Oil extractability from enzymatically treated goldenberry (Physalis peruviana L.) pomace: range of operational variables

Goldenberry pomace (seeds and skins) represents a large portion of the waste generated during juice processing (ca. 27.4\% of fruit weight). The potential of goldenberry agro-industrial wastes for use as raw material for production of edible oil was evaluated. Fruit pomace, contained 6.6\% moisture, 17.8\% protein, 3.10\% ash, 28.7\% crude fibre and 24.5\% carbohydrates. The n-hexane-extractable oil content of the raw by-products was estimated to be 19.3\%. Aqueous enzymatic extraction was investigated for recovery of oil from the fruit pomace. The most significant factors affecting extraction were enzyme concentration, the time of digestion with enzymes, substrate concentration in water and the particle size of substrate. A broad variation in oil recovery was obtained depending on the operational conditions during the enzyme-aided aqueous extraction. The optimum and economical values were those obtained for 4:0.02:1 water:enzyme:substrate ratio. Generally, enzymatic treatment increased the extraction yield. The more than 42\% yield by enzymation compared with the nearly 3\% yield in the control process (without enzyme) implies a significant increase in yield by about 92.8\%. In single-enzyme trials, cellulase EC gave the best yield. Although proteases slightly improve yield, the enhancement values are much lower than those obtained with Cellulase EC and Pektinace L40. Rapid increase in oil yield occurred as the enzyme concentration increased from 1 to 2 g/100 g substrate. Yield increased with dilution, but it began to fall when the substrate became more diluted. Moreover, extractability increased significantly when particle size reduced. Concerning the oil composition, there were no great changes in the fatty acid pattern of the oils extracted with different hydrolytic enzymes when compared with each other or to the solvent extracted oil. The main purpose of this study was to maximise the efficiency of the enzymatic treatment for oil recovery from goldenberry pomace. As a first step toward developing goldenberry as a commercial crop, the results provide important information for the industrial application of the fruit.