Studies of alpha-tocopherol in UHT processed milk suggest that the processing conditions affect the subsequent losses, but that in all cases increased storage temperature led to increased rate of loss.
There was a loss of tocopherol reported in the study of potato chips. After only two weeks’ storage of the chips at room temperature, nearly half of the tocopherol was lost.
The losses were only slightly smaller during storage at freezer temperature.
Deep fat frying of fresh vegetable oil causes losses of about 10% but storage of fried foods, even at low temperature, may cause large losses. The low content of alpha-tocopherol in frozen foods is surprising and indicates serious degradation even at 12 °C.
Boling of vegetables in water for up 30 minutes results in only minor losses of tocopherol.
Baking of white bread (200 °C, 30 minutes) destroyed of about 5% of the tocopherol in the crumb.
Tocopherol losses during microwave cooking are mainly caused by the effect of high temperature and not by microwaves as such. When sunflower oil was subjected to microwaves discontinuously for 120 min at two constant temperatures: namely 170 °C and less than 40 °C, tocopherol losses were 72% and 21%, respectively.
Losses of tocopherol during food processing
