Effect of pH Value and Mass Ratio on Interaction between Casein and Two Natural Polysaccharides

HUA Shuyu; HUI Danyang; WEN Haitao; ZHOU Rong; LIU Zhongyi

doi:10.13982/j.mfst.1673-9078.2026.1.1597

Abstract：Two types of natural polysaccharides were selected and mixed with CN at different mass ratios to explore the influence of pH value and mass ratio on the interaction between polysaccharide and casein(CN).The physicochemical indices,microstructure,and infrared spectra of polysaccharide and CN composite systems at various pH values were determined.The results showed that the absolute value of the complex potential of sodium alginate(SA)and CN with different mass ratios is greater than 30 mV.At pH 4.0,the maximum absolute potential value(57 mV)was observed when the mass ratio of CN and SA was 1:3,and the absolute value decreased with increasing pH.The absolute value of the complex potential of guar gum(GG)and CN was lower than 30 mV,and the absolute value increased with the increase of pH.Additionally,there was no significant difference between different mass ratios.The surface hydrophobicity index S0 of the CN-SA composite system was<35,and that of the CN-GG composite system was<50.According to infrared spectra,the interaction between SA and CN is primarily electrostatic,while GG plays a role in stabilizing CN by embedding in the network structure of CN,and interacts with CN primarily through hydrogen bonding.The interaction between the two natural polysaccharides and CN is affected by pH value and mass ratio.A pH range far from the isoelectric point of CN and the addition of a three-fold amount of SA or an equivalent amount of GG can enhance the uniformity and stability of the CN system under acidic conditions.These findings provide theoretical support for improving the texture stability of food and beverage systems containing CN.