Cleaning and sanitation are important operations in a food plant, necessary to minimize biological and other hazards that could lead to foodborne illnesses. These hazards come from several sources. Look back at your notes in the previous lesson to recall some of these sources. The cleaning and sanitation processes are two different steps in a plant hygiene plan. Cleaning is done to remove soil. Soil could be any material on food contact surfaces that should not be there such as food, grease, and chemicals. Once a thorough cleaning is done, sanitation is carried out to reduce bacteria levels to levels that are safe. Usually this is a 5 log reduction meaning 99.999% of the bacteria are killed. Another way of understanding this is:
- 1 log reduction = 10 times less bacteria
- 2 log reduction = 100 times less bacteria
- 3 log reduction = 1,000 times less bacteria
- 4 log reduction = 10,000 times less bacteria
- 5 log reduction = 100,000 times less bacteria
Assuming we start out with 1 million bacterial cells (an amount that could potentially fit on a pinhead), after a 5 log reduction we would still be left with 10. However this level would be deemed as “safe”.
Different classes of cleaners are used in the food industry to clean food contact and non-food contact surfaces. These are selected based on the type of soil to be removed. Cleaners include alkalis, phosphates, surfactants, chelating agents and acid. Many cleaners will be a combination of more than one classes in order to have multiple functions such as emulsifying, chelating, saponyfying, softening, rinsability, and peptizing (memorize definitions for these terms – see supplementary reading). In general, alkalis are used in removing fat and protein soils, while acids are used to remove mineral-based soils.
In selecting your cleaning compound, there are several considerations
- Assessment of your water quality. No operation can be truly cleaned and sanitized without a potable (drinkable) supply of water. Water should be free from particles that will end up reducing the effectiveness of your cleaning and sanitation process. Mineral content should also be low. High mineral water is referred to as hard water. Processors may install water softening systems to precipitate out minerals (mainly calcium and magnesium) as these salt not only hamper cleaning and sanitation but causes undesirable deposits and buildup in pipelines. Some cleaners will have chelating agents to bind minerals and prevent them from interfering with the cleaning process. Water supply should also be adequate with enough force to facilitate effective cleaning
- Determination of concentration, time and temperature needed to economically achieve desired cleaning. Generally your supplier will provide you with recommendations, but you will still need to verify in your plant based on sampling and swabs, that your desired hygiene status after cleaning is achieved
- Determine the appropriate method of cleaning. Cleaning methods may include soaking, manual scrubbing, clean-in-place (CIP), clean-out-of-place (COP), foaming and high-pressure cleaning. Where manual cleaning will be done, care must be taken to ensure that the cleaner will not cause harm or irritation to skin. Caustic and high-acid cleaners would be more suitable for CIP systems where the cleaner is pumped in an enclosed system without any physical contact with employees. If longer contact time is needed to dislodge soil, then foaming will offer some advantage.
- The nature of the surface to be cleaned. Various surfaces may be present in the food plant, including plastic (various grades), wood, aluminum, stainless steel and concrete. A question to ask is, what effect will the cleaner at the required concentration, have on the contact surface? Some surfaces may corrode, leading to discoloration or damaged surface where bacteria will hide and grow
Factors affecting cleaning quality include:
- The selected cleaner: should be based on factors discussed previously
- Temperature: higher temperatures will help to break bonds and adhesion to food surfaces
- Amount of agitation: more agitation will help to dislodge soil
- Time: the longer the treatment time, the greater the effect of soil removal
- Concentration: generally, increase in concentration will improve cleaning, however other variables such as time, temperature and agitation are more effective and hence better to change. Bear in mind also, the cost effect and possible hazardous effect of increasing concentration levels about what is required for desired cleaning
An example of a cleaning cycle is:
- Detergent application
- Acid wash
Sanitation may be accomplished using either heat (dry heat, hot water or steam) or chemicals. The use of chemicals is the most widely used approach. Common chemicals used are illustrated in the table below. In general, the mode of action for sanitizers include oxidation and damage of cell membranes and DNA. Like cleaning, several factors may determine the effectiveness of the sanitation process, such as sanitizer concentrations, pH, time, water hardness and cleanliness of the food surface prior to sanitation. Sanitizers may be applied by soaking, manual application, CIP, spraying and fogging.