APPLICATION OF REVERSE-OSMOSIS FOR CONCENTRATION OF BUFFALO MILK

Buffalo milk was concentrated to 1.5X (25% TS) and 2.OX (33% TS) levels employing reverse osmosis process and the changes in its physico-chemical, microbial and sensory properties were examined. The average permeate flux was 30.4 and 23.8 l/m2-h for 1.5X and 2.OX, respectively. The lipids, proteins, minerals and lactose in concentrated milk increased by the same level as the concentration factor, thereby indicating their 100% rejection by the thin film composite reverse osmosis membrane. There were no milk solids in the permeate at any stage of operation. The reverse osmosis process did not exert any adverse effect on the titratable acidity, pH, free fatty acids, free fat and microbial load. The sensory quality of reverse osmosis processed milk was not different from that of fresh buffalo milk. The most notable effect of reverse osmosis process was noticed on the size of fat globules, which reduced to less than 2.5mu upon 2.0X concentration. Consequently, the skimming efficiency of reverse osmosis milk was extremely poor.