Carotenoids in durum wheat grain.

摘要

Carotenoid pigments provide the traditional yellow color of pasta and are important in moderating oxidative stresses in plants and animals. Research was conducted to determine (1) deposition and composition of carotenoid pigments in durum wheat during grain fill; (2) the distribution of carotenoid pigments in durum wheat kernels; and (3) the stability of carotenoid pigments during milling, spaghetti processing, and cooking.;Carotenoid deposition pattern was similar for all five durum cultivars, but it was different for two environments (Prosper, ND, 2005 and 2006) during grain fill. Total carotenoid pigment content increased from anthesis to physiological maturity, after which carotenoid pigment content declined in 2005 or remained constant in 2006. Reverse phase high pressure liquid chromatography (RP-HPLC) revealed that lutein was the major carotenoid (94% of total carotenoids) present in durum wheat followed by zeaxanthin, beta-cryptoxanthin, and alpha-carotene. At the time of harvest, lutein content was 809 ng/kernel in 2005 and 1170 ng/kernel in 2006.;Mature harvested grain from five durum cultivars grown at Langdon and Prosper, ND, in 2005 was pearled to obtain bran/germ (10% w/w of kernel), outer endosperm (15% w/w), and inner endosperm (33% w/w) fractions. Yellow pigments were most concentrated (9.8 mug/g) in the outer layer (bran/germ) and least concentrated (6.2 mug/g) in the inner endosperm. Lutein concentration was lowest (14.3 mug/g) in the bran/germ fraction but was more evenly distributed in the endosperm (18.7 mug/g). Zeaxanthin concentration declined inward from the bran/germ (1.3 mug/g) towards the inner endosperm (0.72 mug/g). Lutein concentration was about 18 times greater than zeaxanthin amounts in the whole kernel.;Average total yellow pigment content in the durum kernel varied from 6.5-10 mug/g, depending on cultivar and environment (Prosper and Langdon, ND, 2005 and 2006). Reduction in total yellow pigment content in milling, extrusion/drying, and cooking ranged 8-20%, 14-20%, and 22-28%, respectively. Total pigment loss during spaghetti processing was greatest for Belzer and Divide (≈20%), intermediate for Pierce (15.6%) and Maier (16.2%), and least for Dilse (14.2%) durum wheat. Lutein loss during spaghetti processing was 30-40%, and zeaxanthin loss in milling was 30-100%. Zeaxanthin was not detected in cooked spaghetti.