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Isolation of Proteins from Plant Material
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Cooperative investigations of Crops Research Division, Agricultural Research Service, U. S. Department of Agriculture, and Department of Flour and Feed Milling Industries, Kansas Agr. Expt. Sta., Manhattan. Contribution No. 513.
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Mention in this publication of a trade product, equipment, or commercial company does not imply its endorsement by the U. S. Department of Agriculture over similar products or companies not named.
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The author expresses his appreciation to K. F. Finney for baking tests; to C. W. Deyoe for amino acid analyses; and to Rita P. Fan for assistance with analytical determinations. Archer-Daniels Midland Co., Central Soya Co., General Mills, and A. E. Staley Mfg. Co. are thanked for providing samples of soy flour.
SUMMARY
Proteins were extracted with a yield of up to 90% from wheat flour and finely powdered untoasted soya flour, with a 3M urea solution at 4°C. The urea-extracted protein contained, on hydrolysis, higher amounts of ammonia than a commercial soya protein isolate. Amino acid analysis by ion-exchange chromatography of soya proteins isolated with 3M urea showed that, on an ammonia-free basis, the urea-extracted proteins were comparable to a commercial soya protein isolate. Both had an amino acid composition comparable to that of a commercial solvent-extracted 50y0-protein soya meal. The urea-extracted proteins from wheat flour and soya flour retained their functional properties in bread-making. Extraction with 3M urea was lowered in coarsely ground soya meals and was reduced substantially by heat-treatment of soya products. Dispersibility in 3M urea at 4°C was found to be a useful parameter to evaluate the extent of heat damage to plant proteins.
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2621.1965.tb01848.x/abstract
