Prebiotic potential and characterization of resistant starch developed from four Himalayan rice cultivars using β-amylase and transglucosidase enzymes

Abstract

In the present work, resistant starch (RS) was developed from four Himalayan rice cultivars by using enzymatic treatment with β-amylase and transglucosidase enzymes so as to make them the potential prebiotic. Thereafter, the prebiotic potential of resistant starch was confirmed by their invitro fermentation using selected probiotic strains. Fermentation of RS by Lactobacilli resulted in the production of 276.45–300.15 μg/mL of acetic acid, 0.40–0.83 μg/mL of propionic acid and 0.73–1.94 μg/mL of butyric acid. The capability of resistant starches to produce the SCFA (Short chain fatty acids) including butyrate confirmed their potential as substrates for beneficial colon bacteria. In general, pasting properties of resistant starch samples were significantly (p ≤ 0.05) lower than native rice starch samples. Resistant starches exhibited shear-thinning behaviour. The DSC results revealed significant decrease in the gelatinization temperatures and enthalpy (ΔH) of resistant starches. The resistant starches completely lost their granular integrity and formed a continuous compact fibrous network with irregular shape. XRD analysis revealed the formation of amylose–lipid complexes during the treatment. The decreased intensity at 1047 cm−1 in resistant starches reveals their lower crystallinity. The study revealed that enzymatic treatment of rice starch significantly increased their production of SCFA thereby making them potential prebiotic.