Impact of Mild Oven Cooking Treatments on Carotenoids and Tocopherols of Cheddar and Depurple Cauliflower (Brassica oleracea L. var. botrytis)

The effect of steam and sous-vide oven procedures on liposoluble antioxidants of colored cauliflower (orange and purple) was assessed for the first time and compared with domestic practice (boiling). In raw samples, the total carotenoid content was 10-fold higher in Cheddar than in Depurple (20.9 +/- 2.1 vs. 2.3 +/- 0.5 mg/kg dry weight), whereas the level of tocopherols was similar (28.5 +/- 4.4 vs. 33 +/- 5.2 mg/kg dry weight). The Cheddar liposoluble antioxidant matter contained violaxanthin, neoxanthin, alpha-carotene and delta-tocopherol, not detected in Depurple. All tests increased the bioactive compounds extractability with steam oven and sous-vide displaying similar effects, lower than boiling. In boiled Cheddar cauliflower, the total carotenoids and tocopherols contents increased with cooking time until they were 13-fold and 6-fold more than in raw cauliflower, respectively. Conversely, in the Depurple variety, contents increased by half with respect to the orange variety. However, from a nutritional point of view, no differences were revealed among the three different cooking treatments in terms of vitamin A and E levels expressed in mu g/100 g of fresh vegetable because of the higher water content of boiled samples that must be considered when evaluating the effect of thermal treatment on cauliflower nutritional traits.