FOOD PRESERVATION
Section I. INTRODUCTION TO PRESERVATION OF FOODS
3-1.
INTRODUCTION
Plant and animal tissues are ultimately consumed by other organisms. A
competition exists between man, other animals, and microorganisms to see who will
consume these nutrients first. Because of this competition, man has utilized several
methods of food preservation to ensure that he will be the one to consume the nutrients
first.
3-2.
FOOD FIT FOR HUMAN CONSUMPTION
a. Definition. The statement "food fit for human consumption" should imply that
the food is at the desired stage of development or maturity. It is usually thought of as
ripe enough or cured enough to be aesthetically pleasant to eat. In various areas of the
United States, people have different ideas as to what is ripe enough or aged enough to
eat. However, most of us agree that a ripe tomato is red and that poultry is a tender,
young chicken rather than a stewing hen.
b. Objectionable Changes. Food must meet certain requirements as far as
pollution, contamination, or other objectionable changes are concerned. Food must be
free from human contamination, such as night soil (human feces used as fertilizers) on
fruits and vegetables, shellfish must not be contaminated by raw sewage, and no
contamination can exist from Staphylococcus growth (from skin lesions and oral and
nasal cavities of unsanitary food handlers) on red meats. Food should also be free of
contamination from insects and rodents that can serve as reservoirs for pathogenic
microorganisms. Other forms of contamination include chemical pollution (that is, heavy
metals (mercury) latent in fish) and soil-borne contaminants (dirt), which may be heavily
laden with bacteria, molds, and so forth.
3-3.
FOOD SPOILAGE--MICROBIAL ACTION
The two main causes of food spoilage are microbial decomposition and self-
decomposition with the help of enzyme action. Food is an excellent nutrient source for
microorganisms, nonpathogenic and, sometimes, pathogenic. Pathogenic organisms
are an important group that food handlers, processors, inspectors, and consumers are
concerned with due to the fact they may cause food poisoning; however, other
microorganisms are just as important due to their spoilage potential. Food is spoiled
more often by microorganisms than by any other factor. The microorganisms causing
spoilage are bacteria, yeasts, and molds. Microorganisms utilize the nutrients from food
in order to maintain their life processes and, consequently, cause food spoilage. An
example of food spoilage in nature is explained below.
MD0703
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