GC–MS Profiling Reveals Ethyl Lactate’s Regulatory Role in Baijiu Aroma Development During Aging

A recent joint study between the Moutai Institute (Renhuai, China), Kweichow Zhen Distillery Co., Ltd. (Zunyi, China) and the Zunyi Institute of Products Quality Inspection and Testing (Zunyi, China) investigated the aroma of soy sauce made with baijiu, analyzing 76 base liquor samples from 15 years (2010–2024) using gas chromatography-mass spectrometry (GC–MS) to quantify 77 volatile compounds. The study also showed how multivariate analysis, molecular modeling, and sensory evaluation demonstrated that ethyl lactate can play a key regulatory role by selectively inhibiting the release of many aroma-active compounds, providing mechanistic insight to guide baijiu aging, blending, and quality control.A paper based on their research was published in Food Chemistry: X (1).

A traditional Chinese distilled liquor with unique flavor characteristics, baijiu is primarily made from sorghum (the world's fifth-most important cereal crop after rice, wheat, maize, and barley), using the yeast jiuqu as a fermentation starter (2–4). The production process involves solid-state fermentation in a semi-open environment, followed by distillation, blending, and aging (5). Aging is a critical stage in baijiu production, during which a number of complex physical and chemical changes take place, including oxidation, esterification, and hydrolysis, which transform the initial “pungent” and “harsh” flavor of the liquor into a “mellow” and “soft” profile, significantly enhancing its flavor quality of the liquor (6).

“Therefore,” write the authors in their article (1), “the aging process has a profound impact on the formation and enhancement of baijiu's flavor.”

Although the authors cite previous studies indicating that the content of many components changes significantly during Baijiu aging, this research primarily concentrated on the analysis of trends in content changes, with less attention paid to the regulatory effects of these changes on other liquor components and their corresponding impact on flavor (1).

The results of this study included the revelation that, during aging, esters generally showed a decreasing trend, while acids and alcohols increased. Combined with results of multivariate analysis, ethyl lactate was selected for further study because of its greatest absolute change in concentration. Furthermore, using headspace solid-phase microextraction combined with GC–MS demonstrated that ethyl lactate inhibits the release of 28 aroma-active compounds, with this effect varying by chemical class and being less pronounced for short-chain acids. Quantum chemical calculations revealed that this selectivity for acids is mainly attributed to their strong self-association into stable dimers, which creates a competitive inhibition against binding with ethyl lactate. Finally, sensory evaluation confirmed the effects ethyl lactate on overall flavor of the liquor (1).

“These findings,” wrote the authors of the study (1), “may provide a theoretical basis for the production, storage, design, and blending of baijiu.”

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References

1. Zhao, T.; Zhu, G.; Wu, C. et al. Variation of Aroma Compounds in Soy Sauce Aroma Type Baijiu During Aging: Focusing on the Regulatory Effect of Ethyl Lactate on Aroma Release. Food Chem. X. 2025, 33, 103396. DOI: 10.1016/j.fochx.2025.103396
2. Jin, G.; Zhu, Y.; Xu, Y. Mystery Behind Chinese Liquor Fermentation. Trends in Food Science & Technology 2017, 63, 18-28. DOI: 10.1016/j.tifs.2017.02.016
3. Awika, J. M. Major Cereal Grains Production and Use around the World; in Advances in Cereal Science: Implications to Food Processing and Health Promotion (ACS Symposium Series) 2011, 1089, 1–13. DOI:10.1021/bk-2011-1089.ch001
4. Xia, Y.; Luo, H.; Wu, Z. et al. Microbial Diversity in Jiuqu and its Fermentation Features: Saccharification, Alcohol Fermentation and Flavors Generation. