Freshly distilled Chinese Baijiu is famously harsh, with pungent, rough flavors that only soften after years of storage. A new study published in Food Chemistry: X has mapped, compound by compound, how the aroma of Jiangxiangxing (JXX) Baijiu transforms over two decades of aging, and it is the first to systematically track these changes across all seven brewing rounds of the spirit’s base liquor. By combining targeted molecular sensoryomics with untargeted flavoromics, researchers identified dozens of odorants that rise or fall during storage, then confirmed their roles through aroma recombination and omission experiments with a trained sensory panel.

Each batch included samples aged for 0, 5, 10, 15, and 20 years, with the youngest distilled in 2024. This design matters because JXX Baijiu is produced through seven distinct brewing rounds, each with its own sensory fingerprint: the first two rounds carry pronounced grain, sour, and fruity aromas; rounds three through five show floral, grassy, sauce, Daqu, and pasty notes; and rounds six and seven present strong pasty and Daqu aromas with bitterness and a long aftertaste. Previous work on aging in this spirit had covered only the first four rounds.

The analytical strategy paired two complementary approaches. On the targeted side, the researchers used pH-controlled liquid-liquid extraction to split each sample into acidic, basic, neutral, and water-soluble fractions, then ran comparative aroma extract dilution analysis on a gas chromatograph fitted with an olfactory detection port. Three trained panelists recorded aroma attributes and intensities in real time, and flavor dilution factors were calculated from serial two-fold dilutions. On the untargeted side, volatile and semi-volatile compounds were profiled by headspace solid-phase microextraction and liquid-liquid microextraction coupled to GC-MS, with principal component analysis and Pearson correlation linking chemical shifts to storage time.

The GC-O analysis detected 167 aroma-active peaks, of which 138 compounds were identified. In the 20-year samples, the odorants with the highest flavor dilution factors, at 256 or above, included ethyl acetate, 2-ethyl-6-methylpyrazine, 2,3,5,6-tetramethylpyrazine, benzaldehyde, 2-formylpyrrole, 2-acetylpyrrole, HDMF, sotolone, phenylacetic acid, and vanillin. Three compounds, alpha-(2-furanylmethylene)benzeneacetaldehyde with floral, medicinal, and smoky notes, ethyl nicotinate with a corn-like aroma, and 2-nonen-4-one with a steamed grain aroma, were reported in JXX Baijiu for the first time. After aging, floral, fruity, and pungent aromas diminished, while roasted, nutty, and sauce-like aromas intensified, and new grainy and smoky notes appeared.

Comparing young and aged samples, the team found 27 compounds whose flavor dilution factors rose at least eight-fold across three or more rounds, and 20 compounds that fell by the same margin. The untargeted flavoromics analysis identified 124 flavor compounds overall, including 36 esters, 27 aldehydes, 14 alcohols, and 4 pyrazines. Across all rounds, compounds with significant decreases outnumbered those with increases, with most changes in the 2-to-10-fold range. Ester content dropped by 1.1 to 25.5 percent depending on the round, while acids rose by 0.6 to 14.3 percent, consistent with ester hydrolysis. Furans, pyrazines, and ketones trended upward, enriching the spirit’s roasted character.

Statistical modeling sharpened the picture. Of the 124 compounds, 96 passed normality and variance tests, and two-way mixed-model ANOVA revealed significant main effects of aging time on 89 of them and of brewing round on 76. Principal component analysis showed that the first two components explained 43.55 percent of flavor variance, and all samples shifted directionally along both axes from year 0 to year 20, with dispersion between rounds shrinking over time. The researchers divided storage into two stages: a rapid change period from year 0 to year 10, during which flavor transformations were intense, and a stabilization period from year 10 to year 20, during which the flavor system gradually reached equilibrium.

