Extractive Components in the Ordinary and Dark Muscles of Katsuobushi Manufactured by Different Processes

Abstract

We compared the extractive components of the ordinary and dark muscle portions contained in hongarebushi and arabushi, both of which were produced by different katsuobushi-manufacturing processes. Taurine, histidine, and anserine were abundant among the free amino acids contained in both of the fushi types and muscle portions. In hongarebushi, taurine was richer in the ordinary muscle than in the dark muscle. Histidine and anserine were also abundant in the ordinary muscle in both of the fushi types. There was no significant difference in the composition of the bound amino acids compared to that of the free amino acids. Inosine monophosphate (IMP) was richer in the ordinary muscle than in the dark muscle, and there was little difference in inosine content between the muscle portions. The contents of compounds, such as creatine, creatinine, lactic acid, moisture and extractive nitrogen were higher in the ordinary muscle. Umami strength, calculated from both the IMP and glutamic acid contents, was found to be significantly higher in the ordinary muscle than in the dark muscle, but not between the fushi types.