The effect of different concentrations of starter and ziziphora essence on physicochemical and microbial properties of doogh produced from sheep's milk

Doogh is a kind of fermented milk, which is produced with different flavor, in this study; doogh was produced by sheep's milk containing different concentrations of starter and ziziphora essence. Five treatments prepared by two concentrations of starter (0.0125%, 0.025 %) and two concentrations of ziziphora essence (0.01%, 0.005%) and then physicochemical and microbial properties were studied during 1, 11 and 21 days of storage. Result showed that pH of all samples decreased, parallel to pH, acidity (Dornic) increased. The percentages of dry matter and sedimentation of all treatments increased during 21 days of storage period. Enumeration of Streptococcus thermophilus and Lactobacillus bulgaricus as a stater culture showed that bacterial count decreased during 21 days of storage. Totally with due attention of mentioned results, treatment C (0.025% starter+0.005% ziziphora essence) was the best among others.