Abstract: In order to provide basic theoretical data for the healthy development of Chinese liquor (Baijiu), we studied the molecular mechanism of the interactions between collagen peptides and four aldehydes in Chinese liquor, furfural, benzaldehyde, acetaldehyde and isovaleraldehyde using ultraviolet-visible (UV-vis) spectroscopy, fluorescence spectroscopy and three-dimensional fluorescence spectroscopy. UV-vis absorption spectra indicated that the intensity of the absorption peak of collagen polypeptide at 198 nm was increased with increasing concentrations of furfural and benzaldehyde. Meanwhile, there was no significant change with acetaldehyde and isovaleraldehyde at lower concentrations. However, the absorption intensity was increased at higher concentrations of acetaldehyde and isovaleraldehyde, and new absorption peaks with increasing intensity were generated at wavelengths of about 280 nm and 290 nm respectively. Furthermore, fluorescence spectral analysis corroborated that all four aldehydes had obvious fluorescence quenching on collagen peptides, statically for furfural and benzaldehyde, and dynamically for acetaldehyde and isovaleraldehyde. Thermodynamic calculation revealed that furfural and benzaldehyde bound to collagen peptides predominately by hydrophobic interaction with about one binding site; the binding process was spontaneous. In addition, three-dimensional fluorescence spectral analysis suggested that the binding?strengths between the four aldehydes and collagen peptide decreased in the order of furfural > benzaldehyde > isovaleraldehyde > acetaldehyde. Finally, the results of headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) analysis showed that collagen peptide could reduce the content of aldehydic components in strong-flavor Chinese Baijiu.

Key words: collagen peptides; Chinese liquor (Baijiu); aldehyde; spectral analysis; interaction mechanism