Charge Compensation, Phase Diagram, and Protein Aggregation in Soy Protein鈥揋um Arabic Complex Formation

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• 作者：Die Dong ; Yufei Hua ; Yeming Chen ; Xiangzhen Kong ; Caimeng Zhang ; Qi Wang
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2013
• 出版时间：April 24, 2013
• 年：2013
• 卷：61
• 期：16
• 页码：3934-3940
• 全文大小：384K
• 年卷期：v.61,no.16(April 24, 2013)
• ISSN：1520-5118

文摘

Mixtures of soy protein (SP) and gum arabic (GA) formed an electrostatic complex in a relatively narrow pH range at very low ionic strength. The conditions under which the complexes could be formed were determined using turbidimetric measurements first. In salt-free condition and 1:1 SP/GA mixture, critical pH values with the formation of soluble (pH_c = 4.40), insoluble (pH_蠁1 = 3.55), and maximum (pH_opt = 3.15) complexes were observed. As SP/GA ratios increased from 1:4 to 8:1, critical pH values shifted toward higher pH. Charge densities (ZN) for SP and GA were calculated from electrophoretic mobility using soft particle analysis theory. Results showed that a 1:1 charge ratio at pH_蠁1 was found at any SP/GA ratio, indicating that charge compensation was fulfilled for SP/GA insoluble complex formation. A SP鈥揋A鈥搘ater ternary phase diagram was built at pH 4.0. The influence of the total biopolymer concentration (0鈥?0% w/w) and SP/GA ratio was represented in the phase diagram. At a total concentration of 0.10%, results were consistent with the turbidity measurement; that is, no phase separation occurred at an SP/GA ratio lower than 1:2 at pH 4.0. Salt effect (NaCl, 0鈥?00 mmol/L) on SP/GA complexes was discussed. Results indicated that SP/GA complexing, which led to the formation of turbidity peaks at pH 3.2, was suppressed when NaCl concentrations were 鈮?0 mmol/L, whereas the remarkable increase in turbidity around pH 5.0 was caused by the aggregation of soy protein molecules on which gum arabic could be adsorbed.

Keywords:

complex formation; soy protein; gum arabic; charge compensation; phase diagram; protein aggregation