Vinegar Production by the Static Fermentation of Subcritical Water - Treated Mixtures of Sake Lees and Rice Bran

Author(s): Shoji Hirayama, Sae Namba, Takachika Hoshino, Yuriko Hoshino, Kazuharu Yamato, Munehiro Hoshino, Mitsuru Sasaki

Sake lees and rice bran are major by-products of the Japanese food industry. As these by-products are discarded in large quantities, sustainable approaches to utilize these feedstocks are needed. We therefore investigated the production of vinegar through static fermentation using a mixture of subcritical water–treated sake lees and rice bran. Subcritical water treatment was previously shown to promote the liquefaction of these by-products to generate solutions rich in amino acids and minerals. In this study, we prepared subcritical water–treated sake lees and rice bran solutions at various mixing ratios and examined the effect on vinegar production. The amino acid and mineral content of the vinegar varied depending on the mixing ratio, and the higher the mixing ratio of subcritical sake lees solution, the higher the amino acid concentration, and the higher the mixing ratio of subcritical rice bran solution, the higher the carbohydrate and mineral content. This study proposes a method for producing vinegar with high nutritional value comparable to conventional products by reusing by-products from the Japanese food industry.