Skim Milk Fortification Using Blends of Skim Milk Ultrafiltrate and Cottage Cheese Whey

Permeate (pH 6.71) from ultrafiltration of skim milk was blended 1:1 and 2:1 (w/w) with whey (pH 4.68) resulting from production of cottage cheese from skim milk retentate. Blends were condensed to 50% solids and used to increase. solids concentration of skim milk by up to 2%. With increasing solids addition, skim milk pH declined and ash, lactose, and protein concentrates (wet weight basis) increased. The ratio of undenatured whey protein nitrogen:casein nitrogen increased by 50% in milk fortified with 2% added solids provided by condensed 2:1 permeate:whey blend. Bacteriological quality of fortified samples was satisfactory. Sensory evaluations indicated that skim milk fortification limits using 1:1 and 2:1 permeate:whey blends were 0.5 and 1.0% added solids, respectively.