Adsorption mechanism of polyphenols onto starch nanoparticles and enhanced antioxidant activity under adverse conditions

Polyphenols have potent antioxidant capacities and may reduce chronic disease risk. However, they are sensitive to pH, temperature, and light, limiting their applications. This study developed a starch nanoparticle based nanocarrier on which to load four polyphenols: (+)-catechin, (−)-epicatechin, (−)-epigallocatechin-3-gallate, and proanthocyanidins. The adsorption kinetics, adsorption isotherms, loading amount, loading efficiency, antioxidant activities, and in vitro release of the loaded polyphenols were analysed. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity demonstrated loaded polyphenols were more stable than free polyphenols if exposed to ionic strength, heating, and ultraviolet radiation. In addition, low cytotoxicity and good biocompatibility were found as determined by methyl thiazolyl tetrazolium assay. In artificial gastric (pH 2.0) and intestinal (pH 7.0) juices, the polyphenols showed a sustained release. These findings could lead to food formulations based on SNPs as a carrier of polyphenols and other bioactive compounds.