Structure and Physicochemical Properties of Malate Starches from Corn, Potato, and Wrinkled Pea Starches.

In this study, corn, potato, and wrinkled pea starches were esterified with malic acid under high temperatures for different lengths of time. The degree of substitution (DS), granule morphology, crystal structure, gelatinization properties, and the digestibility of the malate starch were investigated. Fourier transform infrared spectroscopy (FT-IR) suggested that the malate starch showed a new infrared absorption peak near 1747 cm^-1, indicating the occurrence of an esterification reaction. With an increasing treatment time, the degree of substitution (DS) of the malate starch displayed an increasing trend. Scanning electron microscopy (SEM) demonstrated a significant change in the surface structure of the starch granules. X-ray diffractometry (XRD) reflected that the crystal structure of the malate starches was destroyed. The thermogravimetric (TG) curves showed that the maximum heat loss rate of the malate starch was ahead of that of native starch, which caused the decreased degree of crystallinity. These properties of malate starch could allow it to be used for the purpose of starch modification to produce resistant starch and to provide new applications for starch.