The effect of electrolyzed water on production of soybean functional low-molecular weight peptide by an Aspergillus oryzae protease

Abstract

The effectiveness of electrolyzed water from tap water on productivity of a functional peptide, which is derived from soybean protein by hydrolysis with a protease from Aspergillus oryzae, was examined. After mixing soybean powder (1 g) with a small amount of the protease (2 ma), the sample was added into three different water samples (10 ml), then incubated at 40°C. Water samples are neutral water (NW) after removing chlorine from tap water, electrolyzed cathode water (ECW) and electrolyzed anode water (EAW) obtained from the NW. A low-molecular weight peptide was produced in any water samples, however, the ECW sample contained the most abundant peptide. The peptide eliminated the DPPH radical very effectively. The concentration of residual SH group, retarding the oxidation of the soybean casein, of the peptide in the ECW and in the EAW samples, were 1.8 and 1.3 rimes higher than that in the NW, respectively. These results suggested that the ECW sample is suitable for producing a peptide with a high oxidation resistant ability. And the ECW sample raised the activities of the alkaline protease and the neutral protease, while the EAW sample activated the acidic protease. The mechanism raising protease activity in those electrolyzed water samples was also examined. The pH, ionic concentration and oxidation-reduction potential are suggested to be responsible concertedly with other properties of the water.