Recent Advances in Exopolysaccharide–Protein Interactions in Fermented Dairy- and Plant-Based Yogurts: Mechanisms, Influencing Factors, Health Benefits, Analytical Techniques, and Future Directions

Fermented dairy- and plant-based yogurts (FDPYs) are globally valued for their nutritional and functional properties, primarily attributed to interactions between exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) and proteins. Although considerable progress has been made in understanding EPS–protein interactions, comprehensive insights into their underlying mechanisms and influencing factors remain limited. This review summarizes common protein types and EPS categories in FDPYs, and explores the interaction mechanisms, including electrostatic interactions, hydrogen bonding, hydrophobic interactions, and associated structural changes and binding behaviors. Key influencing factors such as molecular structure, pH, and temperature are also discussed. In addition, the review highlights the physiological activities of EPS–protein complexes (e.g., antioxidative and anti-inflammatory effects), their interaction with gut microbiota, and the classical analytical techniques employed to investigate these complexes (e.g., circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM)). Finally, future research directions—such as exploring molecular mechanisms and structure-function relationships—are proposed, providing a theoretical foundation for the formulation optimization and process control of functional FDPYs.