the plastics industry. [104] BASF will increase its production of biodegradable plastics up to 60.000
Tons/year by 2010. Ecoflex, a is petrochemical-derived, fully biodegradable,
complying with DIN EN 13432 (requirements for compostability) and Ecovio is
45 per cent polylactic acid- based. It is being increasingly sought after by
food processors as both a renewable and bio-based source of packaging
coatings. Both product rages are petrochemical based. Starch substitutes only
partially the oil derivates.
According to BASF the materials are used to make carrier bags, compostable can
liners, mulch film, food wrapping, and for other applications. Both properties
- biodegradability and a high renewable raw material content - are increasingly
sought after in the competitive global materials market.
Biodegradable and renewable packagings face almost threefold prices compared with
traditional plastics. The requirement of full compostability in 90 days according
to DIN EN 13432 must be fulfilled. Last but not least only 45 per cent comes
from renewable sources. 55% are still petrochemicals.
Waste and Resources Action Programme (WRAP) works in partnership to encourage
and enable businesses and consumers to be more efficient in their use of
materials and recycle more things more often. This helps to minimise landfill,
reduce carbon emissions and improve our environment. Important issues are
reducing weight of packaging material, changing to 100% recyclable carton.
Redesigning packaging current packaging can improve food protection and
reduces costs, such as happened with the introduction of the light glass bottle.
Bioplastics are produced from renewable raw materials which capture carbon
from the atmosphere by plants. Incinerating or composting biopackaging this
renewable carbon is returned to the atmosphere.
Fossil fuels is needed in the production of biopackaging, therefore it is not
free of additional co2 emission. Bioplastics presents a potential to reduce
the dependency on crude oil and reduce greenhouse gas emissions.
Composting could produce humus in arid-zones as an additional advantage as
fertiliser and substrate in soil.
Opening up these composting systems for biopackaging, is another way of closing
the loop for these innovative packaging solutions. In addition, composting
systems are economically very competitive compared with incineration. The
generated compost can be used to increase the carbon content in the soil and to
maintain soil fertility.
- The use of renewable resources for their production It is
subject to individual interpretation how big the share of renewable resources in a plastic
product has to be in order to be called a bioplastic. No standard is available to
approve this.
- Their biodegradability / compostability It can be
assessed through the European norm EN 13432, (2000). This norm is used by the association European Bioplastics to approve plastic products if the marketer
advertises the product to be "compostable" or "biodegradable".
According to European Bioplastics
plastic bags and other products, e.g. agricultural mulching foils, made with
polyethylene (PE) with the claim of being "degradable", or "bio-, UV- or
oxo-degradable", and sometimes even "compostable"" do not fulfill this
standard and were lawsuited.
The Environmental Agreement (EA) in the form of a unilateral self-commitment by
industry ensures the keeping of an internationally recognised standard for the
biodegradation of polymers, produced from both, renewable or fossil resources.
According to Bioplastics the production will tend to
biobased/non-biodegradable plastics in near future, however, the barrier
properties and heat resistance must be improved. Usual polylactic acid (PLA)
softens at a temperature of about 60° and is not deployable for several
applications. New PLA is being developed from D- or L-lactic acid to resist
heat up to 175°.
Due to a low CO2-barrier carbonated beverages lose their sparkling character very
soon at the moment. Furthermore, the high permeability of steam reduces the
shelf-life. However, it is expected
that new PLA types and barrier layers will widen the scope of applications very soon.
A new polylactic acid (PLA)-based resin from Cereplast, inc. withstands
temperatures as low as -35°, compared to about 20° for standard
PLA-based plastic with good structural properties. [109]
Brazil Braskem will strengthen their production of polyethylene from sugar cane,
so-called "green PE".
The directive includes several requirements to reduce the organic component of
waste. It permits explicitly the burning, the treatment in a mechanical
biological facility and the mixed composting of organic waste components, but
that the waste can no longer be used for soil improvement.
