Abstract: To investigate the mechanism by which swelling treatment improves the quality of boneless chicken feet, this study systematically analyzed the dynamic changes in collagen content and structure during swelling. The physicochemical properties and texture of chicken feet were analyzed after swelling and marination. Collagen was extracted at different swelling ratios (0%–50%) using an acid-enzyme combination method, and its structure was characterized by scanning electron microscopy (SEM), ultraviolet (UV), Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), and lowfield nuclear magnetic resonance (LF-NMR) spectroscopy. The results showed that after swelling and marination, the moisture content and L* value of chicken feet increased initially and then decreased, while the centrifugal loss increased significantly. The shear force, hardness, and chewiness decreased significantly, whereas the springiness increased notably (P < 0.05). Swelling treatment (at 30 ℃ and pH 3.2 for 6 h) significantly decreased the content of total collagen and insoluble collagen, while increasing the content and solubility of soluble collagen (P < 0.01). SEM revealed that the fibrous network changed from a dense structure to a loose, porous, denatured morphology. UV and FTIR spectra further confirmed conformational changes in collagen molecules, along with the formation of a strengthened hydrogenbond network. CD analysis showed a red shift of the negative absorption peak, indicating partial relaxation or unwinding of the triplehelix structure, which provided more binding sites for water molecules. Moreover, surface hydrophobicity peaked at a 30% swelling ratio, and LF-NMR confirmed a significant increase in water content after swelling, indicating enhanced water retention capacity. In summary, swelling treatment can simultaneously improve water absorption, water retention, and tenderness by inducing multiscale synergistic changes in collagen, such as forming a porous structure, relaxing molecular conformation, and strengthening hydrogen bonding. These findings provide a theoretical foundation for the precise optimization of processing technologies aimed at increasing the added value of boneless chicken claws products.

Key words: boneless chicken feet; collagen; swelling treatment; hydrogen bond reconstruction; textural properties; hydration characteristics