Spectrophotometric Determination of Yellow Pigment Content and Evaluation of Carotenoids by High-Performance Liquid Chromatography in Durum Wheat Grain

Abstract

The so-called "yellow pigment" content of durum wheat has been used for a long time as an indicator of the color quality of durum wheat and pasta products. For decades the chemical nature of these pigments has been assigned to carotenoids, mainly to the xanthophyll lutein and its fatty acid esters. The chemical composition of the yellow pigments of eight German durum wheat cultivars was studied. Grains were milled on a laboratory mill. Pigment extraction of millstream fractions was performed according to the optimized ICC standard method 152 procedure, and the chemical composition of the extract was analyzed by isocratic reversed phase high-performance liquid chromatography. all-trans-Lutein ranged from 1.5 to 4 mg kg(-1), and zeaxanthin was found in traces. No lutein esters and carotenes were detected. Surprisingly, the fraction of carotenoids of the complete yellow pigment content amounted to only 30-50% of the yellow pigment quantities, so there are still compounds in durum wheat not yet identified that contribute considerably to the yellow color of the grain extracts. The isolation and chemical identification of those pigments are under investigation.

Association between allelic variation at the Phytoene synthase 1 gene and yellow pigment content in the wheat grain

“…durum) is lutein (Hentschel et al 2002), which confers a natural yellow color to pasta products. This is a desirable quality trait for pasta and, therefore, an important target in durum wheat breeding programs.…”

Molecular characterization of durum and common wheat recombinant lines carrying leaf rust resistance (Lr19) and yellow pigment (Y) genes from Lophopyrum ponticum

“…The final yellow color of the pasta is the result of the accumulation of a mixture of natural carotenoid pigments present in the seeds and of their oxidative degradation by lipoxygenase (Lox) activity (Troccoli et al 2000). It was also suggested that, in addition to the carotenoids, some other compounds contribute to the yellow pigments present in the durum wheat seeds (Hentschel et al 2002).…”

Cloning and comparative analysis of carotenoid β-hydroxylase genes provides new insights into carotenoid metabolism in tetraploid (Triticum turgidum ssp. durum) and hexaploid (Triticum aestivum) wheat grains

“…High levels of yellow pigments in pasta/tetraploid wheat are favored by durum wheat breeders due to consumer preferences. In contrast, consumers desire white flour for bread baking, and consequently hexaploid/ bread wheat (Triticum aestivum) varieties have been selected for very low levels of carotenoid (yellow) pigments (Hentschel et al, 2002). Carotenoid accumulation during wheat endosperm development was previously examined using a doubled haploid bread wheat population (Howitt et al, 2009).…”