the product is handled and treated. Cells can be damaged in numerous ways, which
could result in excessive leakage of enzymes; hence, faster deterioration of the product.
Various ways of damaging cells are rough handling on the part of personnel, gnawing
by insects and rodents, ice crystal puncture due to improper freezing of the product, and
cell breakdown due to the action of microorganisms.
a. Method to Control the Action of Enzymes. There is no way to completely
prevent the leakage of enzymes from cells; therefore, methods have been developed to
control the action of enzymes, such as heat treatment (blanching) of some products to
inactivate enzymes and the addition of certain chemicals to prevent or retard the
oxidation of the product due to enzymes.
b. Other Types of Spoilage. The discussion above has suggested other types
of spoilage in addition to the two most common types, microbial action and enzyme
action. Other types of spoilage are the result of:
(1) Damage by insects and rodents, both direct and indirect (direct by eating
or gnawing, and indirect by contaminating with microorganisms).
Chemical changes such as oxidation (rancidity and browning).
(3) Physical changes such as excessive drying (desiccation or freezer
burn), wilting of vegetables, and so forth.
PRINCIPLES OF FOOD PRESERVATION
a. General Spoilage Control. The damage or spoilage of food products due to
microbial and enzyme action can be controlled adequately enough for man to consume
a relatively fresh product. Microbial spoilage is controlled by such measures as filtering
of liquids to eliminate the bulk of microbes; control of temperature either by heating or
cooling to retard the growth of microbes; control of the amount of oxygen by canning, to
create an unfavorable environment detrimental to the growth of microbes; addition of
chemicals and biological agents, such as nitrates/nitrites, antibiotics, and nonpathogenic
microorganisms, to create an environment unfavorable to the growth of pathogenic
microorganisms; and the use of very low temperatures, very high temperatures, and
b. Spoilage Control by Specific Methods, Programs, and Training. The
prevention of spoilage due to enzymatic action can be and is effectively accomplished
through such methods as the application of heat to inactivate enzymes; the addition of
antioxidants to prevent or delay the process of oxidation due to enzymes; the
establishment of good control programs for elimination of insects and rodents; and
through education and supervision of food handlers to prevent physical damage due to
rough handling and improper storage of products.