Enzymes in Cheese Production

Cheese is a dairy product made from the curdled or coagulated milk of various animals, most commonly cows, goats, or sheep. Enzymes are essential to its production: they influence coagulation, proteolysis, lipolysis and other biochemical processes that shape the final characteristics of different cheese varieties, including flavour and texture. Which enzymes are used, and how they act, depends on the type of cheese being produced, the desired flavours and textures, and the aging process used.

Coagulation is driven principally by rennet, which contains chymosin. Chymosin cleaves a specific bond in the casein molecule, causing it to aggregate and form curds. It can be sourced from animal rennet, typically from the stomachs of young calves, or produced using microbial fermentation techniques. Microbial rennet is the more common route for vegetarian-friendly cheeses. Pepsin, found in animal stomachs, is also used for coagulating milk proteins and works similarly to chymosin by breaking down casein proteins.

Beyond coagulation, proteases break proteins down into smaller peptides and amino acids and are often naturally present in milk or introduced through starter cultures. Lipases break down fats into fatty acids and glycerol by lipolysis. Lactase breaks down lactose, the sugar found in milk, and is used in some cheese production processes to reduce lactose content, which is beneficial for individuals with lactose intolerance.

Starter cultures contain specific strains of bacteria that ferment lactose into lactic acid, reducing the pH of the milk; this lower pH aids protein coagulation and curd formation. A range of secondary enzymes is also present in milk or introduced during cheese-making, and these can have subtle yet important effects on the cheese's characteristics.