INSPECTION OF SHELLFISH
Shellfish are differentiated from fish by their skeletal structure, which is
exoskeletal. For the purpose of this subcourse, they are further divided into two types:
(1) mollusks: oysters, clams, and scallops; and (2) crustaceans: shrimps, crabs,
and lobsters. Their chemical composition is basically the same as fish, with some
exceptions. Although the amount of shellfish procured by the military is small
poundage-wise, the dollar value is significant. A basic knowledge of their anatomical
features is necessary to the inspector so that deteriorative conditions can be better
2-2. CHEMICAL COMPONENTS
The basic chemical components of shellfish that are of importance to the
a. Water. Water is the largest component, averaging 80%. Some shellfish have
a tendency to absorb water. Therefore, a water contact time has been established
during processing. This is an origin inspection responsibility.
b. Carbohydrates. Shellfish contain a measurable amount of carbohydrates.
Approximately 0.5% to 6% carbohydrates are found in shellfish. Most of this component
is converted to lactic acid during bacterial growth. As a result, the pH value can be
measured and is used as a quick quality indicator for freshness of oysters.
c. Protein. Shellfish flesh contains 10% to 16% protein, averaging 14%. It is
like that found in fish. This protein contains amino acids required by man in his daily
d. Fat. There is less than 2% fat; therefore, rancidity is not as much a problem
as in fish.
e. Minerals and Vitamins. Combined, minerals and vitamins average
approximately 2%. Practically every chemical element contained in sea water may be
found in shellfish.