Carotenoids are orange and yellow pigments found in plants which play an important role in human health. Winter squash cultigens often have a high carotenoid content; however, carotenoid contents and profiles among currently popular North American cultivars have not been adequately characterized, nor has carotenoid diversity within cultigens of C. maxima and C. moschata been adequately explored. In the present study, several cultigens of C. moschata and C. maxima, including popular cultivars Waltham Butternut, Sunshine, and Thunder, were grown at research farms in Durham, NH in 2007, 2008, and 2009, and harvested at either 40 or 60 days after pollination (DAP), and stored for 0, 30 or 60 days at 15 oC prior to preparing samples. Total carotenoid contents were determined spectrophotometrically and carotenoid profiles were determined using high performance liquid chromatography (HPLC). Carotenoid contents in fruit samples of C. maxima cultigens harvested at 60 DAP ranged from 146 to 320 μg·g-1 FW, compared to contents of 274 to 623 μg·g-1 FW after storage for 60 d. Carotenoid contents were lower among Cucurbita moschata cultigens, ranging from 42 to145 μg·g-1 FW at 60 d harvest, and from 84 to 239 μg·g-1 FW after storage for 60 d. The predominant carotenoids identified in C. maxima kabocha hybrids were the nutritionally important carotenoids, β-carotene, zeaxanthin and lutein, and non-nutritionally important carotenoids neoxanthin and lutein-5,6-epoxide. The nutritionally beneficial carotenoids α-carotene, β-carotene and lutein were identified in cultigens of C. moschata, along with neoxanthin and violaxanthin, carotenoids with no known role in human nutrition. There was relatively little variability in carotenoid profiles among the kabocha hybrids, and the average values for lutein and β-carotene were 46 μg·g-1 FW and 41 μg·g-1 FW, respectively. There was considerable variability in carotenoid profiles among the C. moschata cultigens. Beta-carotene varied from as low as 17.3 μg·g-1 FW in ‘Waltham Butternut’ to as high as 114.2 μg·g-1 FW in the inbred line NH.Mo421. Lutein varied from 22.3 μg·g-1 FW in NH.Mo421 to 59.9 μg·g-1 FW in NH.Mo851. Both species exhibited variability in the proportion of nutritionally beneficial to total carotenoids and in the proportion of xanthophylls (hydroxyl carotenoids) that were esterified to fatty acid esters.

Carotenoid content and composition in winter squash, (Cucurbita maxima Duch.) and (Cucurbita moschata Duch.): Variability associated with different cultigens, harvest dates, and storage times

249th National Meeting (2015)

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