438 ◾ Fundamental Food Microbiology
Many types of detergents are available, and they are selected based on the need. The effectiveness of a cleaning agent to remove soil from surfaces depends on several characteristics, such as
efficiency of emulsifying lipids, dissolving proteins, and solubilizing or suspending carbohydrates
and minerals. In addition, a detergent should be noncorrosive, safe, rinsed easily, and compatible,
when required, with other chemical agents. The detergents frequently used in food-processing
facilities are synthetic, which can be anionic, cationic, or nonionic. Among these, anionic detergents are used with higher frequency. Examples of anionic detergents include sodium lauryl sulfate
and different alkyl benzene sulfonates and alkyl sulfonates. Each molecule has a hydrophobic or
lipophilic (nonpolar) segment and a hydrophilic or lipophobic (polar) segment. The ability of a
detergent to remove dirt from a surface is attributed to the hydrophobic segment of a molecule.
They dissolve the lipid materials of the soil on the surface by forming micelles with the polar segments protruding outside in the water. The concentration of a detergent at which micelle formation starts is called the critical micelle concentration (CMC), which varies with the detergent.
The concentration of a detergent is used above its CMC level. Generally, this is approximately
800–900 ppm but could be 1000–3000 ppm if skin contact does not occur (as in the clean-inplace or CIP method) or where heavy-duty cleaning is required.
The frequency of cleaning depends on the products being processed and the commitment of
the management to good sanitation. From a microbiological standpoint, prior microbiological
evaluation of a product can give an indication about the frequency of cleaning necessary in a
particular facility. Cleaning of the equipment is done either after disassembling the equipment
or by the CIP system. Because of its efficiency and lower cost, CIP cleaning has become popular.
The system uses detergent solutions at a high pressure. Because microorganisms can grow in some
detergent solutions, they preferably should be prepared fresh (not exceeding 48 hours). 1
Sanitation of Food-Processing Equipment
Efficient cleaning can remove some microorganisms along with the soil from the food-contact surfaces, but it cannot ensure complete removal of pathogens. To achieve this goal, food-contact surfaces are subjected to sanitation after cleaning. The methods should effectively destroy pathogenic
microorganisms as well as reduce total microbial load. Several physical and chemical methods are
used for sanitation of food-processing equipment.
Physical agents used for sanitation of food-processing equipment include hot water, steam, hot
air, and UV irradiation. UV irradiation is used to disinfect surfaces and is discussed in Chapter
39. Hot water and steam, although less costly and efficient for destroying vegetative cells, viruses,
and spores (especially steam), can be used only in a limited way.
Chemical sanitizers are used more frequently than physical sanitizers. Several groups of sanitizers are approved for use in food-processing plants. They vary greatly in their antimicrobial
efficiency. Some of the desirable characteristics used in selecting a chemical sanitizer are effectiveness for a specific need, nontoxicity, noncorrosiveness, no effect on food quality, ease of use and
rinse, stability, and cost effectiveness. Important factors for antimicrobial efficiency are exposure
time, temperature, concentrations used, pH, microbial load and type, microbial attachment to
surface, formation of biofilm, and water hardness. Microbial attachment has been discussed separately (see Chapter 7). The mechanisms of antimicrobial action and the advantages and disadvantages of some of the sanitizers used in food-processing plants are briefly discussed here. Some
sanitizers, designated as detergent sanitizers, can both clean and sanitize. They can be used in a
single operation instead of first using detergent to remove the soil and then using sanitizers to
control microorganisms. They are also discussed here. 4,6
Many types of detergents are available, and they are selected based on the need. The effectiveness of a cleaning agent to remove soil from surfaces depends on several characteristics, such as
efficiency of emulsifying lipids, dissolving proteins, and solubilizing or suspending carbohydrates
and minerals. In addition, a detergent should be noncorrosive, safe, rinsed easily, and compatible,
when required, with other chemical agents. The detergents frequently used in food-processing
facilities are synthetic, which can be anionic, cationic, or nonionic. Among these, anionic detergents are used with higher frequency. Examples of anionic detergents include sodium lauryl sulfate
and different alkyl benzene sulfonates and alkyl sulfonates. Each molecule has a hydrophobic or
lipophilic (nonpolar) segment and a hydrophilic or lipophobic (polar) segment. The ability of a
detergent to remove dirt from a surface is attributed to the hydrophobic segment of a molecule.
They dissolve the lipid materials of the soil on the surface by forming micelles with the polar segments protruding outside in the water. The concentration of a detergent at which micelle formation starts is called the critical micelle concentration (CMC), which varies with the detergent.
The concentration of a detergent is used above its CMC level. Generally, this is approximately
800–900 ppm but could be 1000–3000 ppm if skin contact does not occur (as in the clean-inplace or CIP method) or where heavy-duty cleaning is required.
The frequency of cleaning depends on the products being processed and the commitment of
the management to good sanitation. From a microbiological standpoint, prior microbiological
evaluation of a product can give an indication about the frequency of cleaning necessary in a
particular facility. Cleaning of the equipment is done either after disassembling the equipment
or by the CIP system. Because of its efficiency and lower cost, CIP cleaning has become popular.
The system uses detergent solutions at a high pressure. Because microorganisms can grow in some
detergent solutions, they preferably should be prepared fresh (not exceeding 48 hours). 1
Sanitation of Food-Processing Equipment
Efficient cleaning can remove some microorganisms along with the soil from the food-contact surfaces, but it cannot ensure complete removal of pathogens. To achieve this goal, food-contact surfaces are subjected to sanitation after cleaning. The methods should effectively destroy pathogenic
microorganisms as well as reduce total microbial load. Several physical and chemical methods are
used for sanitation of food-processing equipment.
Physical agents used for sanitation of food-processing equipment include hot water, steam, hot
air, and UV irradiation. UV irradiation is used to disinfect surfaces and is discussed in Chapter
39. Hot water and steam, although less costly and efficient for destroying vegetative cells, viruses,
and spores (especially steam), can be used only in a limited way.
Chemical sanitizers are used more frequently than physical sanitizers. Several groups of sanitizers are approved for use in food-processing plants. They vary greatly in their antimicrobial
efficiency. Some of the desirable characteristics used in selecting a chemical sanitizer are effectiveness for a specific need, nontoxicity, noncorrosiveness, no effect on food quality, ease of use and
rinse, stability, and cost effectiveness. Important factors for antimicrobial efficiency are exposure
time, temperature, concentrations used, pH, microbial load and type, microbial attachment to
surface, formation of biofilm, and water hardness. Microbial attachment has been discussed separately (see Chapter 7). The mechanisms of antimicrobial action and the advantages and disadvantages of some of the sanitizers used in food-processing plants are briefly discussed here. Some
sanitizers, designated as detergent sanitizers, can both clean and sanitize. They can be used in a
single operation instead of first using detergent to remove the soil and then using sanitizers to
control microorganisms. They are also discussed here. 4,6