Like the EU parliament and the "biowaste coalition", comprising 12 European
countries, the European Bioplastics supports the idea of a dedicated Organic
Waste Directive that is unfortunately not yet on the agenda of the EU Commission. [108]
German government acknowledged the environment friendly potential of
biopackaging with the amendment of the Packaging Ordinance by releasing
bioplastic bottles from deposit obligation. The ordinance states that bottles
with more than 75 percent RRM content will not be charged with a deposit fee. The
privilege postpones the obligation of installing recovery systems to a point of
time after market introduction. [111]
Lester and colleagues 2010 stressed that vitamins are biosynthesized in
plants by light conditions even at 4 degrees C. The authors report that
top-canopy spinach leaves had higher concentrations of all bioactive
compounds, with the exception of carotenoids, than bottom-canopy leaves.
Spinach stored at 4 degrees C under continuous artificial lighting, had
higher levels of bioactive compounds except beta-carotene and violaxanthin,
compared with spinach leaves stored in dark, which had declining or unchanged
bioactive compounds.
The authors concluded that spinach exposed to continuous light at 4 degrees C,
in clear plastic containers, is more nutritious than leaves kept in dark. [113]
Edible films and coatings are being developed to extend shelf life of ready to
eat foods, improve colour, flavour, texture, and the nutritional value of
fresh-cut fruit and vegetable Maftoonazad and Badii 2009 define edible films as usually made of naturally occurring polymers and functional ingredients formed
on the surface of food products, have acceptable sensory characteristics,
appropriate barrier properties (CO2, O2, water, oil), microbial, biochemical and
physicochemical stability, be safe, and be produced by simple technology in low
cost, and may carry antioxidant, flavour, colour, nutritional or anti-microbial
additives.
A cheese coating enhances the quality of the natural ripening by offering
protection against fungi and yeasts and control of moisture loss without
affecting the ripening process. Varied coatings for cheese are known, such as
water soluble ones using polyvinylacetate copolymers, or waxes. Natamicine is
often added.
Cerqueira and colleagues 2009 studied the effect of chitosan, a galactomannan
from Gleditsia triacanthos, and agar from Glacilaria birdiae, with the addition
of plasticizer and corn oil as nontraditional coatings for cheese.The solutions
of 1.5% of galactomannan, 2.0% of glycerol, and 0.5% of oil presented the best
properties for wettability, water vapour permeability, oxygen and carbon dioxide
permeabilities and opacity values. Mould growth was pronounced on the uncoated
cheese compared with the coated cheese. The authors concluded that the tested
coatings may become an alternative to synthetic coatings.
Duan and colleagues 2010 tested various edible coatings to preserve quality of
pre-washed fresh blueberries under storage conditions. Chlorinated water at a
concentration of 2 ml/litre was used. Semperfresh, a commercial coating,
decreased weight loss of berries. Calcium caseinate coating delayed ripening
during storage. Coatings of acid-soluble chitosan, water-soluble chitosan and water-soluble chitosan + Semperfresh reduced the decay rate of blueberries during
room temperature storage without affecting antioxidant capacity and total
phenolics content of blueberries. Non-vented containers presented better results
compared with vented containers. To increase shelf life of fresh chicken eggs for export Biladeau and Keener 2009
tested food-grade coatings of paraffin wax, mineral oil, soy protein isolate,
and whey protein isolate. Coated eggs presented overall better quality than
uncoated eggs. The authors stress that oil-, wax-, and whey protein
isolate-coating extend shelf live of fresh eggs beyond 6 weeks.
Lee and colleagues 2003 report that the shelf life of minimally processed apple
slices may be extended to 2 weeks when stored in packed trays at 3 degrees C
using a preservation treatment composed of whey protein concentrate (5 g/100 mL)
containing ascorbic acid (1 g/100 mL) plus CaCl2 (1 g/100 mL). Ascorbic acid acts
as antibrowning and calcium chloride inhibits the loss of firmness.
Juck, Neetoo and Chen 2010 developed an antimicrobial edible coating
formulations to control the growth of Listeria monocitogenes on turkey
products. The authors found the most effective poached and processed turkey
treatments to be sodium lactate (2.4%)/sodium diacetate (0.25%) and Nisin
(500IU/g)/sodium lactate (2.4%). The samples, inoculated with Listeria
monocitogenes, were stored for 7 Days at 22 degrees C. Alginate coatings
supplemented with sodium lactate (2.4%)/potassium sorbate (0.3%) delayed the
growth of L. monocytogenes on turkey products stored 8 weeks at 4 degrees C.
