Preparation and properties of RS4 citrate sweet potato starch by heat-moisture treatment
2016
Xia, Huiping | Li, Yunyun | Gao, Qunyu
Sweet potato starch (SPS) granules were firstly subjected to heat-moisture treatment (HMT) and then esterified with citric acid (CA). The physicochemical properties of CA-starch and heat moisture treatment citric acid starch (HMT-CA-starch) were investigated. Results showed that the high dosage of CA significantly increased the degree of substitution (DS) and the resistant starch (RS) content of the CA-starch (P < 0.05). With HMT, the RS content of HMT-CA-starch was effectively increased compared to the controls. Scanning Electron Microscopy (SEM) pictures showed that the shape and integrity of HMT-starch granules did not change but concavity was observed. However, CA-starch and HMT-CA-starch appeared collapses and fragments. The spectra of Fourier-transform infrared spectroscopy (FT-IR) indicted that the esterification of HMT-CA-starch was stronger than the CA-starch. Crystal structure of CA-starch remained unchanged, while that of HMT-CA-starch changed from A-type to C-type compared to HMT-starch. The relative crystallinity (RC) of HMT-starch, CA-starch and HMT-CA starch was decreased. The gelatinization temperatures (To, Tp, and Tc), enthalpy of gelatinization (ΔH) and swelling power decreased sharply in all CA-starches compared with the controls. All results indicated that HMT increased the accessibility of the starch granules and made it easier for CA to penetrate into the starch granules.
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