β-Galactosidases

Enzymes classified as EC 3.2.1.23, universally known as lactases, that hydrolyse lactose into glucose and galactose. They are the basis of the lactose-free dairy industry: treatment of milk with β-galactosidase breaks down the lactose that intolerant consumers cannot digest, producing milk that tastes slightly sweeter because glucose and galactose taste sweeter than lactose. They are also sold as digestive-aid tablets taken with dairy foods. In cheese and yoghurt manufacture, residual lactose hydrolysis prevents sandiness from lactose crystallisation. Fungal, yeast, and bacterial lactases differ in pH optima and are chosen to suit milk, whey, or acidic applications. They are among the most commercially successful food enzymes.