Comparative Interaction Mechanisms and Solution Behavior of Cowhide Collagen with Xanthan Gum, Gellan Gum, and Chitosan Under Variable Environmental Conditions

Cowhide collagen (CC) is a valuable by-product of the meat industry with promising applications in food systems; however, its poor viscosity and limited stability restrict its practical use. This study systematically investigated the interactions between CC and three representative polysaccharides-xanthan gum (XG), gellan gum (GG), and chitosan (CS)-under varying concentrations, pH, and ionic strengths. The physicochemical behaviors of the composite systems were evaluated through turbidity, fluorescence spectroscopy, Fourier transform infrared (FTIR) analysis, and rheological measurements. The experimental results revealed a pronounced increase in the turbidity of the GG-CC system, rising from approximately 0.18 ± 0.01 to 2.14 ± 0.01 as the polysaccharide concentration increased, with maximum values exceeding 2.0 under several conditions. Similarly, both the apparent viscosity and turbidity of the other two PS-CC composite systems exhibited a marked and progressive enhancement with increasing polysaccharide content. FTIR spectra confirmed strengthened O-H stretching and amide I shifts, indicating intensified hydrogen bonding and electrostatic interactions. High NaCl levels disrupted the protein hydration shell, modifying fluorescence intensity and peak sharpness. XG-CC and GG-CC composites exhibited similar behaviors, while CS-CC systems showed opposite pH-dependent trends due to cationic-cationic repulsion. Overall, polysaccharide type and concentration exerted stronger effects on CC structure and rheology than environmental factors. These results clarify how polysaccharide type and environmental factors modulate collagen-polysaccharide interactions and provide practical guidance for selecting polysaccharides and processing conditions to tailor the rheological and stability properties of collagen-based food ingredients.