The impact of tarragon essential oil on the activity of starter bacteria, molds and yeasts and the improvement of the properties of traditional yogurt

The aim of this study was to increase the shelf life of traditional yogurt, to improve its consistency and to prevent whey syneresis by adding tarragon essential oil. Yogurt was produced by industrial procedures and then the essential oil was inoculated into yogurt in different concentrations (10, 25, 30 ppm). Samples were examined for water storage capacity and microbial evaluation during 3 weeks of storage at two temperatures (refrigerator temperature and room temperature). The results showed that different concentrations of tarragon, temperature and storage time had a significant effect (p <0.05) on water holding capacity as well as the number of starter bacteria, molds, and yeasts. Tarragon essential oil reduced the number of bacteria, molds, and yeasts that spoil yogurt. The final results showed that the use of tarragon was not effective in water retention of yogurt samples, but it affected the number of initiator bacteria and yeast. Yogurt samples with high concentration of tarragon had the highest score in terms of consistency and sour taste. While samples with low concentration of tarragon, in terms of yogurt taste, had the highest sensory score.