Effects of ultrasonic and enzymatic treatment on physical and chemical properties of brown rice

Abstract

AbstractBrown rice (Oryza sativa Linn.) was subjected to ultrasonic treatment (UT) and enzymatic treatment (ET) with cellulase (CT), glucoamylase (GT), and α‐amylase (AT). UT showed no significant effect on thermal properties, crystalline pattern and, glycemic response of brown rice. AT decreased gelatinization enthalpy from 7.19 g/J (control) to 5.31 g/J and reduced degree of crystallinity from 23.06% (control) to 21.02%. These changes significantly increased glycemic index of AT brown rice. CT and GT had insignificant effect on crystallinity and thermal properties of rice. Both UT and ET decreased hardness of cooked rice from 206.05 to 189.63–148.87 N in which the AT cooked rice was the softest. Both AT and UT were potentially used as novel processes to develop the soften brown rice. However, UT brown rice had lower glycemic response, required shorter cooking time, and was more practically produced in industrial scale than ET brown rice.Practical applicationsSoaking is the hydration process, which is normally used for brown rice before cooking. However, it is inconvenient and time‐consuming. Results of this study revealed the effects of enzymatic and ultrasonic treatments (UTs) on modifying of the bran layer and changing of physiochemical properties of rice grains. These changes promoted water uptake, reduced hardness, and improved cooking properties of brown rice. In consideration of glycemic response, UT represents good practice in the production of soften brown rice without soaking before cooking.