Lactase (b-D-galactosidase; b-D-galactoside galactohydrolase, E.C.
3.2.1.23) is widely distributed in nature and can be isolated from
different sources such as plants (almonds, peaches, apricots, apples),
animal organs, yeasts, bacteria and fungi (Richmond, Gray, & Stine,
1981). Lactases were first proposed for dairy applications in 1950
(Van Dam, Revallier-Warffemius, & Van Dam-Schermerhorn, 1950).
Lactose-hydrolysed milk and dairy products have been under devel-
opment since the 1970s, when the first b-galactosidases became
commercially available. Nowadays lactase is one of the most impor-
tant enzymes used in food processing (Panesar, Panesar, Singh,
Kennedy, & Kumar, 2006).