Solvent and enzyme-aided aqueous extraction of goldenberry (Physalis peruviana L.) pomace oil: impact of processing on composition and quality of oil and meal

Goldenberry pomace (seeds and skins) represent the waste obtained during juice processing (ca. 27.4\% of fruit weight). In the present contribution, the potential of goldenberry pomace for use as a substrate for the production of edible oil was evaluated. Toward developing goldenberry as a commercial crop, the results provide important data for the industrial application of goldenberry. Three extraction methods were checked for the best oil yield. The n-hexane-extractable oil (expressed as SE) content of the raw by-products was estimated to be 19.3\%. Enzymatic treatment with pectinases and cellulases followed by centrifugation in aqueous system (expressed as EAE) or followed by solvent extraction (expressed as ESE) was also investigated for recovery of oil from pomace fruit. Enzymatic hydrolysis of pomace followed by extraction with n-hexane reduced the extraction time and enhanced oil extractability up to a maximum of ca. 7.60\%. Moreover, enzymation followed by solvent extraction increased the levels of protein, carbohydrates, fiber and ash in the remaining meal. The study covers also the chemical composition and some fractional properties of different pomace extracts (EAE, SE and ESE). Concerning the oil composition, there were relatively no changes noted in the fatty acid pattern of the oils extracted with different techniques. Slight alterations in the amounts of other fat-soluble bioactives (i.e., sterols, tocopherols and phenolics) were recorded. The different pomace oils obtained were tested for their radical scavenging activity toward the stable 1,1-diphenyl-2-picrylhydrazyl radical and their oxidative stability. Generally, the quality of solvent extracted oils (ESE and SE) manifested higher radical scavenging activity and oxidative stability than the enzyme-extracted oil (EAE). The levels of polar lipids, unsaponifiables, peroxides and phenolics in different extracts were associated with oxidative stability and radical scavenging activity.