INDICES OF FOOD PLANT SANITATION
The type of building in which food products are manufactured and the several level of hygiene have a major influence on the microbiological quality of the product. A food manufacturer should build specification for the purpose of food production but in weak economy countries, this rarely happens and most times an existing building has to be modified if care is taken, even though a little extra money might be spent to adapt the building, the final outcome is that the unit is appropriate for food processing.
THE SITE
Often time, the location of the building is ignored but this is very important. The site should be on cleared ground, away from bush which is sources of insects, rodents and smells. It should have a good supply of potable water and electricity.
A good road access for bringing in raw materials and sending out the products is very essential. Other factors which are to be considered are;
1. access to the raw material supply
2. Nearness to markets
3. Labor must be available locally therefore, workers will not have a problem getting to work.
4. The site is situated in a clean area without dust, waste or stagnant water nearby.
THE BUILDING
The building should be clean and painted both internally and externally, surrounding the building short grass should be planted and maintained. Toilet facilities should be in a separate building preferable but if it is not possible there must be two closed doors between the toilet and the processing area to prevent insects and odors from entering.
The internal walls should be painted with water resistant paint or tiled from the bottom to about one meter above ground level. Food splashes can then be easily washed off from the walls and microbial build up on food debris will be prevented. The right angle of where the wall meets the floor should be curved to prevent trapping of dirt.
Cleaning is also easy when such edges are curve. Window hedges should slope so that they do not collect dust, dirt or old clothes that may be left by workers. The windows should be fitted with wire mesh to prevent insects and rodents from entering.
Gaps on the roof are also places where rodents can enter unto the building. The walls where power lines and pipes enter through are places where rats and other rodents can climb in. Food processing always requires a lot of water used for cleaning, washing etc,
floors must therefore be designed to drain effectively. To do this, it is best to slope all floors to a central drainage channel and the drain should be covered with a removable grating to allow for cleaning, drains are a favorite entering point for pests such as rats and cockroaches and the outlets must be fitted with a removable fine mesh. Electric power points should be at least 0 – 0.5 meters high from the floor to keep them dry from water and flood splash.
Fluorescent tubes are very good for lighting up food processing areas. However, normal bulbs should be used near machines that have fast moving parts. The building must have very good ventilation so that heat produced during food process operations such as steam can have exit. Extraction fans can also be installed in cases where the ventilation is poor.
The building must have a good supply of clean, potable water for cleaning equipments, cooling and mixing food ingredients. Most times, municipal water supply is often unreliable and food manufacturers must use other methods to overcome water supply problems.
LAYOUT
Most times especially in small factories poor layout is responsible for the poor quality of the food product. Most workers bump into each other and errors in food processing occur in this way. Two major principles to remember in the layout are;
1. There should be smooth flow of materials around the processing room from incoming materials to finished products.
2. Cross contamination should be avoided. It is very easy for sprays or splashes from unprocessed food to enter a container of product being filled after processing. This result in contamination and wasted food.
SANITATION AND HYGIENE
The building and equipment must be kept clean at all times. Workers must be trained to keep the equipment clean throughout the day and to remove wastes from the building as they accumulate. The manager must design a cleaning plan as an integral part of the work flow everyday and all staff should be trained to know their responsibilities.
Time must be given every day for effective cleaning after every food process operation. In dry processing, it is important that all dust is excluded and cleaned from old sacks or card boards etc. the objective is to prevent any areas where dust can collect or insects can breed. For wet processes, cleaning should involve the use of both detergents and sterilants.
Detergents remove food residues but do not kill micro-organisms. Sterilants such as chlorine can kill microorganism but do not remove residues. A good effective cleaning plan will first remove residues with a detergent and then treat the equipment with a sterilant.
Chlorinated water is needed for cleaning and washing raw materials and the required level of chlorine depends on the use. Water for cleaning requires a high level of chlorine up to 200 parts per million whereas water for washing raw ingredients contain about 0.5ppm to avoid giving the product a chlorine flavor.
