In this study, the existence of starch hydrolyzing enzymes in WBFB was investigated by attempting to produce glucose from soluble starch dissolved in the supernatant of WBFB which had been filtered in order to remove yeast cells. The concentration of glucose produced in the supernatant containing an additional soluble
tarch (Fig. 3A) was much higher than that in the bare supernatant
(Fig. 3B). It was ascertained that there was residual activity of starch
hydrolyzing enzymes because the glucose concentration increased
with incubation time as shown in Fig. 3. The glucose production
rate was faster at a higher temperature. The higher temperature
may also provide a suitable environment for the saccharification
of starch residues in WBFB because the optimum temperature of
the saccharification enzymes from malt is higher than 50 ◦C as
described in previous reports [20,28]. The CFU of yeast cell from
the filtrated supernatant of WBFB was not detected. The ethanol
concentration remained nearly constant during incubation time.