Effect of steaming and sous vide processing on the total phenolic content, vitamin C and antioxidant potential of the genus Brassica

This study evaluated the effect of thermal processing on the antioxidant potential, vitamin C, and total phenolic content of various parts, including edible co-products, of several Brassica vegetables. Overall, no significant differences were observed in the lightness of the samples after thermal processing, although the greenness and h degrees values of the samples were affected (p < 0.05). Similar profiles were observed for the leaves, inflorescences, and stalks of the studied crucifers. The stalks of some varieties, including broccoli cv. Parthenon and kale cv. Crispa, showed higher vitamin C contents compared to that of their inflorescences (p < 0.05). Both steaming and sous-vide processing significantly reduced the vitamin C and total phenolic content of the crucifers studied (p < 0.05). The results demonstrated that Brassica co-products contain valuable and health-promoting substances that can be lost during thermal processing; this must be considered when calculating the dietary intake of these compounds from cooked vegetables. Industrial relevance: The results obtained herein suggest that Brassica stalks are as nutritious and healthy as the florets or leaves, which are more commonly consumed as part of our diet. In addition, this study demonstrates the potential of Brassica co-products as a resource for the extraction of antioxidant compounds and opens new commercial opportunities for their use beyond their current applications in the food industry. The results also highlight that these compounds are mostly lost during processing and that the processing conditions should be carefully optimized to minimize their degradation.