离子强度对亚麻籽胶-酪蛋白乳液稳定性影响

Effect of Ionic Strength on the Stability of Caseinate-stabilized Emulsions Containing Flaxseed Gum

pH值和离子强度是影响乳液稳定性的重要因素。探讨了亚麻籽胶和酪蛋白在水溶液中的相互作用,并推广到研究不同pH值和离子强度下乳液ζ-电位、粒径、微观结构、乳液黏度和界面蛋白组成等性质,揭示二者与乳液稳定性之间的关系。研究表明:pH 7条件下,未添加NaCl的乳液因亚麻籽胶的"弱凝胶性"使其在较长时间内保持稳定;随着盐浓度升高,盐离子的电荷屏蔽作用使乳液表面电势降低,乳液黏度下降,乳液内部排斥絮凝现象未得到改善,乳液稳定性下降。pH 5条件下,酪蛋白自身在等电点附近的聚集使得乳液稳定性降低;盐离子促进亚麻籽胶吸附到酪蛋白包裹的油滴表面,在乳液内形成了微观网络结构,低浓度(50 mmol/L)条件下改善乳液稳定性。

Both pH value and ionic strength are important for the stability of the emulsions.The interaction between flaxseed gum（FG） and sodium caseinate（CN） was studied by making the state diagram in aqueous solution.And then in emulsions,the possible relationship between FG-CN interaction and the stability of the emulsions were examined by measuring the ζ-potential,droplet size,microstructures,apparent viscosity and surface protein composition.At pH 7,emulsions could be stable for a long time without the addition of NaCl due to FG＇s weak gel-like properties.With the increase of NaCl,the electrostatic screening effect made the emulsion ζ-potential decreased as well as their viscosity.But their depletion flocculation was not improved,and NaCl made the samples unstable.At pH 5,emulsions without the addition of NaCl were unstable since the pH was very close to the isoelectric point of CN.NaCl helped the FG adsorb onto the surface of the droplets,and low addition（50 mmol/L） of NaCl improved the stability of the samples.