Environmental Engineering Reference
In-Depth Information
Staphylococcus
•
Yersinia
•
Because of the practical difficulty of permanently eliminating all mice and
rats, the threat of contaminating food with the organisms causing the foregoing
diseases is ever present. This emphasizes the additional necessity of keeping all
food covered and protected.
Dust, eggs, poultry, pigs, sheep, cattle and animal feed, rabbits, rats, cats, and
dogs may harbor
salmonella
and other causative organisms. shelled eggs and egg
powder may also contain
salmonella
.
Salmonella
food infection is common and
routinely causes non-life-threatening in healthy individuals
FOOD SPOILAGE
When fresh foods are allowed to stand at room temperature, they begin to dete-
riorate. The changes in the composition of the food are brought about by the
action of enzymes and microorganisms, including molds and yeasts. Factors
such as oxygen, sunlight, warmth, dehydration, insects, and other vermin accel-
erate decomposition, contributing to the unpleasant appearance and taste of the
food, the loss of freshness, and changes in the color and odor. Food that has
been permitted to decompose loses much of its nutritive value. Atmospheric
oxidation causes a reduction of the vitamin content and quality, a breakdown
of the fats, then the proteins, to form hydrogen sulfide, ammonia, and other
products of decay. Antioxidants are sometimes used to slow down food dete-
rioration, rancidity, or discoloration due to oxidation. These include ascorbic
acid, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), cit-
ric acid, and phosphates. The Food and Drug Administration (FDA) requires
that ingredient labels carry and list the antioxidants as well as their carriers.
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Contamination, which almost always accompanies putrefaction, may be danger-
ous. In certain instances, the microbiological activity will produce a toxin (e.g
Staphylococcus aureus
toxin) that even ordinary cooking cannot destroy. Most
bacteria associated with food spoilage will grow within a wide pH range, from
3.0 or 4.0 to 8.0 or 9.3. Yeasts and molds also grow within a very wide pH
range, from 1.5 to 8.5 or 11.0. Foods with pH values below 4.5 are usually not
easily spoiled by bacteria but are more susceptible to spoilage by yeasts and
molds.
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Mycotoxins are secondary meabolites produced by several groups of fungi,
including those in the genera
Aspergillus, Penicillium, and Fusarium
. Mycotoxins
may contaminate human or animal food, resulting in a toxic response when
ingested. The toxic effects of mycotoxin ingestion depend on several factors,
including the amount and type of toxin ingested and the duration of exposure
to the toxin. In addition to causing acute toxicity, some mycotoxins may have
teratogenic and carcinogenic effects.
