Introduction Carotenoid pigments protect photosynthetic structures by quenching excited triplet chlorophyll to dissipate excess energy (1) and binding singlet oxygen to inhibit oxidative damage (2). Examples of carotenoids include lutein and -carotene.

There is strong evidence of the nutritional and medicinal importance of the dietary carotenoids. Carotenoids exhibit both antioxidant and anticarcinogenic activity (3). Dietary intake of lutein, -carotene, and other carotenoids has been associated with reduced risk of lung cancer and chronic eye diseases, including cataract and age-related macular degeneration (4).

Green leafy vegetables are rich in dietary carotenoids, and kale (B. oleracea L. Acephala Group) and spinach (Spinacea oleracea L.) rank high in lutein and -carotene content. Kale and other Brassica have been identified to vary for carotenoid content (5,6). However, limited information exists on lutein variability, especially among kale.

The goal of this study was to assess the variability of lutein and -carotene accumulation among a broad range of kale and spinach varieties.

Carotenoid Variability Among Kale and Spinach Varieties Carotenoid Variability Among Kale and Spinach Varieties David Kopsell,1 Dean Kopsell,1 and Joanne Curran-Celentano2

1Department of Plant Biology, 2Department of Animal and Nutritional Sciences, The University of New Hampshire, Durham, NH

Project Summary Kale and spinach contain the dietary beneficial carotenoids lutein and -carotene, but limited information exists on carotenoid accumulation within these vegetables. Therefore, different varieties of kale and spinach were field-grown, side-by-side, under similar production conditions to assess carotenoid variability.

Twenty kale and thirteen spinach varieties were field-grown between 2001-2002 according to New England Cooperative Extension recommendations. Choice of kale variety and production year affected carotenoid accumulation. However, rank order of varieties for lutein and -carotene content did not change between 2001-2002. Variability was also identified among spinach varieties during the 2002 season.

Under similar growing conditions, choice of kale and spinach variety will influence carotenoid accumulation and this may affect the health benefits of consuming these leafy vegetable crops.

Plant Culture From June to August 2001and 2002, 20 kale and 13 spinach varieties were field-grown (lat. 4309’N) according to New

England Cooperative Extension guidelines for minor cole crops (7). Plants

were harvested when mature and freeze dried in preparation for carotenoid analysis.

Literature Cited (1) Frank, H.A.; Cogdell, R.J. Carotenoids in photosynthesis. Photochem. Photobiol.

1996, 63, 257-264.

(2) Tracewell, C.A.; Vrettos, J.S.; Bautista, J.A.; Frank, H.A.; Brudvig, G.W. Carotenoid photooxidation in photosystem II. Arch. Biochem. Biophysic. 2001, 385, 61-69.

(3) Balentine, D.A.; Albano, M.C.; Nair, M.G. Role of medicinal plants, herbs, and spices in protecting human health. Nutr. Rev. 1999, 57, S41-S45.

(4) Le Marchand, L.; Hankin, J.H.; Kolonel, L.N.; Beecher, G.R.; Wilkens, L.R.; Zhao, L.P. Intake of specific carotenoids and lung cancer risk. Cancer Epidemiol. Biomarkers Prev. 1993, 2, 183-187.

(5) Mercandante, A.Z.; Rodriguez-Amaya, D.B. Carotenoid composition of a leafy vegetable in relation to some agricultural variables. J. Agr. Food Chem. 1991, 39:1094-1097.

(6) Kurilich, A.C.; Tsau, G.J.; Brown, A.; Howard, L.; Klein, B.P.; Jeffery, E.H.; Kushad, M.; Walig, M.A.; Juvik, J.A. Carotene, tocopherol, and ascorbate in subspecies of Brassica oleracea. J. Agr. Food Chem. 1999, 47:1576-1582.

(7) Howell, J.C.; Bonnano, A.R.; Boucher, T.J.; Ferro, D.N.; Wick, R.L. (eds.). Broccoli, cabbage, cauliflower, and minor cole crops, p. 64-70. In: 2002-2003 New England Vegetable Management Guide. UMass Ext. Offic. Commun. Mktg.

(8) Khachik, F.; Beecher, G.R.; Whittaker, N.F. Separation, identification, and quantification of the major carotenoid and chlorophyll constituents in extracts of several green vegetables by liquid chromatography. J. Agr. Food Chem. 1986, 34, 603-616.

