Preparation of edible starch nanomaterials for the separation of polyphenols from fruit pomace extract and determination of their adsorption properties

Apple polyphenols are abundantly present in apple pomace, and their applications are limited by the low efficiency of traditional extraction methods and the tendency to pollute the environment. Starch nanoparticles (SNPs) have received much attention due to their renewable, low cost and biocompatibility. The aim of this study was to prepare SNPs of different sizes from corn starch using ultrasonic-assisted chemical precipitation with adsorption of apple polyphenols, investigate the relationship between particle size and adsorption, while experiments were performed to assess antioxidant activity, simulate in vivo digestion and polyphenol release. The results showed that the smaller the particle size of SNPs the higher the adsorption of polyphenols, and the combination of characterization and adsorption kinetics showed that this adsorption was a physicochemical binding process. DPPH radical scavenging activity showed that polyphenols bound to SNPs were more stable than free polyphenols. In vitro simulation of digestion and release processes, SNPs loaded with polyphenols showed better anti-digestive properties, polyphenols are released in small amounts in gastric juices and continuously in intestinal juices. Our results provide a theoretical basis for the direct separation of polyphenols from fruit pomace polyphenol extracts using nanomaterials and the industrial utilization of polyphenol products.