Although, chlorine has a great advantage of killing a wide variety of microorganism it also has several disadvantages:
1. It can corrode equipment, especially aluminum equipment.
2. It can leave flavor taints if not well rinsed afterwards with potable water.
3. At high concentrations, it can damage the skin, the eyes or cause breathing problems.
PERSONAL HYGIENE
Personnel handling food are a potential source of contamination to foods. The risk depends on the type of food product. For instance, a food that is hot, filled, sealed and heat treated is at a lower risk than a food such as meat pie that became handled after it is cooked. Hygiene measures are as follows;
1. All food handlers should use clean uniforms.
2. All hair must be covered and hairy growth trimmed.
3. Finger nails should be trimmed. Hands must be sanitized with soap and water before every production section. Disposable towels are preferable for use in hand drying.
4. Hands must always be washed after using the toilet.
5. Smoking and spitting must never be done in processing rooms.
6. Food must not be eaten in the processing room (including product being produced)
7. Straws should be provided and area to change clothing.
8. All workers should be allowed to handle food.
9.Any worker suffering from diarrhea, cough, cold and skin infections should not under any circumstances be allowed to handle food.
Workers with boils or cuts that are infected especially on the hands should be removed from production. It is however important that workers do not get penalized for having an infection otherwise, they will tend to hide their problem such workers can be given other duties such as repairs, cleaning etc. Good manager ensures that staffs are aware of the risks that infections can pose to food that is being processed so that a worker does not feel unnecessarily punished for being ill
FOOD PRESERVATION
Food storage and preservation methods slow growth of microorganisms that produce spoilage and food borne diseases.
1. Cold: - One of the most crucial factors affecting microbial growth is temp. In general, a lower storage temp results in less microbial growth and slower spoilage. However, a number of psychrotolerent (cold-tolerant) micro organisms can grow, albeit- slowly, at refrigerator temp (3-5oC). Therefore, storage of perishable food products for long periods of time (More than several days) is possible only at temp below freezing. However because freezing and subsequent thawing alters the physical structure, freezing is not an acceptable preservation method for many fresh foods, but is widely used for the preservation of meats and many fruits and vegetables. Freezers providing a temp of -20oC are most commonly used. At -20oC, storage for weeks or months is possible, but microorganisms can still grow in pockets of liquid H2O trapped within the frozen mass for long-term storage, temps of -80oC (The temp of solid CO2 "Dry ice") are necessary. Maintained of such low temps is expensive and consequently is not used for routine food storage.
2. Pickling and acidity
Another factor affecting microbial growth in food is PH. Foods vary somewhat in Ph, but most are neutral or acidic. Microorganisms differ in their ability to grow under acidic condition, but conditions of Ph5 or less inhibit the growth of most spoilage organisms.
Therefore, weak acids are often used in food preservation in a process called pickling. Vinegar, a dilute acetic acid fermentation product of the acetic acid bacteria is usually added in the pickling process. Pickling methods usually mix the vinegar with large amounts of salt or sugar to decrease H2O availability & further inhibit microbial growth. Common pickled foods include peppers, meats, fish, fruits & cucumbers (Sweet, sour)
3. Drying and Dehydration
Water activity or aw, is a measure of the availability of water for use by micro organisms in metabolic processes. The aw of pure water is 1.00, the H2O molecules are loosely ordered and rearrange freely when solute is added, the aw is decreased. As water molecules re-order around the solute, the free rearrangement of the solute-bond water molecules becomes energetically unfavorable. The microbial cells must then complete with solute for the reduced amount of free H2O. In general, bacteria are poor competitors for the remaining free water, but fungi are good competitors. In practice this means that high Concentrations of solutes such as sugars or salts, which greatly reduce aw, typically inhibit bacteria growth for e.g most bacteria are inhibited by a conc of 7.5% Nacl (aw of 0.957) with the exception of some of the gram- +ve cocci such as Staphylococcus spp. On the other hand, molds compete well for free water under condition of low aw and often grow well in high sugar foods preserved by the addition of salt or sugar. Sugar is used mainly in fruits (Jams, jellies & preserves) salted products are primarily meats & fish. Some meat also undergoes smoking process. The preserved meat products vary widely in aw depending on how much salt is added & how much the meat has been dried. Microbial growth in foods can also be controlled by lowering the water content by drying. Drying is used to preserve highly perishable foods such as meat, fish, milk vegs, fruits. The least damaging physical method used to dry foods is the process of lyophilization (Freeze- drying) in which foods are frozen & water is then removed under vacuum. This method is very expensive, and is used mainly for specialized applications. Such as preparation of military rations that may need to be stored for long periods under adverse conditions.
