Key Aroma Compounds Analysis of Strong-Aroma Baijiu Based on 6 Extraction Methods of Molecular Sensory Science and GC × GC-O-TOF MS

The strong-aroma Baijiu is widely favored among consumers due to its elegant cellar aroma, harmonious bouquet, clean mouthfeel, and lingering aftertaste. However, many aroma compounds are difficult to fully extract and analyze because of their low concentration and varying polarities. Based on molecular sensory science, sensory evaluation combined with multiple extraction techniques (including solid phase micro-extraction, stir bar sorptive extraction, dynamic headspace sampling, liquid-liquid extraction, direct injection, and MonoTrap) and comprehensive two-dimensional gas chromatography-olfactory-time-of-flight mass spectrometry were employed to systematically extract and identify the key aroma-active compounds in Touqu-Baijiu (a typical representative of strong-aroma Baijiu). Sensory evaluation revealed that Touqu-Baijiu exhibited prominent cellar, alcoholic, fruity, sweet, and acidic aromas, with the cellar aroma being the most pronounced. A total of 311 aroma compounds were identified, among which 133 were aroma-active compounds, and 49 compounds with high flavor dilution factors were precisely quantified and their odor activity values were calculated. Through aroma recombination and omission experiments, ethyl hexanoate, ethyl acetate, ethyl butyrate, ethyl lactate, hexanoic acid, ethyl pentanoate, ethyl heptanoate, hexanal, phenylacetaldehyde, and butyric acid were confirmed as the key aroma-active compounds in Touqu-Baijiu. This study aimed to provide theoretical guidance and methodological reference for elucidating the chemical basis of the aroma profile of Touqu-Baijiu as weu as for aroma analysis of Baijiu and other alcoholic beverages.