Calcium Chloride (CaCl2) is frequently added to milk at the start of cheese making as a coagulation aid. This article discusses calcium’s role in mik and coagulation, and properties, availability, and storage of Calcium Chloride.
Calcium & Milk
Milk can have different rennet coagulation abilities and this can be caused mainly by different particle sizes of casein, the main protein in milk. The higher the milk’s content of calcium, the bigger the casein particles will be. The bigger the particles are, the better the coagulation ability of the milk. Secondarily, casein particle size also influences the ease by which cheese curds shrink and releases whey. If the casein particle size is big, the network is open and coarse, and whey drains more readily.
Different factors influence the calcium content of milk:
- Milk that is stored at low temperatures releases calcium. Thus the pasteurization process of heating and then rapidly cooling milk reduces calcium.
- Late lactation season milk has low calcium.
- Milk from diseased animals has low calcium.
To compensate for precipitation of calcium, calcium chloride is frequently added to milk as it is effective, low cost, and has long shelf life.
Calcium Chloride (chemical formula CaCl2) is a salt compound of one calcium and two chloride atoms. It is highly soluble in water and is a deliquescent meaning that in dry form it has a strong affinity for moisture and if left unsealed, will absorb large amounts from the atmosphere and will in time form a liquid solution. CaCl2 is a common additive in the food making industry. Common uses are for salty taste in sports drinks, as a preservative and to maintain firmness in canned vegetables, especially pickles, and in cheese making primarily when using processed – pasteurized milk.
Calcium Chloride Availability
Food grade Calcium Chloride is available from Cheese Making Supply Stores in solution format. It is also available in highly refined form for use in salt water aquariums, but it is not known if those products are human food grade quality.
Note, if the salt (NaCl) content in the milk is too high, ion exchange occurs, so that the calcium is displaced from casein by sodium, which to some extent decreases the milks’ coagulation ability. This is normally not a problem as salt is not normally added to cheese until after rennet coagulation.
Calcium Chloride Storage
In it’s crystaline dry form it should be stored in a dry location where as highly inert it can be kept indefinitely.
In it’s aqueous form it is still enert and requires no special storage.