Characteristics of Milk Thistle Seed Oil Extracted by Folch’s Extraction Procedure

Milk thistle (Silybum marianum L. Gaertn) is a medicinal plant from the family Asteraceae. Its seeds are renowned for their medicinal and industrial potential due to the presence of bioactive compounds, including silymarin and unsaturated fatty acids, vitamin E, flavonoids and phenolics, so it can be used in the prevention of cardiovascular disease.

In this study, Folch’s method was employed to isolate lipids from other components. The composition of fatty acids in the extracted oil was determined by gas chromatography (GC), and the thermal properties of the oil were examined by Pressure Differential Scanning Calorimetry (PDSC). Furthermore, the quality of the extracted oil was assessed through acid value and peroxide value tests. Additionally, the potential health-promoting properties of the oil were determined by measuring the total polyphenol content and antioxidant activity.

The results showed that predominant unsaturated fatty acids were linoleic acid (C18:2) and oleic acid (C18:1). Saturated fatty acids, such as palmitic acid (C16:0) and stearic acid (C18:0), also had a significant contribution. The distribution of fatty acids in triacyglycerols revealed that unsaturated fatty acids are often in the internal position (sn-2), while saturated fatty acids are in the external position (sn-1,3). The oxidative stability demonstrated that the extracted oil possessed a long oxidation induction time (47.62 min), which is comparatively higher than the oil extracted by the Soxhlet method. This could be associated with the non-use of heat in the Folch method. Both acid value and peroxide value were in permissible levels, which indicates that fresh seeds were employed without heating treatments. The total phenolic content analysis showed a minor presence of phenolic compounds.

In conclusion, the use of non-thermal extraction methods like Folch’s can effectively preserve the quality of the oil, making it a superior choice for health and nutrition applications.