d. Green-Gilled Oysters. Green-gilled oysters are caused by the accumulation
in the gills and mantle of a bluish or greenish pigment derived from certain types of
algae and diatoms. The pigments are temporarily stored in the blood cells, filling up the
blood vessels of the gills and mantle. The color will be more internal in the gills than in
any other area of the body. This condition is not harmful if the oysters are consumed.
However, the condition lessens the quality of the oyster. It is not to be confused with
natural greenish color sometimes found in the stomach area and caused by excess
copper in the blood cells.
e. Gaper. A gaper is a dead oyster, one in which the valves are parted and will
not close when the oyster is disturbed. A gaper should not be included in a production
lot. Since the time of death is not known and the degree of deterioration is also
f. Measuring the pH Level. Measuring the acid value of oyster liquor is a fairly
accurate quality indicator since glycogen is converted to acid at a standard rate. At
origin, the oyster should have a 6.2 pH level, 6.0 at destination, and during surveillance
5.9 or 5.8.
2-13. DETERIORATIVE AND UNACCEPTABLE CONDITIONS OF SCALLOPS
a. Dark Gray or Black Scallops. Dark gray or black scallop is a condition that
develops when the scallops are not iced immediately after being caught. (Scallops are
normally shucked at sea with only the adductor muscle being retained, packed in cloth
bags, and then thoroughly iced.) This condition can also develop when the scallop is
held in a chill state for a long time prior to freezing. The condition starts as a light
grayish discoloration on the outside surfaces, becoming darker and penetrating inward.
Light gray scallops may be accepted by the inspector.
b. Diseased Scallops. Diseased scallops is a condition where small pink
nodules, approximately one-fourth inch in diameter, develop within the adductor muscle.
The nodules contain a pus-like fluid. The condition is not necessarily confined to the
surface. The cause of this condition is unknown. Any lot of scallops with evidence of
this disease is rejected.
c. Yellow-Tinged Scallops. Yellow tinges around the edges of scallops
2-14. DETERIORATIVE AND UNACCEPTABLE CONDITIONS OF SHRIMP
a. Black Spot or "Tigering." Black spot or "tigering" is a condition caused in
shrimp by enzyme reactions in the presence of oxygen. This black discoloration
develops where the segmented sections of the shell join together. There is a
blackening of melanin pigments in the shell membranes. The blackening appears as
black bands where shell segments overlap, giving the tail a banded (zebra or tiger)
appearance. This leaves a tigering appearance. This condition when confined to the