Subsections

Hygienemonitoring

To achieve safety on regard of disease agents and to secure shelf-life are the central concern of hygiene of every food processing.
Continuous training of the people which are engaged with handling and processing of food is vital importance. To guarantee safe foods it is necessary to control the raw material which is being used. Check the processing, the packaging, the end product and last but not least necessary to keep samples of all charges until expiring date.
Example of wood as bacterial contamination is demonstrated by a splinter of wood cultivated on plate count agar: $\includegraphics[width=300bp,height=230bp]{library/p1250024.ps}$ Hygiene monitoring tries to avoid the contamination caused by raw materials, not sterile packagings, the influence of the environment and wrong behavior of the staff. Hygienemonitoring is a part of the HACCP Program which was introduced in the European community by law
The hygiene may be supervised by :

Traditional methods such as contact cultures of surfaces of utensils and parts of machines,and culture of swabs of places to be difficultly reached,final results taking 2 to 3 days.
quick methods based upon ATP-Bioluminescence final results taking about 2 minutes

ATP-Bioluminescence

ATP-Bioluminescence is used to supervise cleaning in food industries and other industries where perfect cleaning is necessary.
ATP finds also increased use in special methods of detection and counting of bacteria.

Hygienemanagement in food industry

In the production of food quick methods are important to check the quality of cleaning.
During the cleaning of utensils and machines it is important to remove from the surfaces as much organic material as possible

to insure a later disinfection and to avoid protein failure and
to withdraw organic material for further growth of bacteria.

The ATP-luminescence measures the ATP (Adenosine tri phosphate) from animal and from vegetable cells as well as living or dead bacteria. It shows in this manner how much impurities have been left after cleaning.

Principle of the ATP-bioluminescence-method:
The ATP taken up with a swab from approximately 100 cm

of the surface to be tested is put together with a luciferin/luciferase system of commercially available kits. There is light emitted which is proportional to the amount of ATP being present. This light is measured with a luminometer as "Relative Light Units RLU" .
The light being emitted during this method is proportional to the amount of ATP being present on the surface to be examined.
In order to achieve a better supervision of the hygiene it is advisable to use both system: The ATP luminescence method showing how much residues are left after cleaning, and the normal method of contact cultures telling what kind of bacteria are present,
As the ATP-method gives the total amount of organic material left, it is necessary to determine for every place how much residues are still being considered as "good", and "bad".
To determine the maximum RLU being accepted for these two points proceed as following:
Measure for about 1 week the RLU of all relevant places of the production line and list the results for each place and note as:

Good cleaning: Sum total of RLU measured during one week divided by the number measures for each place.
Bad cleaning: 2 times the "Good Cleaning" point.

In order to determine the standard of hygiene which can be obtained during normal production proceed as follow:
Determine the RLU after "normal" cleaning.
Continue the cleaning by hand using different detergents and determine the RLU after "rigorous cleaning". This is considered as being the best achievable cleaning.
The best reference data are those values of "normal cleaning"which are as close as possible to the values of "rigorous cleaning".

After one to two month repeat the determination of the reference points "good" and "bad". It is very likely that these points will be reduced because cleaning is growing better as a result of the continuous supervision.

The checks may be "horizontal" being made on the same specific critical places of all machines.
It is good to change from time to time to "vertical" checks from isolated machines checking all their parts.

Understanding cleaning of food process plants

[]
Liu and colleagues assessed the removal of food fouling deposits during the cleaning of process plants. According to the authors deposits form by adhesion to the surface and cohesion between elements of the deposit. Cleaning can result from either or both adhesive and cohesive failure.

The authors measured the adhesive/cohesive strength of deposits in terms of the work required to remove them from the surface, using a range of coated surfaces They found that tomato paste, bread dough and egg albumin deposits have a lower adhesive than cohesive strength, whilst others (whey protein) have a lower cohesive than adhesive strength.

The researchers present a simple model to analyse the results in terms of the work required to remove the deposit per unit surface area and volume.

