Findings of nutrient retention studies

At the Max Rubner-Institute, we did undertake nutrient retention studies, mainly with baked vegetables (broccoli, red pepper, courgette and button mushrooms).

We baked the vegetables under different conditions several times in an oven. The homogenised raw and cooked vegetables were analysed for mostly vitamins.

Regarding the results, for most vitamins, the vitamin contents of the baked vegetables exceed the content of the raw vegetables by far – weight changes and asscoiated with this, a concentration of nutrients are taken into account by the consideration of yield factors. This phenomenon appeared more or less for all vitamins and the strongest for the broccoli results.

The underlying incomplete release of some vitamins, especially tocopherol and ß-carotin, from the cell matrix of raw vegetables was already mentioned by some authors. At the moment we conduct some experiments with freeze-drying of raw vegetables which seems to have an positive effect on the extraction rate.

Do you have experience with the incomplete extraction of vitamins from raw vegetables?

Do you have experience with other food matrices where the values of the raw foods exceed the values of the cooked ones?