Influence of moisture and amylose on the physicochemical properties of rice starch during heat treatment

Moisture and amylose are important factors affecting the quality of heat-treated starches. The amylose content in heat-treated rice starch increased as moisture content (MC) increased from 8% to 30%, but decreased at MC of 70%. With the increase of MC, the paste transmittance, gelatinization temperature, and digestibility of starch increased, whereas the swelling power and enthalpy decreased. The long- and short-range molecular order and the digestive properties of starch with MC <= 30% changed moderately, but high MC (70%) gelatinized the starch and drastically changed the physicochemical properties. High amylose content in rice starch led to low long- and short-range molecular order, swelling power, and gelatinization temperature, but increased resistant starch. The results indicated that 30% of MC separates effects of heat treatment of starch, where low MC (<= 30%) and high amylose lowers digestibility, which is beneficial for diabetics, while high MC (>30%) promotes solubility and transparency. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Moisture and amylose content play crucial roles in determining the quality of heat-treated starches. Increasing moisture content leads to higher paste transmittance, gelatinization temperature, and digestibility, while decreasing swelling power and enthalpy. Higher amylose content in rice starch decreases molecular order and gelatinization temperature, but increases resistant starch.