DNA based pathogen detection system from Lumora [185]
The food safety diagnostics company Lumora developes a detection system which identifies and measures food borne pathogens such as Salmonella, E. coli O157 and Listeria by means of a version of a luciferase gene. Specific bacteria in contact with this gene emit light which is identified by a sensor. In this way the precise amount of contamination can be determined within hours. The system will be available soon.

The system may also detect small quantities of genetic modified material in foods and may enhance the traceability of ingredients.

Hygienic training of the staff

The Hygiene rule 93/43/EWG demands also for a training of the staff. To train your staff show the bacterial count made on Plate count Agar Base. Bad cleaning and disinfection resulting in food spoilage : innumerous bacteria on the surface of a table. Good cleaning and disinfection gives low bacterial count of the surface of the table. On Plate Count Agar Base there are no colonies grown. A good shelf life of food is the result.

Cleaning with CO2 in food industry

[186] The main concern of cleaning in food industry is:

Remove the coatings of rest of product and dirt.
Reduce the number of bacteria an the surface of machines and utensils, preparing the field for a following disinfection.

Cleaning must be made very carefully. It is expensive, produces great amount of waste-water, chlorine and other disinfectants.
Cleaning with pellets of carbon dioxide can be an alternative to conventional cleaning methods. CO2 pellets are mixed with an air jet and directed against the surface to be cleaned under high pressure at about 20 bar.
The reduction of the surface temperature due to sublimation of the carbon dioxide hardens the layers to be removed and cracks are formed. The undesired material starts to peel off. An abrasive action takes place.
The cracks formed on the surface of product layers due to very low temperatures allows carbon dioxide pellets to get under and between the undesired material. As the pellets sublimate they enlarge their volume about 700 times removing thus foreign material like organic rest, dirt and bacteria.
The DIL (Deutsches Institut fr Lebensmitteltechnik) has tested this technique with good results in cleaning and reduction of the number of surface bacteria.

Cleaning and disinfection, Standard method

(According Codex Alimentarius) Good hygiene includes the following steps

Cleaning of building, of tools and equipment and the transportation system. Important is the complete removal of food rests and garbage from the rooms where production takes place.
Disinfection using an appropriate disinfectant. Sometimes the cleaning step is combined with the disinfection. This is efficient because organic material inhibits the disinfection agents or built a protective layer around microorganism.
The cleaning and disinfection method before being included in the daily work should be discussed and authorized by:
Veterinary authorities in charge
Production management
Engineering management and
Supplier of cleaning and disinfection agents.
The cleaning and disinfection method should be written and be available to the personal engaged in the daily work and to the production management.
Cleaning instructions should include the handling of cleaning equipment such as disinfection of scrub brushes an buckets.
The production management should continuously supervise cleaning and disinfection in order to make sure the work is being done according instructions observing the prescribed intervals.
All persons engaged in cleaning and disinfection should be instructed regarding the caution in handling chemicals such as:
Alkaline solutions should not be put together with acid solutions.
Hypochlorite solutions should not be put together with acid solutions because chlorine gas can be generated.
All chemical containers must be labeled so that everyone can know its content. They must be kept separate from food and packing material.
Handling strong concentrated chemicals the use of gloves, safety goggles and protective clothes are necessary.
Good cleaning and disinfection results: a low bacterial count is found at the surface of the equipment:
$\includegraphics[width=300bp, height=200bp]{library/p9090042.ps}$
Bad cleaning and disinfection results: a high bacterial count is found at the surface of the equipment:
$\includegraphics[width=300bp, height=200bp]{library/p9100049.ps}$

