renneting

Renneting is a crucial step in cheesemaking that involves the coagulation of milk. It is the process by which rennet, an enzyme or a complex of enzymes, is added to milk to curdle it, separating the solid curds from the liquid whey. Traditionally, rennet was derived from the stomach lining of young ruminant animals, such as calves, lambs, or kids, which contained chymosin, the primary enzyme responsible for coagulation. However, modern cheesemaking utilizes various forms of rennet, including animal rennet, microbial rennet (produced by fungi or bacteria), and vegetable rennet (extracted from plants like thistle or artichoke).

The renneting process is influenced by several factors, including the type and amount of rennet used, the temperature of the milk, and the milk's pH. When rennet is added to milk, the chymosin enzyme breaks down kappa-casein, a protein in milk that stabilizes the casein micelles. This destabilization causes the casein micelles to aggregate, forming a three-dimensional network that traps the fat and water, resulting in the formation of a gel-like curd. The time taken for coagulation can vary from a few minutes to several hours, depending on these conditions. The solidified curd is then cut and further processed to produce cheese. The effectiveness and type of rennet can subtly influence the flavor, texture, and aging characteristics of the final cheese product.