Effect of peanut shell pretreatment on aqueous enzymatic extraction of polyphenol-enriched peanut oil

Abstract

Peanut shells are widely recognized as a valuable source of natural polyphenols. To improve the quality of aqueous enzymatic peanut oil (AEPO), a polyphenol-rich AEPO was prepared by pretreating peanut shells by cell disruption technology and integrating them into the AEPO extraction process. The key process parameters were systematically optimized and the following conditions were identified as optimal: hemicellulase-cellulase-pectinase complex enzyme (1:1:1, w/w/w) at an enzyme dosage of 1 % (w/w), peanut shell addition of 7.5 % (w/w), solid-liquid ratio (peanut/water) of 1:4 (g/mL), enzymatic hydrolysis pH of 4.5, reaction temperature of 55 °C, and enzymatic hydrolysis time of 3h. Under these conditions, the polyphenol and resveratrol contents in the peanut oil (PO) increased significantly from 25.54 mg GAE/kg and 0.15 mg/kg to 169.84 mg GAE/kg and 1.73 mg/kg, corresponding to "5.5-fold" and "10.5-fold" enhancements, respectively. In addition, the yield of clear oil increased from 57.83 % without enzymes to 82.49 %. Furthermore, incorporating pretreated peanut shells during aqueous enzymatic extraction preserved oil quality while elevating the polyphenol content, thereby improving the nutritional profile and stability of PO.