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To develop an effective utilization method of skipjack tuna viscera, fish meal by an improved fermentation method(FFMA) was prepared by fermentation of the solid materials separated from autoclaved viscera with Aspergillus oryzae for 72 hours and by adding the concentrated soluble extracts separated from autoclaved viscera to the fermenting solid materials during fermentation, and FFMA fish meal was compared with the fish meals prepared by Kato mathod(FFMN) and conventional nonfermenting method(NFM). FFMN fish meal was prepared by fermenting the solid materials separated from autoclaved viscera with Aspergillus oryzae for 17 hours without adding the soluble extract. The extracts from FFMA fish meal(FFMA-E) and raw viscera(RM-E) were also prepared respectively after digestion with proteases obtained from Bacillus subtilis and Aspergillus oryzae and compared with each other on the contents of free amino acids. The peroxide values decreased greatly in contents of vitamin B,, Bz and C significantly increased in FFMA fish meal compared with those of other fish meals. The total free amino acid content of FFMA-E was significantly higher then that of RM-E. The total free essential amino acid content also greatly increased in FFMA-E in which threonine, methionine and lysine showed remarkable increments. Almost all individual nonessential amino acids were higher in FFMA-E then in RM-E. The content of taurine, a nonprotein amino acid, greatly increased compared with other nonprotein amino acids in both extracts.
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