a. Age. All foodstuffs are subject to varying degrees of natural deterioration.
This deterioration is inherent in the food itself. It should not, however, be confused with
action of microorganisms, chemical agents, or other outside agents.
b. Microorganisms. Most perishable items deteriorate or spoil because of the
action of microorganisms, especially bacteria, yeasts, and molds. Actions of
microorganisms cause gas to form and this produces objectionable odors and taste.
Some swellers in canned goods are the result of action by microorganisms.
c. Insects. Insects can cause great damage to stored food. They may attack
both natural and manufactured food. Food stored at temperatures between 60Ε and
90F is especially attractive to insects. Infested supplies must be segregated and, if not
too heavily infested, may be "reconditioned" for use.
d. Rodents. Rodents not only physically destroy food by feeding, chewing, and
cutting the bags for nests or nesting material. Rodents also contaminate food with their
excreta and hairs. Rodents are carriers of filth and disease; the importance of
controlling these pests is evident. The most effective method of control is to prevent
entry of these animals.
e. Environmental Factors.
(1) Freezing. Freezing temperatures normally do not harm dry products,
such as grains, flour, sugar, starch, cereals, and dehydrated foods, but products with
large amounts of water, such as canned goods, will freeze and possibly burst. If the
container does not rupture, the product inside may suffer changes in consistency and
texture. Emulsions that separate when frozen, such as mayonnaise and mustard, can
be recombined with the proper equipment.
(2) Heat (high temperatures). High temperatures are detrimental to canned
goods and greatly shorten storage life of all subsistence because such temperatures
accelerate the natural deterioration. High temperatures also speed up chemical
reactions, such as oxidation and rancidity in fatty foods, or interaction between high acid
content subsistence and metal cans and cause pinholing, spangling, hydrogen swells,
or denting. A rule of thumb commonly used is that each rise of 18F (10C) above a
specified storage temperature doubles the rate of deterioration. Subsistence stored at
high temperatures is particularly susceptible to insect infestation and will require
(3) Moisture (humidity). High humidity is detrimental in many respects. It
accelerates the growth of bacteria and molds. It promotes insect infestation, it causes
mustiness in flour, rice, and similar foods. High humidity causes products which readily
absorb moisture, such as sugar and salt, to cake and become hard. Storage of
perishable items at high relative humidities may allow water to condense upon or to be
absorbed into the item. At lower relative humidities, the item may dry and shrink.