Low Temperature Lactose Hydrolysis of Concentrated Whey Permeates

Whey permeates containing 5, 15, and 25% lactose were hydrolyzed at 4°C with /J-D-galactosidase.The 15 and 25% lactose permeates were partly demineralized.Approximately 75 to 90% lactose hydrolysis occurred in 48 h at 4°C and 60 to 70% in 24 h at 4°C.Lowest hydrolysis was with 25% lactose permeates.Demineralization attained at 220 ohmcm compared with 160 ohm-cm coincided with decreased lactace activity; but enzyme reactivation occurred when potassium + ions were added to adjust pH to 6.8.