Sources of Microorganisms in Foods ◾ 37
Humans
Between production and consumption, foods come in contact with different people handling the
foods. They include not only people working on farms and in food-processing plants, but also
those handling foods at restaurants, catering services, retail stores, and at home. Human carriers
have been the source of pathogenic microorganisms in foods that later caused foodborne diseases,
especially with ready-to-eat foods. Improperly cleaned hands, lack of aesthetic sense and personal
hygiene, and dirty clothes and hair can be major sources of microbial contamination in foods. The
presence of minor cuts and infection on the hands and face and mild generalized diseases (e.g.,
flu, strep throat, or hepatitis A in an early stage) can amplify the situation. In addition to spoilage
bacteria, pathogens, such as Staphylococcus aureus, Salmonella serovars, Shigella spp., pathogenic
Esc. coli, norovirus, and hepatitis A, can be introduced into foods from human sources sometimes
through fecal-oral contamination.
Proper training of personnel in personal hygiene, regular checking of health, and maintaining
efficient sanitary and aesthetic standards are necessary to reduce contamination from this source.
Food Ingredients
In prepared or fabricated foods, many ingredients or additives are included in different quantities.
Many of these ingredients can be the source of both spoilage and pathogenic microorganisms. Various
spices generally have very high populations of mold and bacterial spores. Starch, sugar, and flour
might have spores of thermophilic bacteria. Pathogens have been isolated from dried coconut, eggs,
nuts, flours, and chocolate, and many of these ingredients were responsible for foodborne outbreaks.
The ingredients should be produced under sanitary conditions and given antimicrobial treatments. In addition, setting up acceptable microbial specifications for the ingredients will be
important in reducing microorganisms in food from this source.
Equipment
A wide variety of equipment is used in harvesting, transporting, slaughtering, processing, and
storing foods. Many types of microorganisms from air, raw foods, water, and personnel can get
into the equipment and contaminate foods. Depending on the environment (moisture, nutrients,
and temperature) and time, microorganisms can multiply and, even from a low initial population,
reach a high level and contaminate large volumes of foods. Also, when processing equipment is
used continuously for a long period of time, microorganisms initially present can multiply and act
as a continuous source of contamination in the product produced subsequently. In some equipment, small parts, inaccessible sections, and certain materials might not be efficiently cleaned and
sanitized. These dead spots can serve as sources of both pathogenic and spoilage microorganisms
in food. Small equipment, such as cutting boards, knives, spoons, and similar articles, because
of improper cleaning, can be sources of cross contamination. Salmonella, Listeria, Escherichia,
Enterococcus, Micrococcus, Pseudomonas, Lactobacillus, Leuconostoc, Clostridium, Bacillus spp., and
yeasts and molds can get into food from equipment (see Chapter 21).
Proper cleaning and sanitation of equipment at prescribed intervals are important to reduce
microbial levels in food. In addition, developing means to prevent or reduce contamination from
air, water, personnel, and insects is important. Finally, in designing the equipment, potential
microbiological problems need to be considered.
Humans
Between production and consumption, foods come in contact with different people handling the
foods. They include not only people working on farms and in food-processing plants, but also
those handling foods at restaurants, catering services, retail stores, and at home. Human carriers
have been the source of pathogenic microorganisms in foods that later caused foodborne diseases,
especially with ready-to-eat foods. Improperly cleaned hands, lack of aesthetic sense and personal
hygiene, and dirty clothes and hair can be major sources of microbial contamination in foods. The
presence of minor cuts and infection on the hands and face and mild generalized diseases (e.g.,
flu, strep throat, or hepatitis A in an early stage) can amplify the situation. In addition to spoilage
bacteria, pathogens, such as Staphylococcus aureus, Salmonella serovars, Shigella spp., pathogenic
Esc. coli, norovirus, and hepatitis A, can be introduced into foods from human sources sometimes
through fecal-oral contamination.
Proper training of personnel in personal hygiene, regular checking of health, and maintaining
efficient sanitary and aesthetic standards are necessary to reduce contamination from this source.
Food Ingredients
In prepared or fabricated foods, many ingredients or additives are included in different quantities.
Many of these ingredients can be the source of both spoilage and pathogenic microorganisms. Various
spices generally have very high populations of mold and bacterial spores. Starch, sugar, and flour
might have spores of thermophilic bacteria. Pathogens have been isolated from dried coconut, eggs,
nuts, flours, and chocolate, and many of these ingredients were responsible for foodborne outbreaks.
The ingredients should be produced under sanitary conditions and given antimicrobial treatments. In addition, setting up acceptable microbial specifications for the ingredients will be
important in reducing microorganisms in food from this source.
Equipment
A wide variety of equipment is used in harvesting, transporting, slaughtering, processing, and
storing foods. Many types of microorganisms from air, raw foods, water, and personnel can get
into the equipment and contaminate foods. Depending on the environment (moisture, nutrients,
and temperature) and time, microorganisms can multiply and, even from a low initial population,
reach a high level and contaminate large volumes of foods. Also, when processing equipment is
used continuously for a long period of time, microorganisms initially present can multiply and act
as a continuous source of contamination in the product produced subsequently. In some equipment, small parts, inaccessible sections, and certain materials might not be efficiently cleaned and
sanitized. These dead spots can serve as sources of both pathogenic and spoilage microorganisms
in food. Small equipment, such as cutting boards, knives, spoons, and similar articles, because
of improper cleaning, can be sources of cross contamination. Salmonella, Listeria, Escherichia,
Enterococcus, Micrococcus, Pseudomonas, Lactobacillus, Leuconostoc, Clostridium, Bacillus spp., and
yeasts and molds can get into food from equipment (see Chapter 21).
Proper cleaning and sanitation of equipment at prescribed intervals are important to reduce
microbial levels in food. In addition, developing means to prevent or reduce contamination from
air, water, personnel, and insects is important. Finally, in designing the equipment, potential
microbiological problems need to be considered.