How is cheese made?

Cheesemakers first add starter bacteria to milk, which turn lactose into lactic acid and help develop flavour. Rennet, an enzyme traditionally from calves’ stomachs but now often microbial, makes the milk proteins, called casein, clump into a soft gel. The curd is cut, stirred and heated to release whey, and the curds are drained, salted and pressed into moulds. Many cheeses are then aged for weeks to years, as bacteria, moulds and enzymes transform texture and taste. Differences in milk, bacteria, moulds and ageing produce the variety of cheeses.