Abstract: Methods for processing acid whey, involving treating acid whey solution with ?-galactosidase and/or ?-galactosidase, at a pH of about 3.2 to about 5.2 for about 20 minutes to about 16 hours at about 20° C. to about 60° C. to produce an acid whey solution containing at least about 40% less lactose than the original acid whey solution, filtrating the tempered acid whey solution to form a retentate containing proteins and a permeate containing lactose and residual proteins, recovering lactose from the permeate, optionally drying the retentate to form acid whey powder, and optionally texturizing the acid whey powder.