为了探究pH值和质量比对多糖和CN之间相互作用的影响，选取两种天然多糖，分别与酪蛋白（CN）以不同质量比进行混合，测定多糖和CN复合体系在不同pH值条件下的理化指标、微观结构和红外光谱。结果表明：不同质量比的海藻酸钠（SA）与CN的复合物电位绝对值均大于30 mV，pH值为4.0时CN和SA质量比为1:3的电位绝对值最大为57 mV，随着pH值的增加，绝对值减少；不同质量比的瓜尔豆胶（GG）与CN的复合体系电位绝对值均低于30 mV，随着pH值的增加，绝对值增加，不同质量比之间没有显著差别；CN-SA复合体系表面疏水性指数S0低于35，CN-GG复合体系S0低于50；由红外光谱图得出SA与CN之间以静电相互作用为主，而GG通过镶嵌在CN的网络结构中起到稳定CN的作用，主要是通过氢键与CN发生作用。两种天然多糖与CN之间的相互作用受到pH值和质量比的影响，远离CN等电点的pH值范围以及添加3倍质量的SA或等量的GG可以使含CN体系在酸性条件更均一稳定，可以为提高含CN的食品饮料体系的质构稳定性提供理论支撑。

In order to explore the influence of pH value and mass ratio on the interaction between polysaccharide and CN, two kinds of natural polysaccharides were selected and mixed with casein (CN) at different mass ratios, respectively. The physicochemical indexes, microstructure and infrared spectra of polysaccharide and CN composite systems at different pH values were determined. The results show that: The absolute value of complex potential of sodium alginate (SA) and CN with different mass ratios is greater than 30 mV. When pH is 4.0, the maximum absolute value of potential is 57 mV when the mass ratio of CN and SA is 1:3, and the absolute value decreases with the increase of pH. The absolute value of complex potential of GG and CN was lower than 30 mV, and the absolute value increased with the increase of pH, and there was no significant difference between different mass ratios. The surface hydrophobicity index S0 of the CN-SA composite system was lower than 35, and that of the CN-GG composite system was lower than 50. According to the infrared spectra, the interaction between SA and CN is mainly electrostatic, while GG plays a role in stabilizing CN by embedding in the network structure of CN, and mainly interacts with CN through hydrogen bonding. The interaction between the two natural polysaccharides and CN is affected by pH value and mass ratio. The pH range away from the isoelectric point of CN and the addition of 3 times the mass of SA or equal amount of GG can make the CN system more uniform and stable in acidic conditions. It can provide theoretical support for improving the texture stability of food and beverage system containing CN.

湖南省自然科学基金面上项目(2021JJ30660)；广东省天然产物绿色加工与产品安全重点实验室开放(201610)