Characterization of fermented rice bran from 'Heshiko' and isolation of amylase-producing bacteria
2019
Nagaoka, J. (Tokyo University of Agriculture, Setagaya-ku, Tokyo (Japan). Faculty of Applied Bio-science) | Wada, K. | Katoh, M. | Fujita, N. | Tanaka, N. | Irisawa, T. | Akuzawa, S.
In this study, we characterized the main properties of the fermented rice bran around mackerel in the Japanese product Heshiko. We found increases in the moisture, lipids, and ash contents after fermentation, which was attributed to the effects of the Shiejiru added for filtration during the manufacturing process. However, there is no change of the general composition of the fermented rice bran of Heshiko with respect to the shipping time. We further characterized the non-starch, starch, and water-soluble polysaccharide fractions to understand better the chemical changes occurring as a result of enzyme and microbial action during fermentation. For instance, SEM photographs of non-starch and starch polysaccharides indicate the breakage of cell wall and surface of the starches. Furthermore, regarding the branch chain-length distribution pattern of amylopectin, we observed a decrease in the short chains of DP 6-12 and an increase in other chains of DP 13-20 in the fermented rice bran. Finally, we isolated amylase-producing bacteria from the fermented rice bran, which were estimated as Bacillus amyloliquefaciens (A1), Paenibacillus amylolyticus (A3), Bacillus subtilis (B1), Bacillus licheniformis (B2), and Oceanobacillus picturae (B3).
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