Effect of superheated steam treatment on enzymes related to lipid oxidation of brown rice

Abstract

When brown rice is preserved for a long period of time, a stale flavor (komai-shu) develops as a result of lipid oxidation by enzymes. In order to inactivate the enzymes, brown rice was treated with superheated steam. Superheated steam treatment for about 1 min, at all temperatures, caused a decrease in the enzymatic activity related lipid oxidation. On the other hand, the degree of starch damage did not increase during superheated steam treatment below 150°C. These results show that superheated steam treatment at a low temperature and for a short time is enough to inactivate the enzyme in brown rice, and does not influence starch quality. It was expected that enzyme inactivation by superheated steam treatment would be effective in suppressing the generation of stale flavor during long preservation periods.