Lactase is a purified liquid preparation of lactose, isolated from the lactic yeast Kluyveromyces lactis.

Lactase hydrolyzes lactose into glucose and galactose. The reaction rate depends on the temperature, the pH, the lactose concentration and the dose of the enzyme. Its optimum performance is obtained under conditions of pH (6.3 - 6.7) and temperature (35 - 40 C) very close to natural conditions since the lactase itself is a derivative of a milk yeast. However, lactase is also active at low temperatures of up to 4 C, which allows treatment to continue during night storage.

Milk thus hydrolyzed, with low lactose content, is more easily assimilated since lactose can only be absorbed by the organism if it has previously been transformed into glucose and galactose. Thus, a large part of the world population, which is lactose intolerant, can benefit from the almost perfect food that nature offers us: milk.

Lactase has also found numerous applications in the treatment of whey. The hydrolysed whey find more and more applications in human and animal food.