PREPARATION OF WHEY-PROTEIN CONCENTRATE FROM SALTED WHEY AND ITS USE IN YOGURT

Salted whey (7-8% NaCl) was concentrated by ultrafiltration by a factor of 20. Sweet whey equal to the retentate volume was added and ultrafiltration was continued to a concentration factor of 20. Addition of sweet whey and ultrafiltration was repeated twice more for almost complete removal of salt from whey protein concentrate (WPC). The protein content of WPC was adjusted to 3.5% using sweet whey and the mixture was heated to 65-degrees-C for 30 min. This was mixed with buffalo milk at the rate of 0, 10, 20 or 30% and then heated at 80-degrees-C for 1, 5 or 20 min before use for yogurt manufacture. The chemical, rheological and organoleptic properties of the yogurt were investigated. WPC could be added to buffalo milk at up to 20% without affecting the quality of the yogurt produced. On the contrary, it improved the texture, mouthfeel and wheying-off of yogurt from buffalo milk. Yogurt with 30% WPC had an unacceptably weak body and texture for a set product. Heating at 80-degrees-C for 5 min was sufficient to produce good quality yogurt from buffalo milk containing WPC.