A Green Aqueous Extraction of Peanut Oil using Microwave and Demulsifier

Abstract

In this study, distilled water was used as a sustainable solvent for extracting oil from peanuts using a salt-aided microwave technique. Furthermore several critical parameters were considered to achieve an optimal oil yield result. The oil extraction yield was compared to that obtained by soxhlet (43%) with n-hexan. In aqueous salt-aided microwave extraction (ASME) method, NaCl and CaCl2 were considered to promote the oil-water demulsification. Accordance to the results, an oil extraction yield of 32.08% was obtained at optimum operating conditions including of the calcium chloride concentration of 0.4 M, water to sample ratio of 20 ml/g, leaching time of 120 min, microwave radiation time of 8 min and microwave power of 720 w. The GC analysis did not show significant differences between the fatty acids profile of the oil extracted through the ASME and the soxhlet extraction (SOXE) methods. In both the extraction methods oleic and linoleic acid were the dominant fatty acids in the peanut oil. Some of the physicochemical properties of the oil such as acid value, iodine value, peroxide value, density and refract index were considered that there were no considerable differences between the two methods, just the acid value of the extracted oil by the ASME method was slightly more than the SOXE method. Also, the research on the total phenolic content and antioxidant activity of the extracted oil showed slightly better results for the ASME method compared to the SOXE method. So the ASME method is a valid technique to obtain an extra green part of peanut oil to consume in the food industry.

Keywords

• peanut
• oil
• extraction
• water
• microwave
• demulsifier