Glucosinolates, Carotenoids, and Vitamins E and K Variation from Selected Kale and Collard Cultivars

Glucosinolates, carotenoids, and fat-soluble vitamins E and K contents were analyzed from various kale and collard cultivars at mature stage. We found a significant difference in these phytonutrients among cultivars. Among kale cultivars, Beira and Olympic Red were the highest in the total glucosinolate and Toscano kale was the highest in total carotenoid content. Scarlet kale was highest in tocopherols. For collard, total glucosinolate was the highest in Top Bunch while carotenoids were the highest in Green Glaze. An accession PI261597 was the highest in phylloquinone. In addition to the total content of each phytonutrient class, their composition differed among cultivars, indicating that each cultivar may have differential regulatory mechanisms for biosynthesis of these phytonutrients. Our result indicates that cultivar selection may play an important role in consumption of kale and collard with greater nutritional benefit. Therefore, the result of this study will provide a more thorough profile of essential and nonessential phytonutrients of kale and collard cultivars for consumers' choice and for future research on nutritional value of these crops.