17E-1 |
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N. A. DEAK1, P. A. Murphy1, and L. A. Johnson2. (1) Dept. of Food Science & Human Nutrition, Iowa State Univ., 2312 Food Sciences Bldg., Ames, IA 50010, (2) Center for Crops Utilization Research, Iowa State Univ., Dept. of Food Science & Human Nutrition, 1041 Food Sciences Bldg., Ames, IA 50011 There is increased interest in using individual soybean storage proteins (glycinin and b-conglycinin) as nutraceutical and functional products. Presently, there is a lack of economically viable industrial processes to produce the individual storage proteins. The objective of this study was to optimize, for future scale–up studies and producing sufficient quantities for human feeding trials, our laboratory process for fractionating glycinin and b-conglycinin from soy flour. The influence of different NaCl concentrations on the yields and purities of the protein fractions was investigated. Three different fractions are obtained in this process: a glycinin-rich, a b-conglycinin-rich, and an intermediate fraction, which is a mixture of the two proteins. Two different strategies were employed to optimize process efficiency. First, nine NaCl concentrations (0, 10, 20, 50, 100, 200, 250, 500, and 1000 mM) were evaluated during fractionation to effectively salt-in the proteins, and to obtain purer b-conglycinin-rich fractions. Second, four different dilutions (0, 0.5-, 1.0-, and 2.0-fold) at the optimum NaCl concentration were employed to improve process efficiency in salting-out the b-conglycinin. NaCl concentration significantly influenced (p < 0.05) the total protein yield of the intermediate and b-conglycinin fractions. The optimum protein yield of the b-conglycinin-rich fraction was obtained at 500 mM, but at the expense of purity. The ideal NaCl concentration was 250 mM, at which high yield and purity were achieved. At higher NaCl concentrations, the protein yields of the intermediate fractions were significantly lower, and the protein loss in the whey fraction increased gradually. At 0 and 0.5-fold dilution, the purities and yields of the b-conglycinin-rich fractions were significantly lower than at 1.0- and 2.0-fold of dilution. The process efficiency of fractionating soy protein into glycinin and b-conglycinin can be improved using 250mM concentration of NaCl, and a lower dilution factor.
Session 17E, Food Chemistry: Proteins
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