Retrogradation properties and in vitro digestibility of wild starch from Castanopsis sclerophylla

Abstract

In order to explore the application of a new starch source isolated from Castanopsis Sclerophylla, the retrogradation properties and in vitro digestibility of C. Sclerophylla starch (CaS) were investigated for the first time in this study. The Chain-length distribution (CLD) of amylopectin from CaS was characterized. The retrogradation behavior of CaS was measured using rapid viscosity analysis (RVA), rheometry, texture profile analysis (TPA), and differential scanning calorimetry (DSC), and the results compared with those of corn starch (CS). Cas amylopectin displays a lower proportion of short chains (A-chains, 13.31%) and higher proportion of long chains (B3-chains, 31.70%) when compared to corn amylopectin. CaS has a high rate of retrogradation, with higher setback, storage modulus (G′), and lower Tan δ values than CS in short-term retrogradation. CaS gels showed increased hardness and released water from starch gels during storage. Compared with CS, native CaS exhibited higher SDS content and lower RS content and estimated glycemic index (eGI) value. Retrogradation greatly increased the RS content in retrograded CaS and was almost five times higher than that obtained for native CaS after 7 days of storage at 4 °C, whereas it was only slightly higher than that in CS. Furthermore, retrogradation significantly decreased the eGI of CaS, indicating a potential application of CaS in functional food.