36 ◾ Fundamental Food Microbiology
a sewage-treatment plant), different types of bacteria, including pathogens and viruses (including
bacteriophages), can be transmitted via the air.
Microbial contamination of food from the air can be reduced by removing the potential
sources, controlling dust particles in the air (using filtered air), using positive air pressure, reducing humidity levels, and installing UV light.
Soil
Soil, especially the type used to grow agricultural produce and raise animals and birds, contains
several varieties of microorganisms. Because microorganisms can multiply in soil, their numbers
can be very high (billions/g). Many types of molds, yeasts, and bacterial genera (e.g., Enterobacter,
Pseudomonas, Proteus, Micrococcus, Enterococcus, Bacillus, and Clostridium) can enter foods from
the soil. Soil contaminated with fecal materials can be the source of enteric pathogenic bacteria
and viruses in food. Sediments in which fish and marine foods are harvested can also be a source
of microorganisms, including pathogens, in those foods. Different types of parasites can also get
in food from soil. Removal of soil (and sediments) by washing and avoiding soil contamination
can reduce microorganisms in foods from this source.
Sewage and Manure
Sewage, especially when used as fertilizer in crops, can contaminate food with microorganisms,
the most significant of which are different enteropathogenic bacteria and viruses. This can be a
major concern with organically grown food and many imported fruits and vegetables, in which
untreated sewage and manure might be used as fertilizer. Pathogenic parasites can also get into
food from sewage.
To reduce incidence of microbial contamination of foods from sewage, it is better not to use
sewage as fertilizer. If used, it should be efficiently treated to kill the pathogens. Also, effective
washing of foods following harvesting is important.
Water
Water is considered “environmental commons” and essential in the entire food production chain
and can spread disease easily. Water is used to produce, process, and, under certain conditions,
store foods. It is used for irrigation of crops, drinking by food animals and birds, raising fishery
and marine products, washing foods, processing (pasteurization, canning, and cooling of heated
foods) and storage of foods (e.g., fish on ice), washing and sanitation of equipment, and processing
and transportation facilities. Water is also used as an ingredient in many processed foods. Thus,
water quality can greatly influence the microbial quality of foods. Contamination of foods with
pathogenic bacteria, viruses, and parasites from water has been recorded.
Wastewater can be recycled for irrigation. However, chlorine-treated potable water (drinking
water) should be used in processing, washing, sanitation, and as an ingredient. Although potable water does not contain coliforms and pathogens (mainly enteric types), it can contain other
bacteria capable of causing food spoilage, such as Pseudomonas, Alcaligenes, and Flavobacterium.
Improperly treated water can contain pathogenic and spoilage microorganisms. To overcome the
problems, many food processors use water, especially as an ingredient, that has a higher microbial
quality than that of potable water.
a sewage-treatment plant), different types of bacteria, including pathogens and viruses (including
bacteriophages), can be transmitted via the air.
Microbial contamination of food from the air can be reduced by removing the potential
sources, controlling dust particles in the air (using filtered air), using positive air pressure, reducing humidity levels, and installing UV light.
Soil
Soil, especially the type used to grow agricultural produce and raise animals and birds, contains
several varieties of microorganisms. Because microorganisms can multiply in soil, their numbers
can be very high (billions/g). Many types of molds, yeasts, and bacterial genera (e.g., Enterobacter,
Pseudomonas, Proteus, Micrococcus, Enterococcus, Bacillus, and Clostridium) can enter foods from
the soil. Soil contaminated with fecal materials can be the source of enteric pathogenic bacteria
and viruses in food. Sediments in which fish and marine foods are harvested can also be a source
of microorganisms, including pathogens, in those foods. Different types of parasites can also get
in food from soil. Removal of soil (and sediments) by washing and avoiding soil contamination
can reduce microorganisms in foods from this source.
Sewage and Manure
Sewage, especially when used as fertilizer in crops, can contaminate food with microorganisms,
the most significant of which are different enteropathogenic bacteria and viruses. This can be a
major concern with organically grown food and many imported fruits and vegetables, in which
untreated sewage and manure might be used as fertilizer. Pathogenic parasites can also get into
food from sewage.
To reduce incidence of microbial contamination of foods from sewage, it is better not to use
sewage as fertilizer. If used, it should be efficiently treated to kill the pathogens. Also, effective
washing of foods following harvesting is important.
Water
Water is considered “environmental commons” and essential in the entire food production chain
and can spread disease easily. Water is used to produce, process, and, under certain conditions,
store foods. It is used for irrigation of crops, drinking by food animals and birds, raising fishery
and marine products, washing foods, processing (pasteurization, canning, and cooling of heated
foods) and storage of foods (e.g., fish on ice), washing and sanitation of equipment, and processing
and transportation facilities. Water is also used as an ingredient in many processed foods. Thus,
water quality can greatly influence the microbial quality of foods. Contamination of foods with
pathogenic bacteria, viruses, and parasites from water has been recorded.
Wastewater can be recycled for irrigation. However, chlorine-treated potable water (drinking
water) should be used in processing, washing, sanitation, and as an ingredient. Although potable water does not contain coliforms and pathogens (mainly enteric types), it can contain other
bacteria capable of causing food spoilage, such as Pseudomonas, Alcaligenes, and Flavobacterium.
Improperly treated water can contain pathogenic and spoilage microorganisms. To overcome the
problems, many food processors use water, especially as an ingredient, that has a higher microbial
quality than that of potable water.