Effects of Dry and Wet Ultrafine Grinding on the Extraction Efficiency and Biological Activities of Polyphenols from Peach Pomace

In order to screen the ultrafine grinding methods which are conducive to polyphenol release and biological activity, the peach pomace was respectively treated by dry ultrafine grinding and wet ultrafine grinding, and then the polyphenol extraction, component identification and functional activity evaluation were carried out. The results showed that the content and purity of polyphenols increased by 23.3% and 25.6% respectively after wet ultrafine grinding compared with coarse grinding. The results of HPLC-MS identification showed that chlorogenic acid, D-(-)-quinic acid and catechins were the main polyphenols in the dry superfine grinding residue. However, benzoic acid, quercetin-3-β-D-glucoside and rutin were the main components in the wet superfine grinding residue. The results of antioxidant and anti-inflammatory activity evaluation showed that the peach pomace extract obtained by wet ultrafine grinding had better antioxidant activity (DPPH· and ABTS+· scavenging rate and total reducing power reached 80.16%, 47.07% and 1.112 respectively) and anti-inflammatory activity. In the study of α-glucosidase inhibitory activity, it was found that the polyphenols prepared by wet ultrafine grinding had higher inhibitory effect on α-glucosidase (80.22%), and based on the enzyme inhibition kinetics, it showed reversible competitive inhibition on α-glucosidase. Finally, in terms of antibacterial activity, the polyphenol extract prepared by wet ultrafine grinding had the strongest inhibitory effect on Staphylococcus aureus, Escherichia coli and Bacillus subtilis, and its minimum inhibitory concentrations were 3.13, 3.13 and 12.50 mg/mL, respectively. In conclusion, wet ultrafine grinding is more conducive to the efficient extraction of active polyphenols from peach pomace and its biological activity.