Effects of ll-amylase treatment conditions on the gelatinization and retrogradation characteristics of wheat starch

The study aims to investigate the change of gelatinization and retrogradation properties of wheat starch (WS) after ll-amylase treatment with different activities and different hydrolysis times, and to determine the relationship between the properties and treatment conditions. The contents of total starch, amylose and amylopectin in enzymatic treated samples were determined, and it was found that ll-amylase treatment hydrolyzed the samples and increased the amylopectin content. The rapid viscosity analysis (RVA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and total texture analysis (TPA) were used for investigation. The gelatinization temperature increased but the overall viscosity including the setback and AHg decreased with increasing ll-amylase activity or treatment time. Compared with WS, the hardness, AHr and recrystallization degree of samples decreased during storage, but the crystal structure still remained A-type. The crystallization rate constants of 10-50 U samples decreased by 25.1-41.9% and 10-50 min samples decreased by 7.6-54.6% according to the Avrami model. It was proved that the crystallization rate and retrogradation rate of the samples were slowed down. The results showed that ll-amylase treatment had both short-term and long-term inhibition effects on WS aging and there was a stronger correlation between processing time and effect. And higher ll-amylase activity had a stronger inhibition effect under the same hydrolysis time.