Starch modification with phenolics: methods, physicochemical property alteration, and mechanisms of glycaemic control

Background: Reduced postprandial blood glucose levels are beneficial for chronic diseases, such as type 2 diabetes and obesity. However, cooking native starches make them easily digestible, leading to a high peak of postprandial blood glucose level. Starch modification is widely used in reducing starch digestibility. Dietary phenolics, such as polyphenols and phenolic acids, have been reported to possess antidiabetic and anti-obesity activities. The interactions between starch and phenolics have been gradually revealed. Thus, using phenolics to modify starch and improve the quality of native starches has become increasingly popular. Scope and approach: In this review, the different methods used in starch modification with phenolics were investigated. Changes in the properties of starch structure and digestibility were also discussed. The glycaemic control effect and its mechanisms were proposed. Possible future research focusing on the improvement of the modification methods and the understanding of the health benefits of modified starch was suggested. Key findings and conclusions: Physical, chemical and enzymatic modification methods have been used in starch modification with phenolics. Physical modification methods, including pre-gelatinisation and non-thermal food processing technologies are the most commonly used methods. Phenolics usually form starch-phenolic complexes in the modified starch. Chemical and enzymatic modification methods are used to synthesise phenolic starch esters. Modified starches were reported to have decreased digestibility and altered starch aggregation structure. Moreover, they possess a slight glycaemic control effect and more in-vivo studies are needed. The potential mechanisms of this effect include inhibition of starch digestion and glucose transport, promotion of insulin secretion and sensitivity, activation of AMPK and appetite control.