Cleaning methods

Cleaning methods should remove the main part of food and other materials from the surfaces with could or hot water.
Cleaning agents should remove strongly adherent rests.
Clear water should wash the cleaning agents away.
Abrasive substances or acid solutions should not interfere with surface.
Cleaning can be made by

hand using brushes,
Cleaning in place (CIP method): This method is being used in large scale to clean pipe systems, tanks and machines without disassemble them.The system must be appropriated for CIP cleaning.
The Flow of water and cleaning solutions should be over 1,5 meter per second having flushing character.
Flushing with low pressure using much water: This method uses much water under 6,8 bar (100 psi) pressure and great amount with chemicals.
Flushing with high pressure and little water:
High pressure up to 68 bar (1.000 psi) is used.
Foam cleaning:
The cleaning agents are integrated in the foam sticking on the surfaces to be cleaned for about 15 to 20 minutes. They are then washed away. Openly accessible surfaces can easily be cleaned and disinfected with foaming and disinfecting cycles.
Wash machines:
Small parts, buckets an other utensils can be washed and disinfected
Cleaning agents There may be necessary to use heat in order to get good cleaning results.
Sometimes cold solutions are sufficient.
Mineral salts may deposit scale. Small amount of scale can be detected with ultraviolet light.

After all cleaning agents have been washed away disinfection can follow.

Disinfection

Disinfection are the methods to reduce the number of bacteria living on the surfaces. Disinfection can be made using:

Heat

The most common way of disinfection is to rise the temperature of the surfaces to a minimum of 70 $^{0}$ C (160 $^{0}$ F).
The surfaces to be disinfected should be clean having no rests of product left, otherwise protein would coagulate building insoluble layers.

Disinfection with hot water

IndexHot water as disinfectant This method is widely used. Machines and parts to be disinfected are immersed in hot water at 80 $^{0}$ C (176 $^{0}$ F) for at least two minutes.
Water to rinse off disinfectants in mechanical dish washers should have this temperature.

Steam as disinfectant

Steam can be used to disinfect tanks, pipes and other parts which are not easily reached.
Steam must be applied long enough to heat up the surfaces to temperatures which can kill bacteria. Steam can be unsuitable for machines and systems containing plastic materials or gaskets which are destroyed by high temperatures. Steam kills bacteria even when they are located behind gaskets. Chemical disinfectants does have the same property as seen from the disinfection using steam.
Steam disinfection can give origin to condensing water which can collect in in pipes and tank drain giving chance to bacteria to grow. Therefore it is important to repeat steam disinfection after a standstill for more then one day.

Chemical disinfection

Chemical disinfectants are reduced in their activity in presence of dirt and other residues of food. Disinfectants are useless when the amount of residues are to high. Therefore disinfection should always be preceded by a cleaning procedure. High temperatures increases the activity of chemical disinfectants.There is however a limit of temperature for every disinfectant. The technical informations of the suppliers of the chemical must be observed. Iodophores give iodine free which can corrode metal, so as chlorine producing corrosion coming from hot hypochlorite solution. All chemical disinfectants need time to kill bacteria. This time differs from one disinfectant to another according to the technical informations.
The concentration of the disinfection solutions must be made according to the informations of the supplier. They should not be mixed with cleaning agents or other disinfectants because of loss of activity. The most important chemical disinfectants are:

Chlorine and their compounds

Chlorine and products on basis of Chlorine such as hypochlorite-compounds are the best chemical disinfectants.
Commercial products have 100 to 120 gram chlorine per liter being active against a great number of bacteria. They have low prices compared with other chemical disinfectants.
Working solutions should have 200 to 250 mg of active chlorine/Kg.
Chlorine disinfection is being substituted by other disinfectants because of environment. Chlorine reacts with organic residues forming AOX compounds. . Chlorine produces corrosions and turns inactive in presence of residues of food and dirt.

Whey permeate as alternative to chlorine solutions for preserving fresh-cut vegetables

[187] A chlorine 120 ppm (pH 8) solution is widely used in the washing treatmen as sanitizing agent prolonging the shelf-life of fresh-cut fruits and vegetables. The use of chlorine in food processing plants is being reduced due to the possible formation of carcinogenic chlorinated compounds in water.
In a study leaded by Anabelen Martin-Diana whey permeate solution was used as antimicrobial agent to control total bacteria counts during washing step of fresh cut vegetables as an alternative to chlorine.
The whey permeate from Glanbia, Ireland was used in the following solutions:

0.5% (pH 3.84)
1.5% (pH 3.53)
3% (pH 3.45)

Fresh-cut lettuce and carrot packages stored at 4 $^{0}$ C were monitored over 10 days. Whey permeate at 3% resulted in equivalent or better microbial load reduction than chlorine. Although lower concentration of whey permeate produced minor initial reduction, microbial counts at the end of the storage of 10 days at 10 $^{0}$ were below the recommended levels (10 $^{8}$ CFU/g) for safety of fresh-cut vegetables.

