Abstract
Maturation of chum salmon (Oncorhynchus keta) leads to nuptial coloration, deterioration and a decrease in the fat content of muscle. Consequeutly, overmatured salmon has no commercial value. In this study, to find an effective use for overmatured salmon, we applied dried fish manufacturing such as dried skipjack (Katsuobushi) on these salmon. However, dried salmon (Sakebushi) manufactured according to the ordinary Katsuobushi manufacturing process had low extractive components and showed little umami. In order to increase the extractive components, a few modifications were introduced to Katsuobushi manufacturing process; the boiling process was changed to a steaming process, and mild enzymatic proteolysis was applied before the steaming process. By the modified procedure, extractive nitrogen of Sakebushi increased 2.5 times as much as that by the ordinary procedure. As compared with commercially available Katsuobushi and dried mackerel (Sababushi), extractive nitrogen of the Sakebushi was 30% and 60% higher than that of Katsuobushi and Sakebushi, respectively, and in particular, glutamic acid in Sakebushi was 12 and 4 times higher as well. But inosinic acid of the extract of Sakebushi was significantly lower than that of the others. Sensory evaluation indicated that Sakebushi had low bitterness and sufficient umami as much as Katsuobushi and Sababushi.
