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03 Issues & Trends
Cereal Foods World, Vol. 63, No. 5
DOI: https://doi.org/10.1094/CFW-63-5-0217
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Purple and Blue Wheat—Health-Promoting Grains with Increased Antioxidant Activity
Heinrich Grausgruber,1,2 Klaus Atzgersdorfer,1,3 and Stefan Böhmdorfer4

1 Department of Crop Sciences, University of Natural Resources and Life Sciences, Vienna, Konrad Lorenz Str 24, 3430 Tulln an der Donau, Austria.
2 Corresponding author. Tel: +43 1 47654 957 11; E-mail: heinrich.grausgruber@boku.ac.at
3 Present address: Saatbau Linz, Maiszuchtstation Schönering, Angerweg 19, 4073 Wilhering, Austria.
4 Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Konrad Lorenz Str 24, 3430 Tulln an der Donau, Austria.


Abstract

Anthocyanins are flavonoid pigments that are responsible for red, purple, and blue colors in diverse organs in a wide array of plants. Anthocyanins also act as antioxidants, for example by scavenging free radicals. In wheat, anthocyanins can be present in the pericarp (purple anthocyanins) or aleurone (blue anthocyanins) layer of the grain. Purple and blue wheat grains, therefore, can be processed into innovative whole wheat (wholemeal) products that are rich in both dietary fiber and antioxidants. Combining the genetic components that produce purple pericarp and blue aleurone traits significantly increases the total concentration of anthocyanins and, as a result, the total antioxidant activity.





Anthocyanins are the most abundant and widely occurring flavonoid pigments and are responsible for most of the blue to blue-black and red to purple colors found in a wide variety of fruits, vegetables, flowers, leaves, roots, and other plant storage organs (9). The first anthocyanin was identified from the blue cornflower (Centaurea cyanus L.) in the early 20th century (39). Today, several hundred different anthocyanins have been identified and defined structurally. Interest in anthocyanins has increased recently because they represent natural alternatives to artificial food colorants, and research suggests they have potential health benefits due to their antioxidant properties (11,16,21,34). In wheat (Triticum spp.), pigmentation by anthocyanins can appear in almost all plant parts (Fig. 1).


Purple Pericarp and Blue Aleurone Traits

Purple wheat grains were first introduced to the scientific community by Wittmack in the late 1800s (40). The grains were originally collected in Abyssinia (northern Ethiopia) in 1872 and 1873 (40,41). In his compendium on cereal varieties, Körnicke (19) described two tetraploid, purple-grained Ethiopian wheat varieties, T. aethiopicum var. arraseita and T. aethiopicum var. schimperi. In 1905, a German expedition to Abyssinia collected seeds from purple-colored wheat, which were further distributed to researchers in Europe by Wittmack (42). At the same time, two samples of purple wheat from Abyssinia designated as “frumento eloboni” were displayed at an agricultural exhibition in Italy (42). It is clear from these publications that purple wheat from Abyssinia was brought to Europe at the end of the 19th century and was widely distributed across Europe by the beginning of the 20th century, either through further distribution by botanists or repeated introduction from East Africa (47).

At the same time, plant scientists also carried out interspecific crosses between wheat and wheat relatives and wheat and rye to transfer genes for disease resistance, winter hardiness, perennial habit, forage traits, and yield components into wheat. Breeding activities in Central Europe gave rise to various European ‘Blaukorn’ germplasm (17,33,37,46). The source of the blue aleurone trait in this material originates from einkorn wheat (46). Simultaneously, hybridization with Agropyron spp. (wheatgrass) in North America resulted in various blue-aleurone genetic wheat stocks (30,31,38,47,48).

From Genetic Studies to Breeding

Purple and blue wheat strains were widely used during the first half of the 20th century to elucidate the inheritance of grain pigmentation (7,17,47). Finally, the purple grain color was transferred into advanced bread wheat material (8). In the 1960s and 1970s, purple wheat germplasm was developed worldwide for purposes such as the demarcation of feed wheat quality (15), development of hybrid wheat systems (5), and determination of outcrossing rates in the self-pollinating wheat crop (10). In the early 1980s, the first commercial purple wheat variety was released in New Zealand, and novel, eye-catching kibbled and whole grain products appeared on the market (44). Since then, commercial purple wheat varieties have also been released in Australia, Canada, China, and many European countries. In contrast, to the best of our best knowledge, no commercial varieties of blue wheat have been released to date except in Austria (29) and China (14).

