Investigating the essential oil of the medicinal plant Thymus (Thymus vulgaris L.) in the production of probiotic dairy products by determining the viability of bacteria

The purpose of the present study was to investigate the essential oil of the medicinal plant Thymus vulgaris L. in the production of probiotic dairy products by determining the viability.

Thyme essential oil is used as a flavoring agent in the production of traditional and industrial dairy products (yogurt, buttermilk, and curd). To produce probiotic products and pasteurized dairy products, bacteria are inoculated and different concentrations of thyme essential oil (0, 25, 40, 70, 100 and 130 micrograms/ liter) are added to dairy products. The viability of bacteria in dairy products is checked at specific time intervals (0, 4, 8, 12 and 20 days).

By increasing the concentration of thyme in traditional and industrial dairy products, there is a significant decrease in the logarithm of Lactobacillus and Bifidobacterium bacteria (P<0.05). The highest viability of bacteria was observed with low concentrations of thyme in traditional yogurt, and with moderate amounts of essential oil in buttermilk and traditional curd, within 20 days. The highest viability of bacteria is in yogurt and industrial butter with high concentration and in industrial curd with a decrease in the amount of essential oil. The highest viability of Bifidobacterium bacteria is found with high concentrations of thyme in yogurt, buttermilk and traditional curd (P<0.05), also with low concentrations of thyme in industrial yogurt and buttermilk, and with high concentrations in industrial curd.

In industrial dairy products with thyme, the viability of Bifidobacterium bacteria is longer, and in traditional dairy products, the shelf life of Lactobacillus bacteria is longer.