AcknowledgementsThis project was funded in part by the Cooperative State Research, Education, and Extension Service, U.S. Department of Agriculture, under agreement No. 2001-52102-11254. The authors wish to thank the Northeastern Regional PI Station, USDA-ARS Plant Genetic Resources Unit, Cornell University, Geneva, NY for providing seed and John McLean, Evan Ford, and the UNH Woodman Horticultural Farm for their technical support of this research.

Conclusions 

Choice of both kale and spinach variety greatly influenced carotenoid accumulation under similar production conditions. Year of production also affected carotenoid levels among kale varieties. However, rank order of kale varieties for carotenoid accumulation did not change between the two years of production.

By choosing varieties of kale that rank highest for lutein and -carotene accumulation, vegetable producers can be assured of maximum carotenoid production for each given season.

Experimental Results  Carotenoid Variability in Kale

Choice of kale variety and production year significantly affected carotenoid levels (Table 1). The highest lutein and -carotene accumulation was for the variety ‘Toscano’. Although year 2 displayed higher carotenoid values than year 1, rank order (according to Spearman’s rank correlation) did not change between the years.

Carotenoid Variability in Spinach Choice of spinach variety also significantly affected carotenoid accumulation (Table 2). The variety ‘Spinner’ accumulated the highest amount of lutein and -carotene during the first season of production. The second season of spinach evaluation occurred in 2003 and data is currently being analyzed.

Calvolo Palmizio Nero

Couve Espanhola

Panca de Chaves

Redbor F1

SC Green Glaze

Shetland

Toscano

Winterbor F1

Carotenoid Determination Carotenoids were quantified from leaf tissue using high performance liquid chromatography analysis (HPLC) according to the method of Beecher and Howard (USDA Food Composition Laboratory, Beltsville, MD) (8).

Materials and Methods

Representative kale varieties (note differences in leaf shapes and colors).

Representative spinach varieties.

Indian Summer

Melody

Springer

11.5212.63 7.71 7.96 7.14 5.53 7.32 6.67 5.98 6.95 6.52 6.41 6.96 4.94 5.64 6.28 7.69 5.31 6.07 4.91

6.81 1.47

ToscanoCalvolo Palmizio Nero Winterbor F1PremierCouve NabicaGiant Jersey KaleSiberian Improved Crimson GardenRound Leaf KaleTall MarrowstemRedbor F1NZ Thousand HeadBonaShetlandCouve EspanholaCondorRed RussianCouve PortugueasaSC Green GlazePanca de Chaves

Mean of all varietiesLSD0.05

y

LSD0.05x

13.4313.33 9.60 9.07 8.97 8.89 8.88 8.71 8.29 8.20 8.07 7.24 7.14 7.12 6.98 6.92 6.91 6.42 6.27 6.09

8.10 1.92

10.00 7.80 5.33 7.44 5.13 4.99 5.60 4.75 4.59 5.20 5.46 4.73 4.77 3.49 4.39 4.26 5.82 4.28 4.73 3.49

5.19 1.63

9.928.077.017.687.337.357.245.546.346.606.515.815.676.395.405.975.785.664.744.32

6.331.42

Table 1. Mean valuesz (mg/100 gfw-1) of lutein and -carotene for 20 leafy kale (Brassica oleracea L.) varieties over two growing season (YR1 & YR2).

1.21 1.08

Kale Variety YR1 YR2 YR1 YR2

Lutein -carotene

z Composition of leaf samples from 3 replications, 10 plants each.LSD for differences between variety means: y within years and x between years.

12.31 12.1511.3311.1810.6210.6110.15 9.90 9.76 9.49 8.99 8.96 8.55

10.30 2.50

Longstanding Bloomsdale SpinnerIndian SummerViennaTyeeMelodyPolydaneHectorDenaliUnipak 12SpringerOlympiaCypress

Mean of all varietiesLSD0.05

y

9.3510.24 8.01 8.08 8.24 8.10 8.33 7.74 8.10 8.17 7.06 7.42 6.88

8.13 2.16

Table 2. Mean valuesz (mg/100 gfw-1) of lutein and -carotene for 13 Spinach (Spinacea oleracea L.) varieties during 2002 growing season.

Spinach Variety Lutein -carotene

z Composition of leaf samples from 4 replications, 10 plants each.y LSD for differences between variety means.