Decoding off-odour profiles of six typical defective sauce-flavour Baijiu by integrating multidimensional detection and molecular docking

Flavour imbalance significantly impairs sauce-flavour Baijiu quality; however, the key off-odour compounds remain unclear. Multidimensional detection and molecular docking were employed to explore the flavour profiles of six typical defective off-odour sauce-flavour Baijiu samples (mud-like, green, rancid-like, pickle-like, oil-like and burnt). Quantitative sensory analysis showed defective samples featured unique off-odours and varied from normal ones in sauce-flavour Baijiu aroma. E-nose analysis revealed that mud-like off-odour most significantly differed from normal Baijiu, followed by oil-like and green off-odours, whereas rancid-like, pickle-like and burnt off-odours exhibited minor differences. Meanwhile, 73 and 134 volatiles were detected via gas chromatography-mass spectrometry and gas chromatography-ion mobility spectrometry, respectively, with 14 recurring compounds. Chemometrics identified 61 differential compounds between off-odour and normal samples, and 34 potentially off-odour contributors were screened by odour activity value and relative odour activity value. Molecular docking emphasised key compounds associated with each off-odour, such as 1-octene for mud-like, ethyl octanoate for green, naphthalene for rancid-like, p-dichlorobenzene for pickle-like, butyl 2-methylbutyrate for oil-like and ethyl 3-methylbutanoate for burnt off-odours. These compounds primarily form stable conformations with receptors through hydrophobic interactions, causing odor perception. This study provides systematic insights into the typical off-odour of sauce-flavour Baijiu, forming a basis for its quality refinement. • Combined E-nose, GC–MS, and GC–IMS characterized off-odour sauce-flavour Baijiu. • The off-odour of sauce-flavour Baijiu were induced by flavour compound imbalance. • Sixteen key differential compounds identified in six defective sauce-flavour Baijiu. • Hydrophobic binding of off-odourants to olfactory receptors drives odour perception.