Black-grained wheat germplasm has been reported by Chinese researchers (26,35,45). The dark or “black” grain color found in wheat is not due to melanin-like pigments, as is the case in barley (43), but results from a combination of purple pericarp and blue aleurone traits (6,35,36). The abundance of wheat with dark colored grains in China is most likely due to the frequent implementation of wide crosses with wild relatives in Chinese wheat breeding programs.

Anthocyanin Profile, Antioxidant Activity, and Health

Separation of grain anthocyanins by different chromatographic methods revealed distinct anthocyanin profiles for blue and purple wheats. In blue wheat, delphinidin was identified as the predominant anthocyanin aglycon, whereas cyanidin is the main aglycon in purple wheat. Generally, the anthocyanin profile is more complex in purple wheat (2,4,6,13,18,20,28,36). The results with regard to profile and total anthocyanin content are somewhat contradictory and point to interactions between genotypes and environments.

Various studies have demonstrated higher antioxidant properties for purple and blue wheat varieties compared with red or white varieties. The composition of anthocyanins, such as type of aglycon and sugar moiety, seems to have a significant impact on antioxidant properties (1,16). The highest radical-scavenging activity was reported for a black grain genotype (25) and can be confirmed in our breeding material (Fig. 2). Although other compounds, such as phenolic acids, influence antioxidant capacity, anthocyanins play a major role in the overall free radical-scavenging capacity of colored wheat varieties (14). Therefore, breeding for high anthocyanin content by combining the genetic components of purple pericarp and blue aleurone traits is a promising approach to achieve wheat germplasm with high antioxidant content.


Products and Effects of Processing

A wide range of innovative products incorporating anthocyanin-pigmented wheat varieties has been experimentally and commercially developed (22). In addition to New Zealand, where specialty bread types made from purple wheat were first marketed (27,44), purple wheat products, especially whole grain breads (Fig. 3) and breakfast cereals, have found a niche market in Central Europe and Canada, where they are marketed under trademarked brands (e.g., PurPur® [backaldrin International The Kornspitz Company GmbH] or AnthoGrain™ [InfraReady Products Ltd.]). In China, many food manufacturing enterprises have developed products made with black wheat, such as soy sauce, cakes, and (instant) noodles (22).

Foods made with anthocyanin-rich wheat grains may offer health benefits due to the antioxidant activity of the pigments (12,22); however, processing does have a significant impact on anthocyanins and their antioxidant properties. Fractionation can significantly increase the concentration of anthocyanins (1,32), whereas heat and light can degrade anthocyanins during drying, processing, and storage (23,24). In addition to the use of purple and blue wheat grains for food, extraction of anthocyanins from the bran (3) may also enable their use in nonfood industries. With respect to health benefits, further research on the bioavailability and degradation of anthocyanins after and during processing is needed. However, purple and blue wheat grains definitely increase the diversity of potential cereal products, and by consuming whole grain purple wheat products, consumers can also benefit from a fiber-rich diet.

Conflicts of Interest

The authors declare no conflict of interest with respect to the mentioned companies.

 

