Microwave-assisted enzymatic hydrolysis: A sustainable approach for enhanced structural and functional properties of broken rice protein

Abstract

Design experiments having three levels of each processing parameter i.e.,α-amylase concentration (0.25–0.75%), extraction time (30–180 min), and temperature (30–60 °C) were conducted to investigate the effect of enzymatic pre-treatment on protein content and extracted yield from broken rice, an industrial by-product. Enzymatically pre-treated broken rice under optimal conditions (0.72% α-amylase concentration, 141 min extraction time, and 43°C of temperature) were subjected to microwave treatment followed by varying degrees (3%, 6%, 9%, and 12%) of enzymatic hydrolysis. The study revealed that the strongest free radical scavenging activity (72.35 ± 4.31 and 93.47 ± 1.25 μmol Trolox equivalent/g), highest magnitude of zeta potential (−24.95 ± 0.64 mV), and lowest mean particle size (446 ± 6.43 nm) were observed at MDH 12%. The FTIR analysis of MDH 12% (1650.08 cm−1) indicated a shift from random coil to β-turn, resulting unfolding of the rice protein structure and increased protein solubility. However, with an increase in DH, a negative effect on the foaming and emulsification properties of rice protein was observed. This study revealed that microwave-assisted enzymatic treatment with a 12% degree of hydrolysis can improve the functional properties of extracted protein and meet the demand for rice protein applications in different food formulations.