Changes in the amounts of water-soluble umami-related substances in porcine longissimus and biceps femoris muscles during moist heat cooking

Time course changes in amounts of glutamic acid, total free amino acid, inosine monophosphate (IMP), and 2%-trichloroacetic acid-soluble oligopeptides in whole, muscle only, and cooking juice during wet–heat cooking in pork longissimus and biceps femoris muscles were investigated because the movements of umami-relevant substances during cooking treatment had not previously been clarified in detail. The amounts of glutamic acid, total free amino acid, and IMP significantly (P < .05) decreased and increased in muscle and cooking juice during 180 min of cooking, respectively. The whole amounts of glutamic acid and total free amino acid remained unchanged during cooking treatment. The whole amount of IMP, however, increased significantly at 10 min of cooking (P < .05) and was maintained after the 10-min period. The extramuscular oligopeptides amount increased significantly in response to the cooking treatment (P < .05). The intramuscular amount of oligopeptides decreased at 30 min of cooking but increased significantly (P < .05) after 60 min. The whole meat oligopeptides amount increased significantly during a 180-min cooking treatment (P < .05). These results indicate that glutamate, total free amino acid, and IMP were released from the muscle during cooking, and that IMP levels increased in the initial phase of cooking. In addition, oligopeptides increased during wet–heat cooking of pork muscles.