Effect of Annealing on Structural, Physicochemical, and In Vitro Digestive Properties of Starch from Castanopsis sclerophylla

Annealing is a hydrothermal treatment that changes the structural and functional properties of starches. This study investigates and compares the effects of one-step annealing for 24 and 48 h, respectively, and two-step annealing on the structural, physicochemical, and digestive properties of Castanopsis sclerophylla starch (CaS). Annealing has no effect on CaS morphology, crystalline pattern, and short-range ordered structures. However, annealing decreases the swelling power, solubility, setback, and peak viscosity of CaS and increases its crystallinity and thermal stability. Post annealing, the rapidly digestible starch (RDS) of CaS decreases, the slowly digestible starch (SDS) increases while the resistant starch (RS) content of CaS remains unchanged. Comparing with One-step annealing for 24 h, one-step annealing for 48 h and two-step annealing does not further change the RDS and SDS content of annealed CaS.