Extensive “Heart-Cut” 2D GC-MS/Olfactometry, Complementary to Aroma Extract Dilution Analysis, Odor Activity Value Evaluation, and Aroma Recombination Study, to Assess the Contribution of “Five-Grain” Derived Compounds to Baijiu Aroma

Grains are widely used for the fermentation of spirits, including baijiu. Wuliangye is one of the most renowned baijiu brands, fermented from a blend of five grains: sorghum, wheat, corn, rice, and glutinous rice. To understand the aroma contribution of the raw grains to the product quality, the aroma compounds of “five-grain” were comprehensively investigated by aroma extract dilution analysis (AEDA), “heart-cut” 2D gas chromatography–mass spectrometry/olfactometry (2D GC-GC-MS/O), and comprehensive gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS). Thirty-four aroma-active compounds identified in the grains, primarily aldehydes, were further investigated using odor activity values (OAVs), aroma recombination, and omission studies. The results demonstrated that (E,E)-2,4-decadienal, 2-acetyl-1-pyrroline, (E,Z)-2,6-nonadienal, (E)-2-nonenal, (E,E)-2,4-nonadienal, trans-4,5-epoxy-2(E)-decenal, hexanal, and methional were the compounds in “five-grain” important to baijiu aroma. Understanding the origin and fate of these compounds will aid in further research and quality control of this renowned baijiu brand.