The present study aims at determining the most convenient operating conditions for obtaining a dietary complement of high quality, in terms of nutrient content and rehydration capacity, from disposable leaves of the white cabbage. Different thermal treatments were used for dehydration. Previously, some samples were applied blanching and freezing. These technological treatments and pretreatments, applied at different stages of the productive process, were conducted in order to evaluate and compare their effect on the content of nutrients and substances to be preserved, which were present in the fresh leaves. Then, the dietary complements obtained were analyzed. Proximal composition, vitamin C content, phenols and antioxidant activity were determined. Results indicate that a microwave drying process at 200 W following a 2 min blanching at 96±2 ºC resulted in an antioxidant dietary complement with an energy value of 1415.76±25.84 kJ, showing interesting amounts of proteins, carbohydrates, crude fiber, lipids and ashes.