V6a-amylose helical cavity and benzoic acids with para-hydroxyl structure facilitate the formation of inclusion complex

Abstract

Benzoic acids are always unstable during thermal processing. Herein, effects of typical molecular structure of benzoic acids and V-amylose on the formation and thermostability of inclusion complexes were investigated. Interestingly, the helical structure of six V-amylose transformed to V_6a-amylose after complexing with four benzoic acids. Encapsulation efficiency (EE) and loading efficiency (LE) results presented that gentisic acid (DA) complexed with V_6a-amylose achieving the highest EE of 79.76 % and LE of 7.25 %. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) results demonstrated that DA, protocatechuic acid (PA), and gallic acid (GA) formed VI inclusion complexes with V-amylose, especially V_6a-amylose-DA inclusion complexes with the highest crystallinity, while p-hydroxybenzoic acid (PHBA) was difficult to complex with V-amylose. Moreover, V_6a-amylose-DA inclusion complexes showed the highest capacity in protecting the antioxidant activity from thermal processing. This suggested both V_6a-amylose helical cavity and benzoic acids with para-hydroxyl structure facilitated the formation of thermostable inclusion complexes.

Keywords: Amylose helical structure; Benzoic acids; Structure; Thermal stability.