Quantitation and odor activity value analysis narrowed the field to 25 compounds with regular concentration changes across all seven rounds, 16 increasing and 9 decreasing, proposed as chronological markers of JXX Baijiu aging. Among the rising compounds, 3-hydroxy-2-butanone, benzaldehyde, and furfural increased linearly, with significant aging-time effects and significant gains after 10 years of storage. Vanillin, ethyl vanillate, and 4-hydroxyphenylacetic acid also accumulated significantly from year 10 onward, likely through lignin degradation and oxidation. Sotolone, gamma-valerolactone, and 3-methyl-2(5H)-furanone rose progressively, while monoethyl succinate, rarely reported in Baijiu literature, showed round-dependent accumulation rates beginning at year 5. On the declining side, acetic acid fell from year 5 onward, fusel alcohols such as 1-propanol, 1-butanol, and 2-methyl-1-propanol dropped markedly, and the off-note compounds 4-ethylphenol and dimethyl trisulfide decreased non-linearly, attributed to evaporation, oxidation, and adsorption by ceramic jars.

Odor activity values, calculated from thresholds measured in 53 percent ethanol-water solution, revealed which compounds actually dominate perception. In young liquor, the top contributors were ethyl isovalerate with odor activity values of 1190 to 3194 and an apple-like note, dimethyl trisulfide with values of 230 to 3369 and a pickled cabbage character, and ethyl butyrate with values of 710 to 1330, all driving the harsh, fruity profile of new spirit. In 20-year liquor, the key contributors shifted to 3-hydroxy-2-butanonone’s creamy character at values of 307 to 656, the citrus-like (E,E)-2,4-decadienal at 137 to 433, and caramel-like sotolone at 15 to 56, which underpin the aged aroma.

To verify function rather than mere correlation, the researchers built addition models. Model A spiked young fourth-round liquor with 11 rising compounds at concentrations found in 20-year samples; Model B added 8 declining compounds to aged liquor at their young-liquor levels. Model A’s aroma profile matched aged liquor with 84.97 percent similarity, showing enhanced medicinal, bakery, floral, grassy, caramel, and acidic aromas, greater richness and harmony, and reduced pungency. Model B did the reverse: adding the declining compounds to aged liquor increased pungency, weakened roasted, caramel, acidic, and fruity notes, and significantly diminished the aging aroma.

Omission experiments using triangle tests with 20 trained panelists then isolated the indispensable players. Removing benzaldehyde, valeric acid, sotolone, 1-propanol, or dimethyl trisulfide from the models produced highly significant differences, as did omitting furfural, butyric acid, monoethyl succinate, vanillin, 2-ethyl-6-methylpyrazine, ethyl acetate, 2-furfuryl alcohol, and isobutanol. Notably, monoethyl succinate and 2-furfuryl alcohol were confirmed for the first time as aroma contributors to Baijiu aging, while benzaldehyde and furfural were newly identified as key aging-related odorants in JXX Baijiu specifically. The authors conclude that compounds which decrease during storage play a role as important as those that accumulate, mitigating off-notes and pungency through volatile loss while generating secondary flavor compounds via hydrolysis and oxidation. Future work, they note, should clarify the formation and transformation pathways of these odorants to support scientifically grounded aging-acceleration strategies.

Subject of Research: Chemical and sensory profiling of odorant changes during the aging of Jiangxiangxing Baijiu base liquor across seven brewing rounds

Article Title: Decoding aroma evolution in Jiangxiangxing Baijiu: Targeted and untargeted profiling of key odorants during the aging process of seven batches of base liquor

Article References: Cao, N., Yang, Y., Zhou, S., Fu, F., Zhang, B., Liu, X., Yang, L., Xiang, P., & Yang, F. (2026). Decoding aroma evolution in Jiangxiangxing Baijiu: Targeted and untargeted profiling of key odorants during the aging process of seven batches of base liquor. Food Chemistry: X, 40, Article 104682. https://doi.org/10.1016/j.fochx.2026.104682

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104682

Keywords: Baijiu, Jiangxiangxing Baijiu, food chemistry, aroma compounds, aging, gas chromatography-olfactometry, flavoromics, odor activity value, sensory panel, ester hydrolysis, pyrazines, sotolone