Effect of Homogenization of Milk on Physicochemical and Microbiological Properties of Kefir ABSTRACTIn this study, the physicochemical and microbiological characteristics of kefir produced from homogenized milk at four different pressures (15, 15/5, 30 and 30/5 MPa) in single-stage or two-stages were determined. Kefirs were stored at 4°C for 30 days. Dry matter, ash, fat and protein contents of samples were determined on the first day of storage while pH, titratable acidity and rheological and microbiological properties of samples were determined on the 1 st , 15 th and 30 th days of storage. Moreover, particle sizes were determined in milk homogenized at different pressures. With an increase in the homogenization pressure and stage, the D[4,3] (µm) and D[3,2] (µm) values of milk samples increased while their specific surface area values decreased. At the end of the storage period, pH, viscosity, thixotropy and consistency coefficient values, lactobacilli, lactococci, total mesophilic aerobic bacteria and yeast counts decreased in kefir samples. The highest viscosity, thixotropy and consistency coefficient values were determined in samples produced at 15 MPa in a single-stage, and the highest counts of lactobacillus, lactococcus and yeast were in samples produced with non-homogenized milk.