Characterization of modified starch-based complexes-stabilized linolenic acid emulsions and their enhanced oxidative stability in vitro gastrointestinal digestion

Abstract

A new approach of fabricating α-linolenic acid emulsions with enhanced oxidative stability in vitro digestion was established, using covalent octenyl succinic anhydride starch (OSAS)-soy protein (SP)-epigallocatechin-3-gallate (EGCG) complexes as emulsifiers. The physicochemical characteristics and surface morphology of emulsions were mainly characterized by rheological measurements, laser scanning microscope (CLSM) and cryo-scanning electron microscopy (Cryo-SEM). Results indicated that emulsions had dense interfacial layers and strong network structures. As a result, the stability and antioxidant ability of emulsions were improved significantly. In addition, the oxidative stability of emulsions in vitro gastrointestinal digestion was explored. Results showed that emulsions could maintain better oxidative stability owing to antioxidant activity of covalent OSAS-SP-EGCG complexes under gastrointestinal conditions. In particular, lipid hydroperoxide and malondialdehyde contents of emulsions prepared by 1:4 complexes were lower than 0.35 mmol/L and 20.5 nmol/mL, respectively, approximately half those of emulsions stabilized by OSAS (0.65 mmol/L and 39.5 nmol/mL). It was indicated that covalent OSAS-SP-EGCG complexes could effectively inhibit α-linolenic acid oxidation in emulsions during vitro gastrointestinal digestion. This work will provide a theoretical basis for the development of α-linolenic acid emulsions, which will help to broaden application of α-linolenic acid in food industry.