Carotenoid Concentrations In Brassicaceae Sprouts Do Not Differ Among Genotypes

Vegetable crops marketed as sprouts are becoming increasing popular with health conscious consumers in the U.S.  Research conducted by scientists at John Hopkins University School of Medicine lead to the development of broccoli (Brassica oleracea var. italic) sprouts (BroccoSprouts^®) marketed based on their concentrations of the anticarcinogenic glucosinolate sulforaphane.  Vegetables from the Brassicaceae family are well known for their pungent flavors and high concentrations of antioxidant secondary metabolites.  Sprout blends of broccoli, clover (Trifolium L. species), mustard (B. juncea L.), radish (Raphanus sativus L.), and alfalfa (Medicago sativa L.) are now available.  What remains uncertain are the concentrations of other antioxidant secondary metabolites provided by Brassicaceae sprouts.  The goal of our project was to indentify and characterize carotenoid compounds present in sprout tissues of several Brassicaceae species and compare their values with BroccoSprouts.  We grew and evaluated sprouts of:  Brassica oleracea var. fimbriata ‘Dwarf Siberian Improved Kale’; broccoli (unknown cultivar); ‘Scarlet Globe’ radish; brown mustard (unknown cultivar); ‘Florida broadleaf’ mustard; and B. rapa var. rosularis spinach mustard (unknown cultivar).  Seeds of each species were sprouted on paper towels in propagation domes in a RCB design in a glasshouse in Knoxville, TN for 16 days before harvest.  BroccoSprouts were purchased locally.  Pigments present in the sprouts were extracted and measured for using HPLC methodology.  Across all genotypes, sprouts were found to have high concentrations of nutritionally important carotenoids (5.0, 0.6, and 2.3 mg/100 g fresh weight for lutein, zeaxanthin, and β-carotene, respectively).  However, results showed no differences among genotypes for violaxanthin, neoxanthin, lutein, zeaxanthin, β-carotene, chlorophyll a, or chlorophyll b pigments.  Only antheraxanthin demonstrated significant differenced among genotypes.  In general, radish sprouts had the highest concentrations of chlorophyll and carotenoid pigments.  Broccosprouts had the lowest concentrations of violaxanthin, antheraxanthin, zeaxanthin, β-carotene, and chlorophyll pigments.  Previous research in our group has demonstrated that mature vegetables of the Brassicaceae have significant genetic variation for leaf tissue pigment concentrations.  Results from this study have shown sprout tissue carotenoid concentrations can be high; however, carotenoid pigments remain at consistent levels in sprout tissues among different Brassicaceae vegetables.