Abstract: The microwave-assisted extraction of oil from Rana chensinensis eggs using anhydrous ethanol as the extraction solvent was optimized by one-factor-at-a-time method and response surface methodology. With this aim, we investigated the effect of solid-to-solvent ratio, soaking time and microwave power on the oil yield. The results obtained from the study showed that the optimized conditions were as follows: solid-to-solvent ratio, 1:9.82 (g/mL); soaking time, 3.33 h; microwave irradiation time, 30 min; and microwave power, 600 W. Under these conditions, the oil yield could reach (20 ± 0.67)%, which was higher than that obtained by other extraction methods. By gas chromatography-mass spectrometry (GC-MS), 27 fatty acids in the extracted oil were detected. Unsaturated fatty acids accounted for 54.98% of the total fatty acids in the oil, with 9-octadecadienoic acid, cis-11,14-eicosadienoic acid, 7,11,14-eicosatrienoate, 8,11,14,17-eicosatetraenoate, 9,12,15-octadecatrienoic acid, 9-hexadecenoic acid and 7,10,13,16,19-docosapentaenoate being predominant.

Key words: Rana chensinensis egg oil, microwave-assisted extraction, extraction yield, response surface methodology, fatty acid composition