Variation in the concentrations of phenolic compounds and carotenoids in the grain of a large collection of Triticum durum Desf. accessions

Carotenoids and phenolic compounds play an important role in durum wheat grain by influencing its health-promoting properties and processing suitability. The aim of this study was to determine the variability in the concentrations of carotenoids and phenolic compounds in genetic resources that can be potentially used to breed new durum wheat varieties. A total of 101 spring accessions from Germplasm Resource Information Network (GRIN) and three reference cultivars were examined. The concentrations of eight flavonoids (apigenin, catechin, kaempferol, luteolin, naringenin, quercetin, rutoside, and vitexin), eleven bound phenolic acids (4-hydroxybenzoic, caffeic, chlorogenic, ferulic, gallic, p-coumaric, protocatechuic, sinapic, syringic, t-cinnamic, vanillic acids, and vanillin), and three carotenoids (lutein, zeaxanthin, and β-carotene) were determined. Quercetin and naringenin were the predominant flavonoids (45.7 and 33.7 mg kg−1, respectively), whereas ferulic acid and t-cinnamic acid were the predominant phenolic acids (660.1 and 498.2 mg kg−1, respectively). The grain of ten accessions (9.8%) contained more than 3 mg kg−1 of lutein, and lutein concentration exceeded 6 mg kg−1 in the grain of five accessions (4.9%). The antioxidant activity of grain (ABTS) was positively correlated with the total content of all analyzed metabolites (r = 0.5435), but no linear correlations were observed between ABTS and each of the three examined groups of compounds.