Characterization and Discrimination of the Taste and Aroma of Quinoa Baijiu Using Electronic Tongue, GC Electronic Nose and Comprehensive Two-Dimensional Gas Chromatography Time-of-Flight Mass Spectrometry

Quinoa Baijiu, brewed with quinoa as a partial or sole raw material, is an emerging distilled spirit whose flavor characteristics remain poorly characterized. This study aimed to characterize and discriminate the taste and aroma of quinoa Baijiu using electronic tongue (E-tongue), gas chromatographic electronic nose (GC E-nose) and headspace solid-phase microextraction coupled with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (HS-SPME-GC×GC-TOF-MS). Three quinoa Baijiu samples (quinoa accounting for 20%, 40% and 100% of the raw materials, QJ20, QJ40 and QJ100) were compared with nine commercial Baijiu samples covering light-, strong- and sauce-aroma types. A total of 201 volatile compounds were identified, among which 70 esters predominated (>60% of the total relative content). E-tongue analysis showed that quinoa Baijiu exhibited significantly higher sweetness-associated and lower bitterness-associated sensor responses than the commercial reference samples. These findings reflect instrumental discrimination and should not be equated with human sensory perception. GC E-nose, combined with hierarchical cluster analysis, clearly differentiated the four Baijiu categories and revealed that the instrumental aroma fingerprints of quinoa Baijiu were similar to those of light-aroma Baijiu. Compounds relatively abundant in or unique to quinoa Baijiu—including ethyl undecanoate, ethyl oleate, diethyl azelate, 1,2-decanediol, acacia alcohol, 2-ethyl heptanoic acid, 2,5-dimethyl-4-hexenoic acid, 3-methylenetridecane, 7-hexadecene and caryophyllene—may serve as candidate volatile markers. These results demonstrate that quinoa Baijiu possesses a distinctive and recognizable instrumental flavor profile, providing a chemical basis for its differentiation from traditional Baijiu.