The effects of sequential enzyme modifications on structural and physicochemical properties of sweet potato starch granules.

Abstract

Sweet potato starch products possess unacceptable hardness and poor transparency that in-turn reduces consumer acceptability. To expand the sweet potato starch utility with user acceptable and palatable food products herein enzyme modification has been carried out. Transglucosidase (TGAN) in combination with maltogenic α-amylase (MABS) and β-amylase (BA) appears to be advantageous to modulate sweet potato starch properties. The MABS → BA → TGAN treatment increases the α-1, 6 glycosidic linkage ratio and short chain proportions (DP ≤ 24). Decrease in chain length, molecular weight and long chain proportions (DP > 24) is noticed. The initial C-type starch polymorphic structure transforms to B-type structure along with decreased crystallinity. Solubility increases substantially with concomitant decrease in viscosity, gelatinization temperature and melting enthalpy. The outcome is believed to open new pathways for regulating the physicochemical properties of sweet potato starch especially by enzyme modification to the design and development of novel sweet potato starch-based products.