Abstract
Traditional Brassica crops are valuable sources of bioactive compounds and contribute to the preservation of agricultural biodiversity. This study compared the phytochemical composition of two Apulian Brassica landraces, ‘Cavolo riccio’ (Brassica oleracea var. acephala) and ‘Cima di rapa di febbraio’ (Brassica rapa subsp. sylvestris), and evaluated the effects of boiling and steaming on their nutritional quality. Samples were analyzed in raw, boiled, and steamed forms for dry matter, polyphenols, flavonoids, phytosterols, photosynthetic pigments, anthocyanins, and glucosinolates. The two landraces showed complementary phytochemical profiles. ‘Cavolo riccio’ contained higher levels of dry matter, polyphenols, chlorophylls, carotenoids, and anthocyanins, whereas ‘Cima di rapa di febbraio’ was characterized by a substantially higher glucosinolate content. Phytosterol concentrations were similar in both landraces, averaging about 7 mg 100 g⁻¹ FW. Cooking significantly affected most bioactive compounds. Boiling caused the greatest reductions in dry matter, phenolic compounds, pigments, and glucosinolates, whereas steaming generally ensured higher retention. Total polyphenols decreased by 59% after boiling, while total glucosinolate content declined from 95.6 to 25.9 μmol kg⁻¹ FW. In contrast, steamed samples largely preserved glucosinolates and polyphenols, although reductions in flavonoids, carotenoids, and anthocyanins were still observed. Phytosterols were unaffected by thermal processing. These findings highlight the nutritional complementarity of the two Brassica landraces and identify steaming as the most suitable cooking method for preserving their nutraceutical value while supporting the valorization of local vegetable biodiversity.