Optimization of Ultrasound-Assisted Extraction of Peony Seed Oil with Response Surface Methodology and Analysis of Fatty Acid

Optimized ultrasound-assisted extraction conditions (solid-to-liquid ratio of 1:7, ultrasonication time of 66 min, ultrasonication temperature of 55 degrees C and ultrasonication power of 395 W) were obtained by using response surface methodology to obtain the maximum oil yield from peony (Paeonia suffruticosa Andr.) seeds. The yield of extracted oil under optimized conditions from peony seeds in response to different harvest times ranged from 25.35 +/- 1.45% to 30.85 +/- 1.15% and reached a maximum 100 days after pollination (DAP). Analyses of fatty acid composition in peony seed oil by GC-MS showed that the relative contents of polyunsaturated fatty acids and alpha-linolenic acid were higher during the period from 95 to 105 DAP, exceeding 90% and 33% of total fatty acids, respectively, and the ratios of omega-6:omega-3 varied from 0.87:1 to 1.66:1. Moreover, the optimized extraction conditions and fatty acid characteristics of peony seed oil in different harvest time periods may be used as important references for the industrialization of peony and harvest time of peony seeds in the future.