Fermented goat milk enriched with milk thistle seed powder and its bioactive compounds: Chemical composition, color, texture, antioxidant activity, microbial quality, and volatile compound profile

Due to its superior antioxidant and anti-inflammatory properties, milk thistle has been widely used in various applications. In the present study, the effects of milk thistle seeds (MTS) powder and its ethanolic bioactive compounds extract on fermented goat milk were investigated. Fresh goat milk was enriched with 0.5%, 1%, and 2% of MTS powder and its extract, and the obtained product was analyzed after 1 and 14 d of cold storage. The MTS bioactive compound-ethanolic extract displayed higher antioxidant activities (DPPH•, ABTS•⁺, and ferric reducing antioxidant power) and total phenolic compounds compared with those extracted by using homogenization, ultrasonication, or microwave. The fatty acid composition analysis of MTS oil revealed that linoleic, oleic, palmitic, and stearic were the predominant fatty acids. The results also show that the addition of MTS significantly affected different yogurt characteristics. The MTS extract-enriched samples had higher moisture content than MTS powder-enriched and the control samples. Yogurt color, texture, and volatile compound profile were also influenced by the inclusion of MTS into yogurt formulation. The control yogurt samples displayed higher levels of 2,3-butanedione, 2-heptanone, 3-hydroxy-2-butanone, and 2-nonanone. In addition, MTS enhanced the antioxidant activities and microbial quality of goat milk yogurt.