Preparation of yam starch acetates by using ultrasonic-assisted method and characterization of its products
The feature of ultrasound on esterification of yam starch were investigated by comparing the effects of ultrasound with preparation without ultrasound on the degree of substitution of yam starch acetates. In addition, the influences of ultrasonic wave on the particle shape, particle size, crystallinity and thermostability of yam starch acetates were analyzed by means of SEM, XRD, TG and DTA. The results of research showed that: the enhancement effects of ultrasound on esterification of yam starch can shorten the reaction time, and decrease the amount of catalyst. The results of XRD, SEM, TG and DTA showed that: the ultrasound can degrade the yam starch, and damage the crystallinity of yam starch acetates. The reactive area between yam starch and acetylating agent can increased with enhancement effects of ultrasound. The influences of ultrasound on the crystallinity of yam starch acetates are feeble, so the ultrasound has little influence on the thermostability of yam starch acetates.