Characterization of acetylated corn starch prepared under ultrahigh pressure (UHP)

To investigate the impact of ultrahigh pressure (UHP) on the physicochemical properties of the UHP-assisted starch acetate, common corn starch was subjected to either conventional (0.1 MPa, 30 degrees C, 60 min) or UHP-assisted (400 MPa, 25 degrees C, 15 min) acetylation reactions at three levels (4, 8, or 12%) of acetic anhydride. Without significant changes in starch granule crystal structure, UHP-assisted reaction exhibited lower degree of substitution values than conventional reaction across reagent addition levels. An increase in reagent addition levels exhibited common trends in starch solubility/swelling power, gelatinization, and pasting properties for the conventional and UHP-assisted starch acetates relative to native starch. Within an equivalent derivatization level, however, the UHP-assisted (relative to conventional) starch acetates revealed restricted starch solubility/swelling power, reduced gelatinization temperatures, and lower pasting viscosities. Overall, this result suggested that UHP treatment in acetylation reaction might influence the physicochemical properties of starch acetate by facilitating the formation of lipid-complexed amylose or altering granular reaction patterns to acetic anhydride.