METHODS OF PRESERVATION
a. General. Most of the chemical changes in waterfoods can be controlled by
proper preservation. There are several methods employed to extend the shelf life of the
highly perishable waterfood products. Of these, there are six methods most commonly
used for troop issue items.
b. Icing. Icing is the method used for whole fresh or eviscerated fish and fresh
landed shell fish. The fish must be completely surrounded by ice and the container
equipped with drainage for the melted ice. Fresh fish are stored in containers, ranging
from 50-pound boxes to holds of fishing vessels with 10,000-pound plus capacity. A
layer of ice is placed on the bottom, then a layer of fish, and so on until the container is
filled and the last layer of fish is completely covered with ice. This is a short-term
storage, normally 7 to 10 days. The inspector will encounter iced fish only when
performing class 8 inspections for clubs and open messes and some limited
commissary resale operations. There are several disadvantages to icing.
(1) Spoilage bacteria will continue to reproduce at this temperature.
(2) The water will affect (bleach) the color of the flesh.
(3) Frequent reicing is necessary.
c. Freezing. Freezing is the primary method used for extended storage periods
for practically all forms: eviscerated fillets, fish portions, steaks, and processed
shellfish. Freezing provides a year-around supply of seasonal items. The major
advantage to freezing is an extended storage period (long-term storage). Methods of
freezing are conventional and quick frozen. If frozen rapidly, small ice crystals will
develop, resulting in a small drip loss when thawed. If conventional freezing methods
are used, large ice crystals will develop resulting in a large amount of drip loss.
(1) Conventional. The internal temperature must be reduced to 0o F within
(2) Quick frozen. The internal temperature must be reduced to 0o F within
one hour. This method is the one most commonly used.
d. Glazing. Glazing is used on a variety of products such as steaks, fillets,
eviscerated fish and practically all shellfish, though, for troop issue, primarily seen on
Form IV fish steaks. The product is frozen to 0o F (-18o F) by one of the methods above
and then dipped in cold water several times (at a temperature of 34o to 38o F) until a
protective layer of ice completely covers all surfaces, forming a glaze. Since glazing is
a method of preservation by the addition of another substance similar to packaging, a
means of determining the amount of glaze is required. This method will be discussed in
a subsequent part of this subcourse.