Loss of vitamin content in food products because of vitamin instability; especially, in oxidation and during heating.

Methods of preserving foods add to the loss of vitamins. Pickling, salting, curing, or fermenting processes usually cause complete loss of vitamin C.

Commercial canning destroys frokm 50% to 85% of vitamin C contained in peas, lima beans, spinach, and asparagus. Pasteurization, unless special precautions are observed, causes a loss of from 30% to 60% of the vitamin C.