Whey, or lactoserum, is the residual liquid that results from the coagulation process of milk during its transformation into cheese. It is equivalent to what remains of the 2.64 gals (10 liters) of milk needed to produce 2.2 lbs (1 kg) of cheese. Although made at 90 % of water, whey is rich in soluble nutrients such as lactose, complete proteins, essential amino acids, vitamin B, or calcium.