Effect of heat-moisture treatment on the physicochemical properties of waxy wheat starch

Objective The effect of heat-moisture treatment (HMT) including time, temperature and water content, on the physicochemical properties of waxy wheat starch was investigated.

Method The pasting properties such as clarity, solubility, swelling power, freeze-thaw stability, morphology, and X-ray crystallinity of the starch were evaluated.

Result and conclusion HMT reduced the transparency, solubility and freeze-thaw stability of waxy wheat starch. However, the swelling power of waxy wheat starch decreased and then increased. HMT did not obviously change the particle shape and size of starch granules, but the surface of starch granules became uneven, and the central of the granules became blurred; some crack and indentation appeared. HMT reduced the birefringence intensity of starch granules. The X-ray diffractometry result revealed that HMT promoted a reduction in the starch relative crystallinity, but the native and HMT starch maintained the A diffraction pattern.