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Variation in Polyphenol Oxidase Activity and Quality Characteristics Among Hard White Wheat and Hard Red Winter Wheat Samples¹

¹Published as Paper 11511, Journal Series, Agricultural Research Division, University of Nebraska, Lincoln, NE 68583-0704. ²Department of Food Science and Technology, 143 Filley Hall, University of Nebraska, Lincoln, NE 68583-0919. ³Department of Agronomy, University of Nebraska, Lincoln, NE 68583-0915. ⁴Corresponding author. E-mail: agro213@unlvm.unl.edu ⁵USDA-ARS, Department of Agronomy, University of Nebraska, Lincoln, NE 68583-0915. ⁶Kansas State University, Agricultural Research Center-Hays, Hays, KS 67601. ⁷Department of Biometry, University of Nebraska, Lincoln, NE 68583-0712.

Polyphenol oxidase (PPO) has been related to an undesirable brown discoloration of wheat-based end products. Consumer acceptance and product quality are generally decreased by the darkening phenomena. Two sets of wheat samples (Triticum aestivum L.) were investigated for variation in grain and flour PPO levels. Samples included 40 advanced experimental hard white winter wheat lines grown at two Kansas locations and 10 hard red winter wheat genotypes grown at three Nebraska locations. The variability in grain and flour PPO activities was influenced by growing location and population for the hard white wheat samples. There also was a significant influence of population by growing location interactions on PPO activity in both grain and flour. Genotype and growing location both contributed to variability in flour PPO activity among the hard red wheat samples. The variation in flour PPO activities among growing locations appeared larger than variation produced by genotypes tested for the hard red wheat samples. Quality parameters, such as wheat physical properties, flour protein and ash contents, grain color, and milling yield significantly correlated with grain and flour PPO activities. Among red wheat samples, flour PPO activity was related to 100 kernel weight, first reduction flour yield, and flour ash content. Grain PPO activity was related to variation in grain color observed among hard white samples. The relationship of quality characteristics with grain and flour PPO activities varied among white and red wheat samples.