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

The effect of steam and <i>sous-vide</i> 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 <i>Cheddar</i> than in <i>Depurple</i> (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 <i>Cheddar</i> liposoluble antioxidant matter contained violaxanthin, neoxanthin, α-carotene and δ-tocopherol, not detected in <i>Depurple</i>. All tests increased the bioactive compounds extractability with steam oven and <i>sous-vide</i> displaying similar effects, lower than boiling. In boiled <i>Cheddar</i> 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 <i>Depurple</i> 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 μg/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.