Chestnut is popular worldwide for its unique flavor, high eating quality and nutrition. Here, we evaluated the influence of phosphorylation and acetylation on the structural, physicochemical and functional properties of chestnut starch. Scanning electron micrographs showed the agglomeration of starch granules and the appearance of numerous dents on the starch granule surface under phosphorylation and acetylation. X-ray diffractograms confirmed that the modification treatments did not affect the C-type crystal pattern, but reduced the relative crystallinity of the chestnut starch, particularly phosphorylation. Moreover, modification improved the paste transparency of the starch. Differential scanning calorimeter analysis revealed that the gelatinization temperature and enthalpy of the starch decreased with the increasing substitution degree, particularly in phosphorylated starch. The Rapid Visco Analyser analysis demonstrated that phosphorylation could greatly improve the pasting properties of chestnut starch. In addition, phosphorylated and acetylated starch had a smaller amount of slowly digested starch and a larger amount of resistant starch relative to native chestnut starch. In conclusion, the functional and physicochemical properties of chestnut starch can be significantly improved through phosphorylation and acetylation, demonstrating its great application potential as a food additive.
Keywords: acetylation; chemical modifications; chestnut starch; phosphorylation; physicochemical properties.