Distribution of carotenoids in endosperm, germ, and aleurone fractions of cereal grain kernels Victoria U. Ndolo a , Trust Beta a,b,⇑ a University of Manitoba, Department of Food Science, Winnipeg, Manitoba, Canada R3T 2N2 b University of Manitoba, Richardson Centre for Functional Foods & Nutraceuticals, Winnipeg, MB, Canada R3T 2N2 article info Article history: Received 19 July 2012 Received in revised form 21 December 2012 Accepted 10 January 2013 Available online 23 January 2013 Keywords: Non-corn cereals Yellow corn Aleurone Carotenoids Lutein Zeaxanthin abstract To compare the distribution of carotenoids across the grain, non-corn and corn cereals were hand dis- sected into endosperm, germ and aleurone fractions. Total carotenoid content (TCC) and carotenoid com- position were analysed using spectrophotometry and HPLC. Cereal carotenoid composition was similar; however, concentrations varied significantly (p < 0.05). Endosperm fractions had TCC ranging from 0.88 to 2.27 and 14.17 to 31.35 mg/kg in non-corn cereals and corn, respectively. TCC, lutein and zeaxanthin in germ fractions were higher in non-corn cereals than in corn. Lutein and zeaxanthin contents were lower in non-corn cereal endosperms. The aleurone layer had zeaxanthin levels 2- to 5-fold higher than lutein among the cereals. Positive significant correlations (p < 0.05) were found between TCC, carotenoids analysed by HPLC and DPPH results. This study is the first to report on carotenoid composition of the aleurone layer. Our findings suggest that the aleurone of wheat, oat, corn and germ of barley have signif- icantly enhanced carotenoid levels. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Increased interest in functional foods requires more informa- tion on the phytochemicals including carotenoids in grain cereals that have health enhancing properties. Carotenoids are among the abundant families of pigments in nature that are responsible for the yellow, orange and red colours of fruits, vegetables and grains. They form part of the antioxidant system in seeds (Howitt & Pogson, 2006). Xanthophyll carotenoids, which include lutein and zeaxanthin are recognised for their antioxidant properties (Gentili & Caretti, 2011; Leenhardt et al., 2006; Miller, Sampson, Candeias, Bramley, & RiceEvans, 1996). Carotenoids act as radical scavengers and singlet oxygen quenchers (Leenhardt et al., 2006). Epidemiological studies have shown that carotenoid-rich foods re- duce the risk of degenerative diseases, such as cancer, cardiovascu- lar diseases, and age-related macular degeneration and also maintain skin health (Burkhardt & Boehm, 2007; Rice-Evans, Sampson, Bramley, & Holloway, 1997; Roberts, Green, & Lewis, 2009). Although a minor component in cereals (Irakli, Samanidou, & Papadoyannis, 2011), some grains contain higher and others lower content of carotenoids compared to fruits and vegetables (Abdel- Aal et al., 2002; Humphries & Khachik, 2003). However, carotenoid content is an important characteristic in the utilisation of cereals such as durum wheat for pasta production (Hentschel et al., 2002). Several authors studied carotenoid content and composition in whole grain wheat (Abdel-Aal, Young, Rabalski, Hucl, & Fregeau- Reid, 2007; Adom, Sorrells, & Liu, 2003; Hentschel et al., 2002; Pan- fili, Fratianni, & Irano, 2004) maize or yellow corn (Kimura, Kobori, Rodriguez-Amaya, & Nestel, 2007; Luterotti & Kljak, 2010, and bar- ley (Goupy, Hugues, Boivin, & Amiot, 1999). The main carotenoids in cereal grains are lutein and zeaxanthin (Hentschel et al., 2002; Panfili et al., 2004). Lutein was the most abundant carotenoid in 11 wheat varieties studied by Adom et al. (2003). Okarter, Liu, Sorr- ells, and Liu (2010) found higher levels of lutein and zeaxanthin in eight diverse whole wheat varieties than reported by Adom and others. Zeaxanthin was the dominant carotenoid in maize whereas lutein was the main component in oat, barley, spelt and durum wheat (Panfili et al., 2004). Studies on carotenoid content and com- position mainly used durum wheat, bread wheat, specialty wheat (Einkorn, Khorasan) (Abdel-Aal et al., 2002, 2007; Hidalgo, Brandolini, Pompei, & Piscozzi, 2006) yellow corn (Hulshof, Kosmeijer-Schuil, West, & Hollman, 2007; Kurilich & Juvik, 1999a) while barley and oat were rarely used (Goupy et al., 1999; Panfili et al., 2004). Only a few studied distribution of carote- noids in grain kernels and their fractions (Borrelli, De Leonardis, Platani, & Troccoli, 2008; Hentschel et al., 2002; Panfili et al., 2004). There is limited or no information on carotenoid composi- tion of the aleurone layer. Although the study used hand dissected fractions, these frac- tions can be obtained mechanically at large scale during milling 0308-8146/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodchem.2013.01.014 ⇑ Corresponding author at: University of Manitoba, Department of Food Science, Winnipeg, Manitoba, Canada R3T 2N2. Tel.: +1 204 474 8214; fax: +1 204 474 7630. E-mail address: Trust.Beta@ad.umanitoba.ca (T. Beta). Food Chemistry 139 (2013) 663–671 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem