Physicochemical properties and structure of starch ester/copolymer/complex synthesized by combination of microwave and acid (anhydride): A review

Native starch has many functional disadvantages that limit its wide commercial application as a renewable biopolymer. Therefore, starch modification is needed. Esterification/compounding/polymerization modification of starch using microwave combined with acid (anhydride) (MCA) to introduce new groups and give new functional properties to the starch. In the process, the structural and physicochemical properties of the starch are changed. The study of changes in the structure and physicochemical properties of starch by MCA is particularly significant to guide the application of modified starches and to modify them more effectively. This review describes the changes in the structure and physicochemical properties of starch ester/copolymer/complex synthesized by MCA and the applications for which the relevant modified starches were obtained. Future directions for MCA modification are also discussed. The structure and physicochemical properties of the starch obtained after modification of the starch by MCA are mainly related to the degree of substitution (DS) of the modified starch and the type of acid (anhydride). The physicochemical properties and structural changes of the starch appear differently depending on the modification method. Most starch modifications show the same trends in the structural and physicochemical properties of the starch. The DS of the modified starch obtained after modification of the starch by MCA is low, so other techniques can be combined to increase the DS of the modified starch and obtain a suitable modified starch.