According to the researchers the anti-microbial activity is most likely due to the pH of the wash solutions, or the presence of bio-active peptides.

These results suggest that whey permeate could be a promising alternative to chlorine for sanitizing fresh-cut vegetables.

Iodophore

Iodophores may be used in combination with acid cleaning agents. They need a short time of contact with the surfaces, killing a broad spectrum of bacteria.
Working solutions should have a concentration of 25 to 50 milligram/liter of active iodine using a pH < 4. iodophores are inactivated in presence of food residues and dirt. They have yellow color when active iodine is still present. Loss of color indicates the loss of activity.
They can be corrosive, being necessary to flush away the iodophores with clean water.

Ammonium quarternairy-compounds

Theses substance have good cleaning activity and have low corrosive activity. They are not toxic. Their taste is bitter. These compounds tend to settle on the surfaces, therefore it is important to rinse with clear water carefully after disinfection. They should be used in 200 to 1200 milligrams per liter solution. Using hard water high concentrations must be used. They should not be used together with soaps and anionic cleaning agents. Their activity against Gram negative bacteria are smaller as found by chlorine.

Surfactants (amphotheric surface active substances)

Surfactants are old disinfection agents being made out of active agents with cleaning and bactericide activity. They are low toxic, tasteless and have little corrosive activity.Organic rests inactivate surfactants.

Strong acids and basic agents

Strong acids and basic reacting agents have cleaning and disinfectant activities.

They can easily contaminate food. They should be handled with great care.

Control of the activity of cleaning

The control of the cleaning and disinfection activity of the system being used should be made using bacteriological methods described above.

Improving CIP technology

[188] Efforts of reduction of environmentally harmful and cost-intensive resources for CIP-cleaning installations include per acetic acid sensor systems, chlorine-dioxide disinfection.

Chlorine-dioxide disinfecting procedures [188] Chlorine-dioxide disinfecting procedures are designed for drinking water disinfection, removal of odour and taste substances (phenols, algae, algae decomposition products), and reduction of organo-chlorine formations (AOX)

Chlorine-dioxide is used for the purification of water in CIP-installations, usage water, cooling water and waste water, in fillers, process water, and in washing maschines.

Per acetic acid [188]
Per acetic acid is being used in CIP processes for disinfection. Its spectrum includes bacteria, yeasts, algae and viruses, breaking down to oxygen and traces of acetic acid. No rinsing of the plant is therefore necessary.

Origin of Contamination of food with pathogen bacteria

is originated by:

Contaminated raw material e.g. water, meat, cereals.
Handling e.g.unclean devices, bacteria bearing surfaces of machines etc.
Environment e.g. dust, unclean rooms, polluted air from air conditioning systems.
Personal e.g.sick persons handling food. To avoid contamination wash hands before starting work, after visiting toilet and before starting with a new work. Disinfection solution should be used after washing. There are lots of bacteria on fingers as shown by fingerprints on nutrient media: $\includegraphics[width=300bp,height=230bp]{library/p1250022.ps}$

