Effects of protein solubilisation and precipitation pH values on the functional properties of defatted wheat germ protein isolates
Effects of protein solubilisation and precipitation pH values on the functional properties of defatted wheat germ protein isolates
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DOI：
10.1111/ijfs.12117
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发表时间：
2013-07
影响因子：
3.3
通讯作者：
Fengru Liu;Zhengxing Chen;Li Wang;Ren Wang
中科院分区：
文献类型：
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作者：
Fengru Liu;Zhengxing Chen;Li Wang;Ren Wang
使用碱溶解和酸沉淀从脱脂小麦胚芽粉制备小麦胚芽蛋白分离物。选择具有两个独立变量（溶解pH和沉淀pH）和双变量相关性的中心复合设计用于蛋白质分离条件和功能性质的相关性分析。结果表明，菌株的蛋白质产量（Y）和功能特性（如吸水率（WA）和脂肪吸收率（FA））对溶解pH和沉淀pH均敏感，而乳化作用仅对溶解pH敏感。菌株的乳化活性（EA）和FA与产量呈高度正相关。蛋白质组分的凝胶电泳分析证明了在不同条件下分离的蛋白质之间的组成变化，高碱性条件导致蛋白质链的降解和有毒化合物的形成。表面疏水性表明，蛋白质在高碱性条件下溶解时倾向于更变性。这些构象和组成的变化，由于不同的蛋白质分离条件的蛋白质分离物的功能特性的变化。
Summary Wheat germ protein isolates were prepared from defatted wheat germ flour using alkaline solubilisation and acid precipitation. A central composite design with two independent variables (solubilisation pH and precipitation pH) and bivariate correlations was selected for the correlation analysis of the protein separation conditions and the functional properties. The results showed that the protein yield (Y) and functional properties of isolates, such as water absorption (WA) and fat absorption (FA), were sensitive to both solubilisation pH and precipitation pH, whereas the emulsification was sensitive to only solubilisation pH. Emulsifying activity (EA) and FA of isolates showed a high positive correlation with yield. Gel electrophoresis analysis of protein fractions gave evidence to the compositional changes between proteins isolated under different conditions, highly alkaline conditions result in the degradation of protein chains and formation of toxic compounds. Surface hydrophobicity suggested that proteins tend to be more denatured when solubilised at highly alkaline conditions. These conformational and compositional changes due to different protein separation conditions have contributed to the changes in functional properties of protein isolates.