The authors concluded that alginate-based antimicrobial coatings enhance the
microbiological safety and quality of ready-to-eat poultry products during
chilled storage.
Neetoo, Ye and Chen 2010 highlight the high incidence of Listeria monocytogenes
in cold smoked salmon in ready-to-eat product. They studied the antimicrobial
effect of edible coating of sodium lactate and sodium diacetate incorporated
into alginate coatings. The authors found that alginate-based coating containing
lactate and diacetate to control the growth of L. monocytogenes may increase food
safety of filleted and sliced smoked salmon [119].
Combination of citric acid dipping (5 g/L) and cassava starch coating (10
g/L), with and without glycerol (10 g/L) were found by Chiumarelli 2010 best
suited for edible coatings on fresh-cut mangoes stored at 5 degrees C during
15 days. Mango samples treated with citric acid and cassava starch coating
presented significant improvement of quality, however, glycerol in the coating
formulation was of no gain and even favoured microbial growth.
Plotto and colleagues 2010 found an antibrowning dip consisting of calcium
ascorbate, citric acid and N-acetyl-L-cysteine effective in keeping colour and
reduced firmness loss of fresh-cut mango slices stored at stored at 5 degrees C
for up to 20 days. Carrageenan or chitosan coating was of no quality gain of the
mango slices [121].
Kokoszka and colleagues 2010 tested edible films cast from heated (80 degrees
C for 30 min) aqueous solutions of whey protein isolate (100 g kg(-1) of
water) containing glycerol (50 g kg(-1)) as a plasticiser and rapeseed oil.
The authors report that small amounts of rapeseed oil increases the surface
hydrophobicity of films and decreases water vapour permeability, and welling of
whey protein isolate films is reduced. citeCiu 2010 romaine hearts
Chiu and Lai 2010 examined the antimicrobial activities of edible coatings
based on a 1.35% tapioca starch/ 0.15% decolorized hsian-tsao leaf gum and
0.225% glycerol matrix with various green tea extracts applied by spraying on
fruit-based salads, romaine hearts and pork slices. Pronounced reduction of
bacterial count and increased shelf life were noticed.
The authors stress the high migration of antimicrobial agents of the green tea
extract from the described coating to different types of foods.
Martins and colleagues 2010 found an considerable shelf life extension of
Ricotta cheese at 4 degrees C during 28 days using edible coatings made of
galactomannans from Gleditsia triacanthos and nisin. Listeria monocytogenes
contamination was significantly reduced.
The authors concluded that galactomannan-based edible coatings with incorporated
nisin, may increase safety of cheese products reducing Listeria monocytogenes
postcontamination during storage.
Edible composite coatings based on hydroxypropyl methylcellulose (HPMC), lipid
components (beeswax and shellac), and food preservatives with antifungal
properties were evaluated by Valencia-Chamorro 2009 on mandarins and oranges
to protect against citrus postharvest green moulds (Penicillium digitatum) and
blue molds (Penicillium italicum) during 7 days at 20 degrees C.
The authors tested various preservatives and found that the activity of
HPMC-lipid edible composite coatings containing sodium benzoate was twice that
of potassium sorbate based coating, and the antifungal action of the coatings was
fungistatic rather than fungicidal. Navarro-Tarazaga and colleagues 2008 investigated the effect of different fatty
acids on edible coatings based on hydroxypropyl methycellulose (HPMC)-beeswax.
Among the tested fatty acids the oleic acid coatings in concentrations of
1:0.5 and 1:0.2 presented the best results in reduction of weight and firmness
loss of mandarins compared to uncoated mandarins. However, the high
beeswax/oleic acid ratio of 1:0.5 coatings increased fruit internal CO2,
ethanol, and acetaldehyde contents of mandarins, indicating reduced flavour
compared to other coatings. The authors stress that testing of the effect of
coatings should measure permeance on the coated fruit.
Han and colleagues 2008 report that whey protein isolate coating of roasted
peanuts reduced the oxidation of peanut lipids. Antioxidants, such as ascorbic
palmitate and alpha-tocopherol, added to the coating layer, showed no further
protective effects of the fruits.
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