Calcium Chloride is useful in cheese making if you are using pasteurised milk. It helps to boost the level of calcium that may have been lost in pasteurisation. This is also particularly helpful if you are using vegetarian rennet and can produce a firmer curd. This 33% solution is used in the production of a wide range of cheeses, including Gouda, Cheddar and Feta. The addition of this solution (E509) to the milk ensures constant coagulation times for curd formation and it also improves the curd yield. Calcium Chloride has a very long shelf life