A comparison of extraction yield, quality and thermal properties from Sapindus mukorossi seed oil between microwave assisted extraction and Soxhlet extraction

Abstract To improve the extraction efficiency and quality, microwave assisted extraction (MAE) method was proposed for separating oil from Sapindus mukorossi seed and compared with Soxhlet extraction (SE). The optimal condition of MAE obtained by Box-Behnken design was the mixed solvent of n-hexane and ethanol (4:1, v/v) as extraction solvent, microwave power 460 W, solvent to material ratio 8 mL/g, extraction temperature 72℃ and time 42 min. Under optimum conditions, the oil yield of 40.12 % was achieved, which was similar to that (40.63 %) of SE. All the oils shown similar fatty acid profiles, triglyceride profiles and thermal behavior. But the oil by MAE had better quality than that of SE, especially on low acid value and peroxide value. Additionally, solvent to material ratio, extraction time, energy consumption and carbon dioxide emission of MAE were lower than those of SE. It was shown from observation with a scanning electron microscopy that the structure of raw materials was destroyed by microwave treatment, which promoted the rapid extraction of oil. Overall, the results from this study suggest that MAE is an efficient and eco-benign method to extract oil from Sapindus mukorossi seed.