Stability in foods
The losses of thiamin in cooking depend on several factors, such as type of food, method of preparation, temperature, length of cooking, and the acidity or alkalinity of the cooking medium. Research indicates that on the whole fresh vegetables retain thiamin well during cooking. From a trace to 15% is dissolved in the cooking water, and up to 22% may be destroyed by cooking. If the cooking water is discarded, thiamin losses may be from 20% to 35%.
In acid foods this vitamin is quite stable, but its activity is destroyed micilv bv sulfite, a fact which may explain the loss of thiamin in dried fruits, such as apricots and peaches treated with sulfur.
Thiamin is well retained in cereals, as they are generally cooked slowly and at a moderate temperature, and the cooking water is not discarded. Baked products lose about 15% of their original thiamin. Generally, the losses in cooking meat are greater than in cooking other foods, ranging from 25% to 50% of the raw value.
