Exploring the effect of mold fermentation on the taste and flavor properties of traditional Japanese smoked-dried bonito (katsuobushi)

Abstract

The present study aimed to investigate the differences in the physicochemical properties, taste characteristics, and flavor compounds of Katsuobushi, a traditional Japanese smoked-dried bonito product, including Arabushi (unfermented) and Karebushi (mold-fermented), as well as the effects of surface fermentation on the internal, middle, and external of Karebushi products. The findings showed that mold fermentation could be an effective method for improving the color characteristics of Katsuobushi. Karebushi possessed the highest content of flavorful amino acids and nucleotides, which synergistically enhanced the level of umami taste profiles. Notably, the EUC value of the exterior (12.51 g MSG/100 g) is significantly higher than that of the interior (8.81 g MSG/100 g), which means that the surface fermentation imparts a stronger umami taste to the exterior. In addition, the abundance of organic acids in the Karebushi helped to improve the umami and sweet tastes. The electronic nose and fingerprint profiles revealed that Karebushi was found to have higher types and contents of flavor compounds than Arabushi. 3-Methyl-1-butanol, 2,5-dimethylpyrazine, and α-pinene are the characteristic volatile aroma components of Karebushi, contributing to the exceptional malty, nutty, and roasted aroma. This study may be conducive to a better understanding of the effect of mold surface fermentation on the flavor characteristics of Katsuobushi, and provide a theoretical basis for the development of appropriate start cultures.