氯化钙对甘薯蛋白乳化特性的影响

【目的】研究不同氯化钙浓度（0.05、0.10、0.15、0.20、0.25 mol?L-1,pH 7.0）对甘薯蛋白乳化特性的影响。【方法】分别对甘薯蛋白乳化液的乳化颗粒平均粒径（d4,3）、乳化活性指数、乳析指数、界面性质（界面吸附蛋白浓度及组成）和流变性质进行测定。【结果】添加0.05 mol?L-1氯化钙后甘薯蛋白乳化活性指数由未添加氯化钙的30.3 m2?g-1显著降低为27.6 m2?g-1,d4,3从4.2 μm增大至4.42 μm（P＜0.05）。然而,随着氯化钙浓度进一步升高（0.10—0.25 mol?L-1）,d4,3显著增大（P＜0.05）而甘薯蛋白乳化活性指数变化不显著（P＞0.05）。此外,添加较高浓度的氯化钙能显著地增加乳化液的乳析指数和初始表观黏度,且界面吸附蛋白的浓度也显著提高（P＜0.05）。SDS-PAGE分析发现,Sporamin A不易被甘薯蛋白乳化界面吸附,且乳化界面和乳化液中均存在＞66 kD的S-S键高分子聚合物。【结论】 钙离子与甘薯蛋白结合能改变其结构,进而影响甘薯蛋白的乳化特性。

Effect of Calcium Chloride on Emulsifying Properties of Sweetpotato Soluble Protein

【Objective】 The effect of different concentrations of calcium chloride (0.05, 0.10, 0.15, 0.20, 0.25 mol?L-1, pH 7.0) on emulsifying properties of sweetpotato protein (SPP) was investigated. 【Method】 Droplet average size (d4,3), emulsifying activity index (EAI), creaming index (CI), interfacial properties and rheological properties were respectively determined. 【Result】 The EAI of SPP emulsions decreased significantly from 30.3 m2?g-1 to 27.6 m2?g-1 after the addition of 0.05 mol?L-1 calcium chloride, while the d4,3 increased from 4.2 μm to 4.42 μm (P＜0.05). Nevertheless, with the further increase in concentrations of calcium chloride (0.10-0.25 mol?L-1), the EAI had no obvious difference (P＞0.05), but the d4,3 had a marked increase (P＜0.05). In addition, the CI, interfacial adsorbed protein concentration and initial apparent viscosity were increased markedly by adding higher concentrations of calcium chloride (P＜0.05). Furthermore, SDS-PAGE showed that Sporamin A was not easy to be adsorbed at oil/water interface, and that the high molecular polymers (＞66 kD) formed by S-S bonding existed both in oil/water interface and continuous phase of emulsions. 【Conclusion】 The binding of calcium ions to SPP could change its structure thereby affecting the emulsifying properties of SPP.