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 l2 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.