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Factors Affecting Yield and Composition of Zein Extracted from Commercial Corn Gluten Meal¹

¹Journal Paper, J-16805 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA, 50011. Project no. 0161. Research supported by the Iowa Corn Promotion Board, Center for Crops Utilization Research and the Iowa Agriculture and Home Economics Experiment Station. ²Graduate research assistant, associate professor and professor, respectively, Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011. ³Corresponding author. E-mail: dmyers@iastate.edu ⁴Professor-in-charge, Center for Crops Utilization Research, Iowa State University, Ames, IA, 50011.

Twelve corn gluten meal samples obtained from six wet-milling plants were processed into zein. Zein was extracted using 88% aqueous isopropyl alcohol at pH 12.5, followed by chilling. Protein recovery ranged from 21.3 to 32.0%, and protein purity ranged from 82.1 to 87.6%. Protein recovery increased as the protein purity increased (r = 0.76) (P < 0.01). One of the major factors influencing extraction yield was protein composition; especially α-zein content, which ranged from 53.4 to 64% of the total protein in the corn gluten meal samples. The intensity of red color of the corn gluten meal was negatively correlated with protein recovery and zein purity (r = -0.66 and -0.72, respectively) (P < 0.02).