RENNET

a combination of two inorganic enzymes, or ferments—rennin and pepsin —obtained from the membranes of the stomachs of young mammals. The best quality is that from an animal so young that it has received no other food than milk—the rennin then predominating—and of this the most desired is from a calf’s stomach (its abomasum, or fourth stomach). After animals commence to eat other foods, pepsin predominates. Rennet’s chief importance from a food standpoint is its property of coagulating milk, and its widest food use is in the manufacture of cheese. Rennet extract is put up in liquid, powder, and tablet forms—the last-named popularly marketed as “junket tablets.’’: The first action of rennet on milk is to split up the casein and then to transform the whole volume of the milk into a ‘‘jelly.’’ This is the de ert phase (see JunKET). Later, the jelly develops into a separate, white, solid curd (chiefly of casein and fat with some water and a little sugar) and a straw-colored, liquid whey (chiefly water and the bulk of the sugar). This form also was once a popular dish, ‘‘eurds and whey,’’ and is one of the first stages of cheese-making (see CHEESE). The rennin of the human stomach is identical with that of the calf. Vegetable rennet is a similar ferment common in seeds during germination.