Characterization of chestnut starch acetate with different degrees of substitution

Chestnut starch acetates (CSA) with different degrees of substitution (DS) were prepared. The structure and physicochemical properties of CSA were then determined, with scanning electron microscopy showing that most of the CSA granules were damaged and dented, and adhered with increased in DS. X-ray diffraction results indicated that the crystal form of CS and CSA was type C. Chemical structure analysis showed that the starch molecule was grafted with acetyl groups. The transparency, freeze–thaw stability, solubility and swelling power of CSA improved with an increase in DS. The viscosity and stability of CSA were significantly improved and pasting temperatures reduced compared with native CS. The cohesion, hardness, gumminess, chewiness and springiness of CSA decreased with an increase in DS, whereas adhesiveness increased. By comparing the properties of CSA with different DS, a new option was provided for the application of renewable natural polymer CSA in food fields.

Structural, physicochemical and long-term retrogradation properties of wheat starch treated using transglucosidase

To reduce the wheat-flour-based food texture and flavor deterioration caused by starch retrogradation, herein wheat starch, the most ingredient in wheat flour, was modified by transglucosidase to delay long-term retrogradation of wheat starch. The study proposed promising data of transglucosidase-treated starch about structure, crystallinity and retrogradation kinetics. Structural properties showed that transglucosidase treatment shortened the average chain length from 19.49 to 16.10 and induced the dominance of amorphous state. Moreover, branching degree increased from 14.11% to 17.97% after transglucosidase treatment, resulting in higher water mobility. Amylose content increased from 25.33% to 59.00% due to the hydrolysis ability of transglucosidase. Relative crystallinity of the retrograded starches decreased from 24.33% to 14.50%. Furthermore, the Avrami parameters demonstrated that transglucosidase treatment significantly retarded the retrogradation rate of wheat starch due to the decrease of re-crystalline rate. The outcoming would supply a solid theory foundation for exploring the wheat staple foods with higher qualities.