Valorization of peach (Prunus persica L.) peels and seeds using ultrasound and enzymatic methods

Abstract

This study focuses on the holistic valorization of the substantial by-products of peach processing, namely peels and seeds, which incur disposal cost and environmental concerns. Phenolic compounds were extracted from peach peels with ultrasound-assisted extraction after enzymatic pretreatment involving two enzymes, cellulase and pectinase, under varying conditions. The optimal extraction yield (2.376 mg GAE/g dry peach peel) was obtained after pretreatment for 150 min, with a water to peels ratio of 4 mL/g, an enzyme concentration of 3 %, and a cellulase-pectinase enzyme with a composition of 50 % cellulase and 50 % pectinase. This yield was higher than the maximum efficiency obtained through ultrasound-assisted extraction without enzymatic pretreatment (1.580 mg GAE/g dry peach peel). In addition, a technique for peach seeds valorization was developed by employing ultrasound-assisted extraction in order to extract seed oil. The highest efficiency (0.197 g oil/g dry seeds or 90 % oil recovery) was obtained at a temperature of 42.5 °C, a solvent-to-powder ratio of 16 mL/g, and an amplitude level of 45 % after 35 min. This efficiency was consistent with the yields obtained by other conventional extraction methods at much longer extraction times (4–18 h). The effect of both ultrasounds and enzymatic treatment was provided by SEM micrographs, which mainly showed how cell walls were affected in contrast to conventional extraction methods.