Effects of cold storage, freezing and thawing on browning of cooked scallop adductor muscle

The effects of cold storage, freezing and thawing on the browning of scallop adductor muscle which occurs during the cooking process, were studied in relation to the content of glycogen, glucose and sugar phosphates (glucose-6-phosphate, fructose-6-phosphate, and fructose-l,S-diphosphate) in the muscle. The changes in content of glycogen, glucose and sugar phosphates were not observed in frozen muscle. Frozen muscle did not show browning after cooking at 110 degrees C for 90 min as unfrozen muscle immediately after death. During cold storage (5 degrees C) of unfrozen muscle, glycogen slowly decreased, glucose and sugar phosphates gradually increased, and browning of the muscle gradually increased. When frozen muscle was thawed either slowly (in still air at 0 degrees C) or rapidly (in running water at 15 degrees C), decrease in glycogen and substantial increases in glucose and sugar phosphates occurred, and strong brewing of the muscle during the cooking process was observed. During cold storage (5 degrees C) of thawed muscle, glycogen and sugar phosphates gradually decreased, whereas glucose considerably increased, and browning of the muscle gradually weakened. The content of glucose-6-phosphate and the degree of browning were closely related (r=0.85).