. Commercial fisheries review. Fisheries; Fish trade. 15 COIf«RCLAL FISHERI>]S RSVISW Vol. 14, No. 12a freezing studies= The bulk of the data was obtained using the same 30 by 30 by 30-inch tank with the rotating screen drum. Several semi-commercial trials were made in a tank, 8 by 3 by 3 feet (figures 5 and 6) equipped with a l/3-hpo cen- trifugal purap to circulate the water^ This tank was supplied with cold-water (42**?. to 65°F.) and hot-water (150° F.) inlets and with adequate overflow arrange- ments. Whole round haddock and cod frozen in the course of the pilot-plant freez- ing studie
. Commercial fisheries review. Fisheries; Fish trade. 15 COIf«RCLAL FISHERI>]S RSVISW Vol. 14, No. 12a freezing studies= The bulk of the data was obtained using the same 30 by 30 by 30-inch tank with the rotating screen drum. Several semi-commercial trials were made in a tank, 8 by 3 by 3 feet (figures 5 and 6) equipped with a l/3-hpo cen- trifugal purap to circulate the water^ This tank was supplied with cold-water (42**?. to 65°F.) and hot-water (150° F.) inlets and with adequate overflow arrange- ments. Whole round haddock and cod frozen in the course of the pilot-plant freez- ing studies were used in most of the thawing trials« For a few of the large-scale thawing experiments, fish which had been frozen in brine aboard the Delaware were employed. The progress of thawing was followed by occasionally cutting one or more fish with a sharp, sturdy knife and measuring the thickness of the thawed layer. The line between the thawed meat of the fish and the still frozen meat was quite clear and definite. During at least the first four hours of thawing, unless the fish were old and soft (from repeated freezing and thawing), the thickness of the thaw- ed layer could be estimated to within l/l6 of an inch. The temperatures at vari- ous depths were determined by inserting a thin-stemmed metal at sev- eral points in cross-sectional cuts. After 30 minutes of thawing, the temperature of the center of a cod or haddock, weighing from 1 to 15 pounds, had risen to be- tween 25° F. and 30° F. The borderline between the frozen and thawed layers was between 30° F. and 32° F. The temperature of a given point in the thawed layer depended on the location of the point and on the temperature of the thawing water. Figure 6 il- lustrates the rate of thawing of a 10-pound cod, near the thickest part of the fish, when it was mov- ed through 60° F. fresh water at about 10feet per minute. By com- paring figures 3 and 6 it will be seenthat thawingin waterproceeds in much
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