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Genotypic and Environmental Effects on Color and Discoloration Potential of Barley in Food Products

¹Graduate research assistant, Department of Food Science & Human Nutrition, Washington State University, Pullman, WA 99164-6376. ²Professor and assistant professor, respectively, Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420. ³Corresponding author. Phone: 509-335-8230. E-mail: bbaik@wsu.edu

Twelve genotypes of barley, including hulled and hulless proanthocyanidin-containing and hulled proanthocyanidin-free types, were grown in five environments (location-year combination) to determine the relative contribution of genotype and environment on quality traits associated with discoloration potential of barley. Barley grains were abraded and milled into flour. Protein, ash, total polyphenol content, and polyphenol oxidase (PPO) activity were determined. Brightness (L*) of abraded kernels, cooked kernels, gels, and dough sheets were determined and used as indicators of discoloration potential. Genetic factors were more important in determining total polyphenol content, PPO activity, and brightness of dough sheets and as important as environmental factors for protein and ash content. Across environments, L* of dough sheets was consistently higher in proanthocyanidin-free barley (73–76) than in proanthocyanidin-containing barley (59–70). Total polyphenol content of abraded grains was highest in barley grown in a dry area at 0.18%, lower in high rainfall areas at 0.13%, and lowest in irrigated areas at 0.12%. Genotype (G) by environment (E) interactions were significant for all traits, except for brightness of cooked kernels. However, the effects of the G × E interactions were generally small compared with either the genetic or the environmental effect alone and primarily due to changes in magnitude rather than in rank. Stability analyses confirmed the nature of the G × E interactions.