References

  1. Abdel-Aal, E.-S. M., Abou-Arab, A. A., Gamel, T. H., Hucl, P., Young, J. C., and Rabalski, I. Fractionation of blue wheat anthocyanin compounds and their contribution to antioxidant properties. J. Agric. Food Chem. 56:11171, 2008.
  2. Abdel-Aal, E.-S. M., and Hucl, P. Composition and stability of anthocyanins in blue-grained wheat. J. Agric. Food Chem. 51:2174, 2003.
  3. Abdel-Aal, E.-S. M., Hucl, P., and Rabalski, I. Compositional and antioxidant properties of anthocyanin-rich products prepared from purple wheat. Food Chem. 254:13, 2018.
  4. Abdel-Aal, E.-S. M., Young, J. C., and Rabalski, I. Anthocyanin composition in black, blue, pink, purple, and red cereal grains. J. Agric. Food Chem. 54:4696, 2006.
  5. Barabás, Z. Method of producing hybrid wheat by means of marker genes. Cereal Res. Commun. 1:45, 1973.
  6. Böhmdorfer, S., Oberlerchner, J. T., Fuchs, C., Rosenau, T., and Grausgruber, H. Profiling and quantification of grain anthocyanins in purple pericarp × blue aleurone wheat crosses by high-performance thin-layer chromatography and densitometry. Plant Meth. 14:29, 2018.
  7. Caporn, A. S. C. On a case of permanent variation in the glume length of extracted parental types and the inheritance of purple colour in the cross Triticum polonicum × T. eloboni. J. Genet. 7:259, 1918.
  8. Copp, L. G. L. Purple grain in hexaploid wheat. Wheat Inf. Serv. 19-20:18, 1965.
  9. Davies, K. M., Schwinn, K. E., and Gould K. S. Anthocyanins. Page 355 in: Encyclopedia of Applied Plant Sciences, 2nd ed. Vol. 2, Breeding Genetics and Biotechnology. B. Thomas, B. G. Murray, and D. J. Murphy, eds. Academic Press, Waltham, MA, 2017.
  10. Griffin, W. B. Outcrossing in New Zealand wheats measured by occurrence of purple grain. N.Z. J. Agric. Res. 30:287, 1987.
  11. He, J., and Giusti, M. M. Anthocyanins: Natural colourants with health-promoting properties. Annu. Rev. Food Sci. Technol. 1:163, 2010.
  12. Hirawan, R., Diehl-Jones, W., and Beta, T. Comparative evaluation of the antioxidant potential of infant cereals produced from purple wheat and red rice grains and LC-MS analysis of their anthocyanins. J. Agric. Food Chem. 59:12330, 2011.
  13. Hosseinian, F. S., Li, W., and Beta, T. Measurement of anthocyanins and other phytochemicals in purple wheat. Food Chem. 109:916, 2008.
  14. Hu, C., Cai, Y. Z., Li, W., Corke, H., and Kitts, D. D. Anthocyanin characterization and bioactivity assessment of a dark blue grained wheat (Triticum aestivum L. cv. Hedong Wumai) extract. Food Chem. 104:955, 2007.
  15. Jensen, N. F., Tyler, L. J., and Driscoll, C. J. Markers for wheats of feed quality. Wheat Newsl. 8:57, 1962.
  16. Kähkonen, M. P., and Heinonen, M. Antioxidant activity of anthocyanins and their aglycons. J. Agric. Food Chem. 51:628, 2003.
  17. Kattermann, G. Farbxenien bei Weizenkreuzungen und das erbliche Verhalten blaugefärbter Aleuronschicht bei der verwendeten neuartigen Weizenrasse im allgemeinen. Z. Züchtg. A Pflanzenzüchtg. 17:413, 1932.
  18. Knievel, D. C., Abdel-Aal, E.-S. M., Rabalski, I., Nakamura, T., and Hucl, P. Grain colour development and the inheritance of high anthocyanin blue aleurone and purple pericarp in spring wheat (Triticum aestivum L.). J. Cereal Sci. 50:113, 2009.
  19. Körnicke, F. Die Arten und Varietäten des Getreides. Verlag Emil Strauss, Bonn, 1885.
  20. Krüger, S., and Morlock, G. E. Fingerprinting and characterization of anthocyanins in 94 colored wheat varieties and blue aleurone and purple pericarp wheat crosses. J. Chromatogr. A 1538:75, 2018.
  21. Li, D., Wang, P., Luo, Y., Zhao, M., and Chen, F. Health benefits of anthocyanins and molecular mechanisms: Update from recent decade. Crit. Rev. Food Sci. Nutr. 57:1729, 2017.
  22. Li, W., and Beta, T. Flour and bread from black-, purple-, and blue-coloured wheats. Page 59 in: Flour and Breads and Their Fortification in Health and Disease Prevention. V. R. Preedy, R. R. Watson, and V. B. Patel, eds. Academic Press, London, 2011.
  23. Li, W., Pickard, M. D., and Beta, T. Evaluation of antioxidant activity and electronic taste and aroma properties of antho-beers from purple wheat grain. J. Agric. Food Chem. 55:8958, 2007.
  24. Li, W., Pickard, M. D., and Beta, T. Effect of thermal processing on antioxidant properties of purple wheat bran. Food Chem. 104:1080, 2007.
