Production of functional probiotic goat yoghurt supplemented with black grape (Vitis labrusca L.) juice concentrate

Objective: To enhance the functional properties of yoghurt, one of the most preferred fermented milk products in Türkiye, black grape (Vitis labrusca L.) juice concentrate and the probiotic microorganism (Lactobacillus acidophilus) were added to goat milk yoghurt.Material and Methods: Goat milk yoghurt was prepared with varying concentrations of black grape juice concentrate, 0% v/v (Sample K), 0.5% v/v (Sample A), 1% v/v (Sample B), 1.5% v/v (Sample C) and 2% v/v (Sample D) While some properties (dry matter, oil, ash, protein) were analyzed only on the 1st day of storage, others (pH, titration acidity, antioxidant activity, phenolic compound concentration and microbiological properties) were evaluated on days 1,7,14, and 21 in samples containing black grape juice concentrate and probiotic bacteria.Results: When the antioxidant capacity values of the samples are compared, Sample B exhibited the highest value. Additionally, Sample D was found to have the highest phenolic content. The total phenolic content of the yoghurts, excluding Sample B, increased when comparing the 1st and 21st days of storage. It was also observed that yoghurts maintained their probiotic qualities throughout the storage period.Conclusion: The yoghurt samples successfully preserved their probiotic properties throughout the process. Additionally, it was determined that the black grape juice concentrate (Vitis labrusca L.) contained phenolic substances and exhibited antioxidant activity. As a result, a functional product with acceptable analysis was obtained.