Influence of Cold Plasma and Ultrasonication on the Extraction Efficiency and Quality of Oil from Milk Thistle Seeds (Silybum marianum L.)

The current study aimed to evaluate the impact of cold plasma (CP) treatment for durations of 10 and 15 min, as well as ultrasonication (UT) for 20 and 30 min on the oil extraction efficiency (OEE) from milk thistle seed (MTS). Additionally, the study focused on evaluating the quality parameters of the extracted oil, including Rancimat oxidative stability, acidity value (AV), peroxide value (PV), total phenolic content (TPC), and antioxidant activity. These parameters were assessed over storage durations of 1, 30, and 60 days at a temperature of 4 degrees C. The findings indicated that treating MTS with cold plasma (CP) and ultrasonic treatment (UT) significantly enhanced the OEE by up to 29% for 15 min of CP treatment and 24% for 30 min of UT. Moreover, these treatments resulted in a notable reduction in AV (49% for CP and 46% for UT) and PV (38% for CP and 35% for UT) after 60 days of storage. Furthermore, the oil extracted from treated MTS exhibited a higher total phenolic content (74% for CP and 66% for UT) and increased antioxidant activity (156% for CP and 127% for UT) compared to samples obtained without any treatment. Additionally, the application of CP for 15 min led to a significant increase in alpha-tocopherol content (by 157%), while UT for 30 min resulted in a reduction of alpha-tocopherol by 76%. The analysis of the fatty acid (FA) profile revealed that CP treatment for 15 min increased linolenic acid content by 2.8% and arachidonic acid by 35%, while simultaneously decreasing oleic acid by 1.66% and linoleic acid by 2.1%. In contrast, UT for 30 min resulted in an increase in linoleic acid by 0.27%, linolenic acid by 8%, and arachidonic acid by 41%, while reducing oleic acid content by 2% in the final oil samples. In conclusion, the results of this study suggest that the application of CP and UT significantly enhances both the oil extraction efficiency and the quality of the extracted oil, providing substantial economic and quality benefits for the industry.