The importance of ultrahigh pressure processing over the quality of the extracted oil from peony seeds (Paeonia suffruticosa Andr.)

- Extraction by atmospheric pressure led to the absence of linolenic acid in peony seeds oil.
- Extraction by 350 MPa led to the highest fatty acids number and fat acidity among all the oils.
- Oil extracted by 500 MPa had the highest unsaturated fatty acids content and the lowest fatty acidity.
- UHP is preferable to extract value-added oil in terms of yield and, in particular the quality.

The influence of extraction pressure on peony seeds (Paeonia suffruticosa Andr.) oil yield and quality was investigated using GC-MS, and the results indicated that the extraction of peony seeds oil under atmospheric pressure had the lowest oil yield and led to the absence of 9,12,15-octadecatrienoic acid in the oil. Ultrahigh pressure (UHP) of 350, 400, 450, 500 and 550 MPa was used in this study and the analysis demonstrated that all the extracted peony seeds oils using UHP technology had the common compounds including hexadecanoic acid, 9,12-octadecadienoic acid, 9,12,15-octadecatrienoic acid, and octadecanoic acid, but their proportions in the extracted oils greatly differed. Although the oil yield was the highest, the extraction at a lower pressure of 350 MPa achieved the greatest saturated fatty acids content of 49.49% and also the highest fatty acids number of 11, which might be due to the activated enzymes during the extraction. In contrast, the unsaturated fatty acids content in the extracted oil was up to be the highest of 87.57% when the extraction pressure of 500 MPa was used, and its corresponding fat acidity was found to the lowest level of 3.5 mg 100 g−1 among all the extracted oils. This study suggests that the both oil yield and, in particular the oil quality are greatly sensitive to the extraction pressure.