Insights into the multi-scale structural properties and digestibility of lotus seed starch-chlorogenic acid complexes prepared by microwave irradiation

By inspecting starch hierarchical structural evolution, this work explored how microwave irradiation tailored the digestion characteristics of lotus seed starch-chlorogenic acid mixtures. The results showed that after microwave treatment, the granular structure, short-range ordered structure, helical conformation, and lamellar structure of starch exhibited different degrees of disorganization. In this procedure, chlorogenic acid interacted with starch molecules to form lotus seed starch-chlorogenic acid complexes and participated in the reorganization of the matrixes of the starch substrate in three forms: V-type inclusion complex, non-inclusion complex, and simply physically entrapped. These structural changes, coupled with the inhibition of chlorogenic acid on carbohydrate hydrolyzing enzymes, contributed to the slowly digestible features of lotus seed starch-chlorogenic acid complexes. This study provided a basis for understanding the multi-scale structure-digestibility relationship of starchy foods rich in phenolic acids under microwave treatment.