Effect of domestic cooking on the red cabbage hydrophilic antioxidants

The contents of vitamin C, total phenolics, anthocyanins, hydroxybenzoic and hydroxycinnamic acids as well as 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) monocation radical scavenging activity were evaluated in two varieties of red cabbage before and after conventional and steam-cooking. During the conventional cooking 32.7-64.5% of vitamin C and 45.7-66.9% of total phenolics were retained in cooked tissue. Decreasing cooking water volume by half led to better retention of both phenolics (by 2.7-14.5%) and vitamin C (by 14.2-18.4%). However, shortening the cooking time by half affected the retention of phenolics and vitamin C only by 3.8-6.7% and 0-2.2%, respectively. Steam-cooking is recommended to prevent the major loss of scavenging activity, because under these conditions, the corresponding TEAC (Trolox Equivalent Antioxidant Capacity) values were reduced only by 5-20%. Moreover, the content of vitamin C was decreased by 2.1-22.7% while losses of total phenolics were up to 10%. The phenolics are the major source of free radical scavenging activity of red cabbage, since the contribution of vitamin C to TEAC for fresh and cooked red cabbage was from 18.2 to 28.5%.