QUALITY OF YOGURT BLENDED WITH THYMUS KOTSCHYANUS ESSENTIAL OIL

In agreement with the current trend of giving value to natural and renewable resources, the use ofnatural antimicrobial compounds, particularly in food and biomedical applications, becomes very frequent. Thebehaviour of Listeria monocytogenes during the cold storage (10 days) of yoghurt which was produced withThymus Kotschyanus essential oil (0, 50, 150 and 300 ppm EO) with sensory attributes of yoghurt wereinvestigated, in addition, The viability of starter culture bacteria were studied. Viable counts of L. monocytogenesfall was sharp from 3.00 to 1.07 (log cfu/g) at the first day and was not present at the other storage day in yoghurtwith 300 ppm EO. In spite of L. monocytogenes could be isolated and counted in days 7 from control sample (1.19log cfu/g). Yoghurt made with 150 ppm of the EO had the highest starter culture bacteria count at the end of storage.Considering the organoleptic effect of the EO, the best treatment with acceptable flavor, good appearance wasobtained at 50 ppm EO. In conclusion, the combination of T. Kotschyanus EO treatment and other naturalpreservative was significantly effective in the inactivation of foodborne pathogens while maintaining acceptableyoghurt quality.Keywords: Yoghurt, Thymus kotschyanus EO, Listeria monocytogenes