Changes in Texture and Ingredients of Fresh-water Fish During Cooking

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Kanroni (sweet-boiled fish) and Koikoku (soy bean paste soup of carp) are typical traditional cookings in Japan. Cultured rainbow trout : Salmo gaidneri and cultured carp : Cyprinus carpio were used as the samples in these experiments.In Kanroni, the sensory tests indicated that the treatment of baking raw trout decreased fishy ordor and increased the hardness of the fish meat and tensile strength of the fish skin. The meat of Kannroni which is made of baked trout was harder and more fragile than Kanroni of nontreatment trout. The proteins exuded from fish meat and fish skin during cooking were less in the case of baked fish, and amount of water soluble proteins of it was kept in the meat of Kanroni. The treatment of baking raw trout before simmmering made the cooking of Kanroni easy and texture and flavor more palatable.In Koikoku, experiments were-conducted to examine the changes of texture and decomposition of constitutional proteins of fish during cooking by sensory tests, physical and chemical measurements. Instrumental test revealed that the hardness of the carp meat increased gradually during cooking, while those of bones and shales oppositely decreased. Similar changes in hardness and fragility were also detected by the sensory tests. When sake, rice wine, was added to the soup, . these characteristic. changes in the meat and the scale were more clearly observed both by the subjective and objective tests. Although long cooking time of 7-10 hours can be saved by using high-presser cooking pot in one hour, , the sensory test suggested the superiority in palatability for Koikoku by the ordinary cooking than the high-presser cooking.