Amidation pectin with high viscosity and enhanced gelation properties: Preparation, characterization and viscoelastic behaviors

The low viscosity and strict gelling conditions of pectin significantly limit its applications in the food and biomedical industries. To address these challenges, this study develops a novel alanine-modified pectin (Ala-Pe) through papain-catalyzed amidation under low-temperature conditions. Structural analysis confirmed the successful grafting of alanine, achieving a grafting rate of 13.51 %. This modification notably enhanced the viscoelastic and gelation properties of pectin, particularly under acidic conditions (pH 3) and high calcium ion concentrations. The modification induced conformational changes in pectin molecules, strengthened intermolecular interactions, and broadened its functional scope, overcoming the limitations of conventional high-ester and low-ester pectins. This study presents an eco-friendly, low-energy approach for synthesizing highperformance pectin derivatives and offers valuable insights into the structure-property relationships of amidated pectin.