Improvement of structural, physicochemical, functional, and pasting properties and mass balance analysis of porous starch obtained from Indonesian local rice through microwave-assisted enzymatic hydrolysis

Abstract

This study aims to examine the impact of microwave treatment, enzymatic hydrolysis, and microwave-assisted enzymatic hydrolysis on the characteristics of porous rice starch. Microwave irradiation was applied to rice starch at 171 W g⁻¹ for 15 s. Enzymatic hydrolysis was carried out using 100 U per g α-amylase and 100 U per g amyloglucosidase at 60 °C for 8 h in rice starch and 0.1 M CH₃COONa buffer at pH 5.2. The results showed that among the samples, porous rice starch acquired by microwave-assisted enzymatic hydrolysis (MES) showed an increase in pore structure, crystallinity, solubility, pasting temperature, and adsorption ability, with oil and methylene blue uptake increased by 124.5 ± 2.80–158.45 ± 5.40% and 35.72 ± 3.66–53.67 ± 1.77% (P < 0.05), respectively. Pasting properties analysis indicates a significant decline in pasting, breakdown, final, and setback viscosity. Based on the findings of crystallinity tests, all samples showed crystal type A. In accordance with mass balance calculations, the mass of the incoming or outgoing materials of MES is 31.19 g, and the yield of MES obtained is 60.39 ± 0.72%. This study established that compared with microwave or enzymatic treatment, the microwave-initiated enzymatic method has great potential and novelty in porous rice starch production.