Nearly all cheesemaking requires the use of a coagulant. Natural coagulant comes from unweaned calves and is called rennet. An alternative to veal rennet is microbial coagulant, which is derived from Mucor miehei and is often referred to as vegetable or vegetarian rennet. Coagulants are available in either liquid or tablet formats. Liquid coagulants must be refrigerated. Calcium chloride will boost the coagulation ability of your coagulant if you are using store-bought, highly pasteurized and/or homogenized milk. Liquid coagulants must be refrigerated and never frozen.