Comparative Evaluation of the Physicochemical, and Antioxidant Properties of Milk Thistle Seed Cake Oils Extracted via Soxhlet and Microwave-Assisted Methods

Milk thistle seed cake, a by-product of silymarin production, contains residual oil with valuable bioactive compounds. This study compared oils extracted using microwave-assisted extraction (MAE) and Soxhlet extraction. MAE produced higher yields and better preserved polyunsaturated fatty acids. It also generated oils with lower acid and peroxide values, higher total phenolic content, and greater antioxidant capacity. Oxidative stability evaluated by pressure differential scanning calorimetry (PDSC) showed longer induction times for MAE-derived oils, indicating improved resistance to oxidation. These trends are consistent with the shorter extraction times and reduced thermal exposure associated with MAE. Overall, MAE proved more effective for recovering high-quality oil from milk thistle seed cake, supporting its use as a valuable resource in waste-to-value applications.