Ultrasound-Assisted Extraction of Phenolics from Pear Pomace: Method Optimization, Phenolic Profile, and Antioxidant Capacity

Pear pomace, a major by-product of the juice processing, represents a valuable yet underexploited source of bioactive compounds. In this study, ultrasound-assisted extraction (UAE) was optimized using response surface methodology to enhance the recovery of phenolic compounds from pear pomace powder with aqueous ethanol as the extraction solvent. A Box-Behnken design was employed to evaluate the effects of ethanol concentration (40-80%), extraction time (30-90 min), and ultrasonic power (48-144 W) on total phenolic content and DPPH radical scavenging activity. The results demonstrated that the negative quadratic effect of ultrasonic power on phenolic extraction yield exhibited the highest level of statistical significance. Extraction using 40% ethanol for 64.45 min at a power intensity of 117.6 W enabled the optimal recovery of phenolic constituents, yielding 280.1 mg GAE/L in the extracts. Using HPLC, the study explored how variations in ethanol concentration and extraction time affect the phenolic composition of the extracts. Chlorogenic acid, rutin and epicatechin were found to be the major polyphenolic compounds. Overall, pear pomace demonstrated strong potential as a low-cost source of phenolic compounds, and the optimized UAE process proved to be an efficient and robust approach for maximizing phenolic recovery.