Phytochemical Profile of Main Antioxidants in Different Fractions of Purple and Blue Wheat, and Black Barley SUSANNE SIEBENHANDL,* ,† HEINRICH GRAUSGRUBER, ‡ NICOLETTA PELLEGRINI, § DANIELE DEL RIO, § VINCENZO FOGLIANO, | RITA PERNICE, | AND EMMERICH BERGHOFER † Department of Food Science and Technology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, 1190 Vienna, Austria, Department of Applied Plant Sciences and Plant Biotechnology, University of Natural Resources and Applied Life Sciences, Gregor Mendel Strasse 33, 1180 Vienna, Austria, Department of Public Health, University of Parma, 39 Via Volturno, 43100 Parma, Italy, and Department of Food Science, University of Naples “Federico II”, Parco Gussone, 80055 Portici, Naples, Italy Two pigmented wheat genotypes (blue and purple) and two black barley genotypes were fractionated in bran and flour fractions, examined, and compared for their free radical scavenging properties against 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (Trolox equivalent antioxidant capacity, TEAC), ferric reducing antioxidant power (FRAP), total phenolic content (TPC), phenolic acid composition, carotenoid composition, and total anthocyanin content. The results showed that fractionation has a significant influence on the antioxidant properties, TPC, anthocyanin and carotenoid contents, and phenolic acid composition. Bran fractions had the greatest antioxidant activities (1.9–2.3 mmol TEAC/100 g) in all four grain genotypes and were 3–5-fold higher than the respective flour fractions (0.4–0.7 mmol TEAC/100 g). Ferulic acid was the predominant phenolic acid in wheat genotypes (bran fractions) while p-coumaric acid was the predominant phenolic acid in the bran fractions of barley genotypes. High-performance liquid chromatography analysis detected the presence of lutein and zeaxanthin in all fractions with different distribution patterns within the genotypes. The highest contents of anthocyanins were found in the middlings of black barley genotypes or in the shorts of blue and purple wheat. These data suggest the possibility to improve the antioxidant release from cereal-based food through selection of postharvest treatments. KEYWORDS: Anthocyanins; carotenoids; phenolics; colored grain; Hordeum; Triticum INTRODUCTION Since their domestication, cereal grains have become staple foods providing protein, carbohydrates, and fiber. In recent years, minor bioactive compounds, for example, polyphenols and carotenoids, have attracted more and more interest from both researchers and food manufacturers as health-promoting and disease-preventing effects were found in both in vitro and in vivo studies. It appears that phytochemicals linked to the fiber skeleton, in addition to or instead of the fiber itself, are responsible for the reduced risk of various diseases associated with oxidative stress, such as cancer and cardiovascular and neurodegenerative diseases (1). Because vitamins C and E are absorbed in the upper segments of the intestine, polyphenols constitute together with carotenoids the only dietary antioxidants present in the colon in valuable concentrations (2, 3). In cereals, the predominant phenolic acid is ferulic acid, representing up to 90% of total polyphenols (4). Almost all ferulic acid is found in the pericarp and aleurone layer (5, 6), mainly ester-linked to polymers in the plant cell wall (7, 8). Free phenolics account only for a small percentage of the total phenolic content, for example, 16–28% in whole wheat flours (9). The inverse association between whole grain consumption and incidence of certain chronic diseases could be explained by the release of phenolics in the colon (10, 11). Supporting such a hypothesis, an apparent increase of antioxidant release during enzymatic incubation was found in in vitro studies (12, 13). Other phenolic compounds present in valuable amounts in pigmented cereals are anthocyanins (14). Anthocyanins in wheat and barley are found either in the pericarp or in the aleurone * To whom correspondence should be addressed. Tel: +43(0)1 36006-6607. Fax: +43(0)1 36006-6251. E-mail: susanne.siebenhandl@ boku.ac.at. † Department of Food Science and Technology, University of Natural Resources and Applied Life Sciences. ‡ Department of Applied Plant Sciences and Plant Biotechnology, University of Natural Resources and Applied Life Sciences. § University of Parma. | University of Naples “Federico II”. J. Agric. Food Chem. 2007, 55, 8541–8547 8541 10.1021/jf072021j CCC: $37.00  2007 American Chemical Society Published on Web 09/26/2007