Abstract: To gain in-depth insight into the mechanisms and molecular pathways of physicochemical transformation in duck skin during high-temperature roasting, this study systematically analyzed the changes in hardness, toughness, chewiness, water distribution, and aroma characteristics in the skin of Beijing roast duck during the roasting process by texture profile analysis, low-field nuclear magnetic resonance (LF-NMR) spectroscopy, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), molecular docking and dynamics simulation. The results showed that as roasting time was prolonged, the hardness, toughness and chewiness of duck skin significantly increased; the proportion of free water content decreased while the proportion of bound water increased; the aroma profile changed notably as well. Correlation analysis revealed that these changes were mainly associated with changes in sugar components. Specifically, glycosaminoglycan content showed a positive correlation with the volume ratio of duck skin and the content of bound collagen. Furthermore, Fourier transform infrared spectroscopy (FTIR) identified the structural evolution of sulfate groups in glycosaminoglycans in duck skin during the roasting process. Computational modeling of the interaction between glycosaminoglycans with varying degrees of sulfation and collagen showed that structural modifications of glycosaminoglycans enhanced the number of their interaction sites with collagen, thereby promoting the formation of a thermally swollen cross-linked network.

Key words: roast duck skin, glycosaminoglycans, collagen, thermal swelling effect, molecular dynamics simulation