Combined use of rice-koji cultured with Aspergillus oryzae and Aspergillus luchuensis for enhanced dephosphorylation of phytate to myo-inositol in brown rice-koji-amazake, a sweet brown rice beverage

Abstract

Koji-amazake is a non-alcoholic sweet rice beverage popular in Japan, and commercial products are now available in Southeast Asian countries such as Thailand. It is made from boiled rice and rice-koji, a Japanese traditional fermentation starter using Aspergillus oryzae. The citrate-producing Aspergillus luchuensis is also used for the fermentation. Unpolished brown rice containing various nutrients is a promising ingredient; however, reduced phytate in the rice bran layer is desirable, as its strong chelating action may inhibit mineral absorption. Rice-koji made with A. luchuensis was found to be superior to that made with A. oryzae in dephosphorylation of phytate to myo-inositol in brown rice-koji-amazake. As citrate from A. luchuensis affects the flavor and degree of saccharification of the product, the combined use of rice-koji made with those two species should be considered to optimize the flavor and nutritional benefits of the product.