Characteristics of raw soy sauce for cooked rice

Abstract

This study compared the cooking characteristics of raw soy sauce, in which various enzymes are active, with those of heat-treated soy sauce in the preparation of cooked rice takikomi gohan.

There was no significant difference in the gelatinization ratio between the rice cooked with both soy sauces. As for the colour tone of the cooked rice, the use of raw soy sauce made it possible to prepare light rice with a bright and subtle redness. In the case of high salinity (2.0% (w/w) added salt concentration against rice), the results of the breaking and brittleness forces showed that cooked rice is softer and less brittle when prepared with raw soy sauce than when prepared with heat-treated soy sauce. In addition, the amount of reducing sugar was significantly higher in cooked rice prepared with raw soy sauce compared to that prepared with heat-treated soy sauce, which was consistent with the sensory test results, suggesting that a cooked rice with a sweeter flavour can be better prepared with raw soy sauce than with heat-treated soy sauce.

As a result, the use of raw soy sauce provided different food textures and tastes compared to the heat-treated soy sauce owing to the function of starch-degrading enzymes, such as α-amylase, and other enzymes.