Abstract
As one of various applications of rice, a fruity fermented beverage can be prepared from a saccharified rice flour solution by using a lactic acid bacterium isolated from kefir. The degree of fermentation in the preparation of the beverage varied according to the commercial saccharifying enzyme preparation (glucoamylase [Amano] or gluczyme) that was used in the saccharification reaction. This difference is assumed to have been caused by the action of products obtained from the autolysis of gluczyme due to contaminated protease.
The contents of free amino acids in gluczyme after incubating at 56 °C were markedly increased by autolysis, and acid formation of the kefir bacterium in the glucoamylase-treated saccharified solution was stimulated by the addition of a slight amount of incubated gluczyme. The effect of the TLC-active fraction of autolyzed gluczyme on the acid formation of lactic acid bacteria and the effects of the addition of known amino acids enabled the main growth stimulant to be identified as isoleucine, in addition to valine and leucine which had a synergistic effect.
