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

Moo Jung Kim,Kang-Mo Ku,Yu-Chun Chiu

doi:10.1155/2017/5123572

Abstract

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.

Highlights

Studies have reported inverse association between consumption of Brassica vegetables and the risk of cardiovascular disease and cancers, especially lung, stomach, colon, and rectal cancers due to the abundance of phytonutrients such as glucosinolates, carotenoids, and vitamins in Brassica vegetables [1,2,3]
Indole and total glucosinolate contents were significantly higher in collard than in kale while there was no significant difference in total aliphatic glucosinolates between these two crops
The total glucosinolate varied significantly within a crop, for instance, 0.66–8.03 μmole/g DW in kale. This result indicates that cultivar selection plays an important role in consuming kale with greater health-promoting values that are related to glucosinolates

Summary

Introduction

Studies have reported inverse association between consumption of Brassica vegetables and the risk of cardiovascular disease and cancers, especially lung, stomach, colon, and rectal cancers due to the abundance of phytonutrients such as glucosinolates, carotenoids, and vitamins in Brassica vegetables [1,2,3]. A study from Centers for Disease Control and Prevention reported collard and kale being ranked at 10th and 15th place of “powerhouse” fruits and vegetables [5]. Glucosinolates are sulfur-containing plant secondary metabolites that are present in Brassica crops. The profile of glucosinolates of kale has been shown to vary depending on crop, cultivar, maturity, or plant tissue [8, 9]. The glucosinolate profile in collard has only been reported relatively recently and there is a large variation in glucosinolate content, partially due to different cultivars investigated [10,11,12]

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