Partial hydrolysis of waxy rice starch by maltogenic α‐amylase to regulate its structures, rheological properties and digestibility

Summary Although different types of starch have been modified with maltogenic α‐amylase (MGA), its behaviour on waxy rice starch (WRS) remains obscure. This study aimed to modify cooked WRS with high concentration using MGA. The molecular weight of WRS decreased from 1.8 × 10 7 to 4.1 × 10 6 Da due to the exo – endo activity of MGA, while a high proportion of short branch chain and branching degree were generated as the degrees of hydrolysis (DH) increased. Intriguingly, no retrogradation occurred for the hydrolysates, even at DH 4.65%. Rheology reveal that the hydrolysate systems exhibited better fluidity and thixotropy. Furthermore, the resistant starch content of cooked WRS was elevated by 10.43% after MGA modification. The results indicate that MGA‐modified WRS was superior to other starches that have been reported in terms of inhibition of retrogradation and resistant starch content. Our data demonstrate the potential of enzyme‐based protocol for WRS modification using MGA alone to acquire clean and functional starch.