Chapter 13 Kale as a functional vegetable. Nutritional value, bioactive compounds and the influence of processing and cultivation

Abstract

Abstract Kale (Brassica oleracea var. acephala) is one of the most valuable leafy green veg- etables due to its high content of important phytonutrients. Recently, kale has attracted increasing attention from scientists as a functional product for health nutrition. This study summarizes current knowledge about the chemical composition of kale, focusing on glucosinolates, isothiocyanates, and phenolic compounds that exert antioxidant, anti-inflammatory, and chemoprotective effects. Particular attention is paid to the influence of biotic and controlled abiotic stresses on the accumulation of these compounds in plant tissues. The work also examines the influence of culinary and industrial processing technologies on the preservation and transformation of biologically active sub-stances in kale. It is summarized that heat treatment using water significantly re-duces the content of glucosinolates and phenols, while steaming, short-term frying, and freezing after blanching preserve these compounds better. Innovative non-thermal technologies, such as high hydrostatic pressure, also show potential to increase the conversion of glucosinolates to biologically active isothiocyanates. The results highlight the importance of optimized growing and processing con- ditions to stabilize the nutritional and functional value of kale products. Therefore, kale can be considered a promising raw material for the development of functional health products for the prevention of diet-related chronic diseases.