Production of resistant starch from rice by dual autoclaving-retrogradation treatment: Invitro digestibility, thermal and structural characterization

Abstract

In this work, a dual autoclaving-retrogradation treatment was designed for preparing resistant starch from four rice cultivars and its impact on invitro digestibility, pasting, thermal and structural properties was determined. Dual autoclaving-retrogradation treatment resulted in significant increase in resistant starch yield, water and oil absorption capacity, transmittance, freeze thaw stability, and bile acid binding with decrease in solubility and swelling index. In general, all RVA (Rapid visco analyser) parameters, except peak time and pasting temperature, of treated starches were significantly lower than those of native ones. Post autoclaving-retrogradation treatment, To, Tp, Tc and ΔH shifted to higher values with a decrease in transition temperature range (Tc -To). Fourier transform infrared (FT-IR) spectroscopy showed increased intensity at 1047 cm −1 in treated starches. Scanning electron microscopy studies revealed that the microstructure of treated starches showed a continuous dense network with irregular shape. Results of the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and reducing power revealed significant increase in antioxidant activity of starch with treatment.