In general, water-soluble vitamins and minerals are lost into the cooking water, the amount depending on the surface area to volume ratio, i.e. greater losses take place from finely cut or minced foods. Fat-soluble vitamins are little affected except at frying temperatures. Proteins suffer reduction of available lysine when they are heated in the presence of reducing substances, and further loss under extreme conditions of temperature. Dry heat, as in baking, results in some loss of vitamin B1 and available lysine. The most sensitive nutrient by far is vitamin C, with vitamin B1 next. Average losses from cereals are: boiling, 40% vitamins B1, B2, B6, niacin, biotin, and pantothenic acid; 50% total folate; baking, 5% niacin, 15% vitamin B2; 25% vitamins B1, B6, and pantothenic acid; 50% folate; with biotin being stable. In meat, losses are approximately 20% of all the vitamins for roasting, frying, and grilling and 20–60% for stewing and boiling.
Subjects: Medicine and Health.