Losses of tocopherol during food processing

Naturally occurring vitamin E comprises tocopherols and tocotrienols. Processing and storage of foods can result in substantial tocopherol losses. Cooking of porridges of rolled oats and rye meal implies only minor effects on their tocopherol and tocotrienols contents.

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 

Losses of nutrients during food processing

Some losses during in certain nutrients during food processing are inevitable.

The major consideration in evaluating food processing from nutritional stand point is that tradeoff between increase food availability and the effect that each of the various processing methods has on nutrients and food quality.

The degree of nutrient loss and the relative importance of the loss of a specific nutrient from a particular commodity should also be taken into consideration.

For example, vitamin C loss from milk during pasteurization and refrigerated storage is relatively unimportant, since it is insignificant source of this nutrient in the daily diet when compared with other foods as citrus fruits and juices.

The net effect of food processing on product quality is positive. The nutritive value of foods may be improved by increase in nutrient content and/ or digestibility of food component.

The aesthetic qualities of foods are also improved, resulting in enhanced appeal of the food to the appetite and better nutrient retention through consumption.
Losses of nutrients during food processing