Effect of Cooking Upon the Thiamin Content of Foods

Abstract
Thiamin losses due to different cooking procedures were determined by the rat-growth method for a representative variety of foods. Experiments were set up to show the percentage of the thiamin originally present in the raw food that was (1) retained by the cooked product, (2) dissolved in the cooking water, and (3) destroyed. Thiamin destruction amounted to as much as 22% in some vegetables boiled in water and additional amounts up to 15% dissolved in the cooking water. In cases where the cooking water is discarded total thiamin losses in vegetables may amount to approximately 20 to 35%. The addition of a small amount of sodium bicarbonate markedly increased the destruction of thiamin in green peas and snap beans but had no significant effect upon the thiamin content of boiled navy beans. Roasting caused a loss of 43% of the thiamin in pork loin, nearly three times as much destruction as braising. Double boiler cooking of whole grain cereals did not destroy thiamin; baking bread caused about 15% loss of this vitamin. The relative values of the different cooked foods in meeting the daily human requirements for thiamin are discussed.