Selecting for high anthocyanins and high carotenoids to enhance the antioxidant activity of durum wheat

In recent years, the interest towards functional properties of foods has increased progressively and a relevant role has been played by antioxidant compounds, such as anthocyanins, carotenoids and phenolic acids, able to scavenge free radicals. Purple wheat contains higher levels of anthocyanins than conventional wheat cultivars. Durum wheat is also characterized by relevant levels of carotenoids, compared to soft wheat. The aim of this work has been to breed durum wheat lines characterized by high anthocyanin and high carotenoid levels. This strategy enhances the antioxidant activity of the derived whole meal and processed products (Pasqualone et al., 2015). Purple wheat line CItr 14629 (Triticum turgidum ssp. durum (Desf.) Husnot), derived from an Ethiopic landrace kindly provided by the United States Department of Agriculture (USDA), and the Italian durum wheat cv. Grecale, characterized by high carotenoid content, have been crossed and the segregant generations grown and evaluated according to the pedigree method. Twenty-five F6 lines has been selected on the basis of pericarp color, plant height, 1000-seed weight, protein content, and yellow index of whole meal flour (known to be related to carotenoid pigments). The total anthocyanins content of these 25 lines, all characterized by maximum score for visual inspection of pericarp color (score = 5, range 1-5 from yellow to dark purple), ranged from 0.94 to 43.06 mg/kg cyanidin-3-glucoside (Cy-3-Glu) on dry matter, whereas the purple parent showed a mean value of 37.13 mg/kg Cy-3-Glu (d.m.). The variability of this range evidenced that the visual evaluation of pericarp color, usually considered for selecting purple wheats (Knievel et al., 2009), is not sufficiently precise compared to spectrophotometric measure of total anthocyanins in the extracts obtained from whole meal. The lines showing the highest anthocyanin content will be characterized for the single anthocyanins and for the major phenolic acids by means of HPLC analysis. No correlation was found between total anthocyanin content and the a* colorimetric index of whole meal. Protein content of the selected lines was comprised between 13.3% and 17.9% d.m., whereas 1000-seed weight ranged from 33.3 g to 56.3 g. Yellow index was in the range 12.9-14.6. Plant height of the selected lines was lowered to 80-90 cm in comparison to 130 cm of the Ethiopian parental line. The selected lines are currently under agronomic evaluation in different field trials and different nutritional traits will be particularly considered to assess the grain and flour quality.