Evaluation of physicochemical properties, antioxidant and sensory activity of three types of functional low-fat probiotic yogurt

Yogurt is one of the most popular dairy products that is widely consumed around the world, which has received much attention due to its high nutritional value and economic importance. Therefore, in this study, by considering different indicators, in order to improve the nutritional properties of yogurt and produce products with desirable and uniform quality, by adding essential oils to control acidity, prevent and cover the acidity over time and also achieving antioxidant properties.

In this study, after preparing probiotic yogurts containing saffron, thyme and black cumin essential oils at four levels (0, 0/5, 1 and 2), physicochemical properties (PH, acidity, color, hydration and viscosity) and sensory properties were studied in a completely randomized manner in three replications over 21 days.

The results of the evaluations of this study showed a significant effect of independent variables and also their synergistic effect at the level of 0.5% on the properties of yogurt. In the study of color parameters, it was observed that the brightness decreased with increasing the concentration of essential oil so that the control sample had a higher L* index, also a* and *b index increased with increasing essential oil concentration. The increase in b* index was more due to the presence of carotenoid pigments in saffron essential oil. The pH changes of yogurt treatments were completely affected by microbial growth in the treatments, which significantly reduced and increased the acidity over a period of 21 days (P ≤ 0.05).

Enrichment of probiotic yogurt formulated with essential oil can be a good option in improving the functional properties of the final product and enhancing its antioxidant   properties.