Effect of fermented dairy products on physicochemical and probiotic properties of tarhana in an in vitro gastrointestinal system

Abstract

Tarhana is a fermented food that holds an important place in traditional Turkish cuisine. This study aimed to produce tarhana samples with increased probiotic content using various fermented dairy products, including yogurt, probiotic yogurt, and kefir. These samples were evaluated for their physicochemical, microbiological, antioxidant, and in vitro digestibility parameters. Significant differences were observed among the tarhana samples in terms of their physicochemical and microbiological characteristics (p < 0.05). The probiotic yogurt group exhibited the highest protein content, whereas kefir-based samples showed higher mineral content and a more neutral pH value. Although antioxidant activity and total phenolic content varied among groups, the highest values were obtained in the probiotic yogurt samples. During fermentation, a significant increase in Lactobacillus (p = 0.011) and Lactococcus (p = 0.006) counts was observed in the probiotic yogurt group, while no significant changes were detected in the other groups (p > 0.05). Throughout simulated digestion, differences in bacterial viability among groups were not statistically significant (p > 0.05), although the yogurt group maintained comparatively higher overall survival rates. The findings reveal that tarhana samples prepared using different fermented dairy products exhibited significant differences in terms of microbiological quality and nutritional content.