Abstract: Heat-induced polymerized whey protein (PWP) gels from whey protein isolate have limited application due to their high brittleness, but addition of polysaccharides in PWP gels can significantly improve their properties. Agaricus bisporus polysaccharide (ABP), as an anionic polysaccharide, exhibits excellent biological activities, but the formation mechanism of its composite hydrogels with PWP remains unclear. In this study, the effect of ABP concentration (0–4 g/100 mL) was investigated on physicochemical properties of PWP-ABP composite hydrogels including average particle size, zeta potential, surface hydrophobicity, intrinsic fluorescence spectrum and free sulfhydryl group content. The results demonstrated that as the ABP concentration increased, the average particle size of PWP-ABP composite hydrogels significantly increased from (76.22 ± 7.43) to (145.93 ± 8.20) nm (P < 0.05), and the absolute value of zeta potential rose from (35.60 ± 2.64) to (45.20 ± 1.40) mV, indicating that ABP enhanced the stability of the composite hydrogels through electrostatic repulsion. Additionally, the surface hydrophobicity decreased remarkably, and the free sulfhydryl group content significantly decreased (P < 0.05), confirming that ABP altered the tertiary structure of PWP via hydrophobic interactions and disulfide bond crosslinking. Synchronous rheology-Fourier transform infrared spectroscopy analysis revealed that ABP induced a red shift in the amide A region (3 600–3 200 cm-1) of PWP, suggesting enhanced hydrogen bond formation; the fluctuations in the amide I band (1 625 cm-1) were attributed to electrostatic interactions. Molecular docking analysis showed that ABP binds to β-lactoglobulin via hydrogen bonds and two-dimensional correlation spectroscopy further validated the changes in O–H stretching vibrations. In conclusion, ABP optimizes the gel network structure of PWP through hydrophobic interactions, hydrogen bonds and electrostatic interactions, providing a theoretical foundation for developing functional food gel systems.

Key words: Agaricus bisporus polysaccharide; polymerized whey protein; simultaneous rheology-Fourier transform infrared spectroscopy; two-dimensional correlation spectroscopy; molecular docking

摘要： 热诱导乳清分离蛋白形成的聚合乳清蛋白（polymerized whey protein，PWP）凝胶因脆性高而应用受限，而多糖的添加可显著改善其性能。双孢菇多糖（Agaricus bisporus polysaccharide，ABP）作为一种阴离子多糖，具有优异的生物活性，但其与PWP的复合水凝胶形成机制尚不明确。本研究通过测定PWP-ABP复合水凝胶的平均粒径、Zeta电位、表面疏水性、内源荧光光谱及表面游离巯基含量等，揭示ABP质量浓度（0～4 g/100 mL）对PWP理化特性的影响。结果表明，随着ABP含量的增加，PWP-ABP复合水凝胶平均粒径从（76.22±7.43）nm显著增至（145.93±8.20）nm（P＜0.05），Zeta电位绝对值从（35.60±2.64）mV升至（45.20±1.40）mV，表明ABP可通过静电斥力增强复合水凝胶稳定性。同时，随着ABP含量的增加，复合水凝胶表面疏水性显著下降，表面游离巯基含量显著降低（P＜0.05），证实ABP能够通过疏水相互作用与二硫键交联改变PWP三级结构。进一步采用同步流变学-傅里叶变换红外光谱技术追踪水凝胶在加热过程中的结构变化发现，ABP促使PWP中酰胺A带（3 600～3 200 cm－1）吸收峰红移，表明氢键形成增强；酰胺I带（1 625 cm－1）波动则归因于静电作用。分子对接分析显示，ABP通过氢键与β-乳球蛋白结合，二维相关光谱进一步验证O—H伸缩振动的变化。综上，ABP可通过疏水相互作用、氢键及静电作用优化PWP水凝胶网络结构，本研究结果可为开发功能性食品凝胶体系提供理论依据。

关键词: 双孢菇多糖；聚合乳清蛋白；同步流变学-傅里叶变换红外光谱；二维相关光谱；分子对接