Spray drying is the process of spraying, or atomizing, liquids such as milk in a heated atmosphere. The atomization produces small droplets, increasing the surface area-to-volume ratio of the liquid, promoting rapid drying without destroying the food. This technology is widely used in the production of powdered milk, certain concentrated liquid dairy product such as evaporated milk and concentrated food ingredients such as liquid flavorings.
4. HEATING
Heat is used to reduce the bacterial load of a food product or to actually sterilize it and is especially useful for the preservation of liquids and wet foods. Pasteurization does not sterilize liquids, but reduces the bacterial load of both spoilage organisms and pathogens and significantly extends the shelf life of the liquid.
Canning is a process in which food is sealed in a container such as a can or glass jar and then heated. In theory, canning should sterilize the food product, although this is not true 100% of the time. However, when properly sealed and heated, the average can of food should remain stable and unspoiled indefinitely at any temperature. The process used for commercial canning called retort canning, employs equipment similar to an autoclave to apply steam under pressure.
If live micro organisms remain in a can, growth of organisms can produce extensive amounts of gas and build pressure, resulting in bulges or, in severe cases, explosion. The environment inside a can is anoxic, and some of the anaerobic bacteria that grow in canned foods are toxin producers of the genus Clostridium. Food from a bulging can should never be eaten. On the other hand the lack of obvious gas production is not an absolute guarantee that canned food is safe to consume.
5. ASEPTIC FOOD PROCESSING
Several foods in the United States and many more in Asia and Europe are now prepared and packaged under aseptic conditions. Foods processed and packaged aseptically should be sterile and can be stored at room temp for months or longer without spoilage. Aseptic processing involves flash heating or cooking foods to sterility & then packaging them in aseptic containers, usually cardboard cartons lined with food and plastic. Liquid such as fruit juices & milk substitutes are often processed in this way. This developing technology increases product shelf life almost indefinitely and eliminates the need for refrigeration for many products. However, the equipment and processing plants necessary to achieve and maintain aseptic food processing and very expensive.
6. CHEMICAL PRESERVATION
Over 3,000 different compounds are used as food additives. These chemical additives are classified by the US Food and drug adminstation as 'Generally recognized as safe' (GRAS) and find wide application in the food industry for enhancing or preserving texture, color, freshness, or flavor. A small number of these compounds are used to control microbial growth in food.
Microbial inhibitors e.g sodium propionate & sodium benzoate have been used with no evidence of human toxicity.
Nitrites (a carcinogen precursor) ethylene oxide & propylene oxide (mutagens are more controversial food additives. The use of spoilage- retarding additives, however, significantly extends the useful shelf life of finished foods. Chemical food additives contribute significantly to an increase in quantity and in the perceived quality of available food items.
CHEMICAL FOOD PREERVATIVES
Chemical FOODS
Sodium or calcium propionate Bread
Sodium benzoate Carbonated beverages fruit, fruit juices, prickles, margarine
Sorbic acid Citrus products, cheese,
Prickles, salads
Sulfurdioxide, sulfites, Dried fruits & veg, wine
Bisulfites
Formaldehyde (From Meat, fish
Food-smoking process)
Ethylene and propyleneoxide Spices, dried fruit nuts
Sodium nitrite Smoked ham, bacom
7. IRRADIATION
Irradiation of food with ionizing irradiation is an effective method for reducing contamination by bacteria, fungi and even insects. Irradiated food products receive a controlled radiation dose. This dose varies considerably for each food category and purpose. in the United States, a consumer’s product information label must be affixed to foods that are irradiated.
Perishable food: fresh food generally of high water activity that has a very short shelf life due to potential for spoilage by growth of micro organisms.
Non perishable (stable) food: food of low water activity that has an extended shelf life and is resistant to spoilage by microorganisms.
Semi perishable food: food of intermediate water activity that has a limited shelf life due to potential for spoilage by growth of microorganism.
Prickling- the process of acidifying food to prevent microbial growth and spoilage.
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