Clean room technology

Clean room technology is being used in the microelectronic, micro optics, in hospitals, pharmaceutical industry, cosmetic industry, research laboratories and many other branches.
To guarantee a clean environment of a room the air must be filtered. Today air filters are available which can filter particles 0,12 micro m. Clean air, correct temperature humidity and pressurization of the room are fundamental parts of clean room technology.
The outlets of the air system should be located over the places where handling takes place, such as:
Cutting machines,
Can openers,
Mixer,
Bowl-choppers.
In this way processing heat,from staff contaminated air and microorganism which may multiply in standing air or humidity are driven away by the sterile air flow of the air conditioning system. To avoid not filtered air to get into the clean room through doors and other outlets it important to create a pressure high enough to overcome atmospheric variations. Laminar airflow is often used to achieve safety at doors.
The airflow should be always against the staff and never from the staff to the product which is being handled as contamination of living beings is unavoidable. This type of clean room is called island solution and is much cheaper as what is being described for clean rooms in VDI- guideline 2083 or US-FS 209 E for the RR-class demanding the filtration of particles down to 0,5micro m. In food processing the aim is to avoid bacterial contamination. As these microorganisms are generally linked to particles between 0,12 and 100 micro m. The filter should be from the class 14 and better.
One important factor of a product contamination is the staff which produces particles down to 0,5 micro m.
Moist of the contamination results from breathing, talking, coughing and movements.
Microorganism isolated from the skin,nose, mouth and bowl are Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Enterobacteriaceae like Salmonella and Shigella. People with clinical signs like boils and suppurating wounds, diarrhea and strong cough should report this to the management and be released from working with unpacked food or send home for medication.
The personal which works in a clean room must b e dressed with special headdress to avoid bacteria from hairs to contaminate air. An overall should cover all the part of the body, shoes should be changed before entering the clean room. There should be a flood gate entering the clean room.in front of this flood gate there should be a device to clean shoes, gloves. This outfit should be changed daily.
In the clean room personal belongings are not allowed. Eat and drink in the clean room is not allowed. Private food and drink should not be taken into the clean room.
A high motivation of the staff is necessary. This can only be achieved when the environment of the clean room has been put in accordance to hygienic rules like the disposal of trash, tiled walls and floor, machines and other devices made of stainless steel without rusty parts.

Corrigendum to Regulation (EC) No 853/2004 of the European Parliament
EU regulation No 853/2004, part of the package of hygiene laws that came into effect on 1 January, provides a legal basis to permit the use of a substance other than potable water to remove surface contamination from products of animal origin. Previously, such a legal basis did not exist in the bloc's legislation for red meat and for poultry meat. [189]

Microorganisms as indicators of on-farm hygiene practices [194]
On-farm hygiene related to the cow's udder and teats, the milking equipment or the storage tank influence quality and quantity of bacteria in freshmilk. Bacterial mastitis can also lead to poor raw milk quality.

Total viable counts (TVCs) are do not always giving a true measure of on-farm hygiene during milking. Hutchison and colleagues compared total viable counts, Escherichia coli, coliforms, Bacillus spp., Bifidobacteria spp., and Pseudomonas spp. with results of dairy farm hygiene audits. They investigated the possible reasons for the low correlations between on-farm hygiene and bacterial indicator counts in raw milk.

The authors concluded that despite some problems, total viable count was best suited as indicator of on-farm hygiene. There were no other marker bacteria with higher correlation with audits.

Somatic cell count reflect any possible mastitis in the herd.

Health rules for milk in Europe [195] The Council Directive 92/46/EEC of 16 June 1992 lays down the health rules for the production and placing on the market of raw milk, heat-treated milk and milk-based products
RABIT (Rapid Automated Bacterial Impedance Technique) [196] [197]
Impedance microbiology is a rapid method for both quantitative and qualitative studies with bacteria, yeasts and moulds. Unlike the standard plate methods which only measure microbial activity at a single point in time, RABIT monitors real time activity and thereby produces two significant benefits. Results are determined in a significantly shorter time frame compared to conventional microbiology.

Impedance can be simply defined as the resistance to flow of an alternating current as it passes through a conducting material. When two metal electrodes are immersed in a conductive medium the test system behaves as a resistor and capacitor in series.
Microbial metabolism usually results in an increase in both conductance and capacitance causing a decrease in impedance and a consequent increase in admittance, it is the admittance which is plotted against time by the RABIT system.

Bacteria metabolise the nutrients of the media, producing a change of conductivity and resistance. When a bacteria arrive a concentration of log 5/ml it will cause a change of these parameters.A large initial population of bacteria will make the time to make this change will be shorter than a food with less concentration of bacteria. In the same food system, the number of the initial population of the food can be estimated by the detection time.