Viability of Starter Bacteria and Anti-Oxidative Activity of a Functional Yogurt Containing Silybum marianum Seed Extract

Background and objective: Silybum marianum seed extract (silymarin) is rich in phenolic compounds with anti-oxidative activity that add beneficial and healthful properties to silymarin-enriched products. The present study investigated effects of silymarin on characteristics of a functional yogurt. Material and methods: In this study, yogurt was enriched with Silybum marianum seed extract at concentrations of 0, 25, 50 and 100 mg l^-1 milk and the samples were analyzed for physicochemical and sensory properties and viability of starter bacteria during 21 days at 4°C at 7-day intervals. Results and conclusion: Results showed that increasing silymarin proportion in yogurt samples increased anti-oxidative activity, total phenolic content, total viability of Lactobacillus delbrueckii and decreased pH value, viscosity and sensory attributes (p 0.05). Furthermore, pH, viscosity, anti-oxidative activity, phenolic compounds and sensory attributes decreased during storage (P 0.05). In conclusion, 25 mg Silybum marianum seed extract per one liter of milk can be used for the preparation of yogurts with healthy properties.