The study of the effect of oregano essence and Gellan gum on quality and shelf life of non-carbonated heat treated Doogh

In present study, the effect of different levels of oregano essential oil (0, 250 and 500 ppm) and gellan gum (0, 0.25, 0.5 and 0.75%) on the physicochemical, microbial and sensory properties of doogh during 60 days of storage in refrigerator conditions. The results showed that gellan gum and oregano essential oil had no significant effect (p<0.05) on the chemical properties of doogh including acidity, pH, fat and dry matter. Adding gellan gum to doogh increased the viscosity and stability of Doogh. Oregano essential oil significantly increased (p<0.05) DPPH radical inhibition and reduced oxidation. The minimum inhibitory concentration and the minimum bactericidal concentration of oregano essential oil on Escherichia coli are 1.6 and 3.12 mg/ml, respectively, and for Staphylococcus aureus, 0.4 and 0.80 mg/ml, respectively. was reported. In terms of sensory characteristics, the use of oregano essential oil and gellan gum did not have a significant effect (p<0.05) on the color of doogh, but the essential oil improved the flavor of doogh, gellan gum improved the mouth feeling. The doogh containing 0.5% gellan gum and 250 ppm of oregano essential oil had more acceptability and stability in terms of sensory properties and was free of contamination, which was recognized as the best treatment.