  25. Li, W., Shan, F., Sun, S., Corke, H., and Beta, T. Free radical scavenging properties and phenolic content of Chinese black-grained wheat. J. Agric. Food Chem. 53:8533, 2005.
  26. Li, Y., Ma, D., Sun, D., Wang, C., Zhang, J., Xie, Y., and Guo, T. Total phenolic, flavonoid content, and antioxidant activity of flour, noodles, and steamed bread made from different colored wheat grains by three milling methods. Crop J. 3:328, 2015.
  27. Lindley, T. N., and Larsen, N. G. Cereal processing in New Zealand: Inversion, diversification, innovation, management. Page 273 in: Cereals: Novel Uses and Processes. G. M. Campbell, C. Webb, and S. L. McKee, eds. Plenum Press, NY, 1997.
  28. Liu, Q., Qiu, Y., and Beta, T. Comparison of antioxidant activities of different colored wheat grains and analysis of phenolic compounds. J. Agric. Food Chem. 58:9235, 2010.
  29. Martinek, P., Škorpík, M., Chrpová, J., Fučik, P., and Schweiger, J. Development of the new winter wheat variety Skorpion with blue grain. Czech J. Genet. Plant Breed. 49:90, 2013.
  30. Morrison, L. A., Metzger, R. J., and Lukaszewski, A. J. Origin of the blue-aleurone gene in Sebesta Blue wheat genetic stocks and a protocol for its use in apomixis screening. Crop Sci. 44:2063, 2004.
  31. Qualset, C. O., Soliman, K. M., Jan, C.-C., Dvořák, J., McGuire, P. E., and Vogt, H. E. Registration of UC66049 Triticum aestivum blue aleurone genetic stock. Crop Sci. 45:432, 2005.
  32. Siebenhandl, S., Grausgruber, H., Pellegrini, N., Del Rio, D., Fogliano, V., Pernice, R., and Berghofer, E. Phytochemical profile of main antioxidants in different fractions of purple and blue wheat, and black barley. J. Agric. Food Chem. 55:8541, 2007.
  33. Škorpík, M., Rod, J., Šíp, V., Sehnalová, J., and Košner, J. Coloured wheat from the effects of E. Tschermak. Acta Agron. Acad. Sci. Hung. 32:147, 1983.
  34. Smeriglio, A., Barreca, D., Bellocco, E., and Trombetta, D. Chemistry, pharmacology and health benefits of anthocyanins. Phytother. Res. 30:1265, 2016.
  35. Sun, S., Sun, Y., Yuan, W., Yan, W., Pei, Z., Zhang, M., and Bai, Y. Breeding and qualitative analysis for black grain wheat 76 of superior quality. (In Chinese, with English abstract) Acta Agron. Sin. 25:50, 1999.
  36. Syed Jaafar, S. N., Baron, J., Siebenhandl-Ehn, S., Rosenau, T., Böhmdorfer, S., and Grausgruber, H. Increased anthocyanin content in purple pericarp × blue aleurone wheat crosses. Plant Breed. 132:546, 2013.
  37. Tschermak-Seysenegg, E. Wirkliche, abgeleitete und fragliche Weizenroggenbastarde (Triticale-Formen). Cytologia Fujii Jubilaei 2:1003, 1937.
  38. Tschermak-Seysenegg, E. Beiträge zur züchterischen und zytologischen Beurteilung der Weizen-Roggen- und Weizen-Quecken-Bastarde. Z. Züchtg. A Pflanzenzüchtg. 22:397, 1938.
  39. Willstätter, R., and Everest, A. E. Untersuchungen über die Anthocyane: I. Über den Farbstoff der Kornblume. Justus Liebigs Ann. Chem. 401:189, 1913.
  40. Wittmack, L. Purpurviolette Weizenkörner. Monat. Vereins Beförderung Gartenbaues Preußischen Staaten 1879:479, 1879.
  41. Wittmack, L. Violette Weizenkörner. Sitzungsber. Gesellschaft Naturforschender Freunde, Berlin 1906:103, 1906.
  42. Wittmack, L. Abessinische Samen und deren Anbau-Ergebnisse. Sitzungsber. Gesellschaft Naturforschender Freunde, Berlin 1907:31, 1907.
  43. Woodward, R. W. Inheritance of a melaninlike pigment in the glumes and caryopses of barley. J. Agric. Res. 63:21, 1941.
  44. Wright, D. Novelty cereal grains. Page 135 in: Floreat Scientia: Celebrating New Zealand’s Agrifood Innovation. P. J. Moughan and P. McCool, eds. Wairau Press, Auckland, NZ, 2011.
  45. Yao, J., Yao, G., Yang, X., and Qian, C. Preliminary studies on inheritance of seed coat color in Qinghai black wheat. (In Chinese, with English abstract) J. Triticeae Crops 27:791, 2007.
  46. Zeller, F. J., Cermeno, M. C., and Miller, T. E. Cytological analysis on the distribution and origin of the alien chromosome pair conferring blue aleurone colour in several European common wheat (Triticum aestivum L.) strains. Theor. Appl. Genet. 81:551, 1991.
  47. Zeven, A. C. Wheats with purple and blue grains: A review. Euphytica 56:243, 1991.
  48. Zheng, Q., Bin, L., Hongwei, L., and Zhensheng, L. Utilization of blue-grained character in wheat breeding derived from Thinopyrum ponticum. J. Genet. Genomics 36:575, 2009.