Optimization of extraction with the solvent method and physicochemical properties of pitaya seed oil

The Soxhlet extraction method was utilized to extract the oil from pitaya seed ( H.polyrhizus) .Single-factor tests were applied to study the effects of extraction solvent, drying time, solvent /material ratio, extraction temperature and time on the yield of pitaya seed oil.Then, response surface methodology ( RSM) was conducted to ascertain the optimum conditions for oil extraction. The physicochemical properties and fatty acid composition of the oil were analyzed. Results indicated that the optimal parameters of extraction were using petroleum ether as solvent, solvent /material ratio 7 ∶ 1 ( mL∶ g ) , extraction temperature 78℃, and time 3h. Under these conditions, the extraction yield was high up 31.47% ( v /w) .The acid value and peroxide value of the produced pitaya seed oil met a criterion for edible oils of nation. According to the results of the GC - MS analysis, the pitaya seed oil was composed of eight kinds of fatty acids.The contents of linoleic acid, oleic acid, palmitic acid and stearic acid were 47.98% , 28.13% , 16.77% and 5.02% , respectively. Calculating via the area normalization method, the unsaturated fatty acid accounted for 77.58% ( w /w) of the total amount of oil. Therefore, the pitaya seed oil was a kind of nutritional oil with a high development potential.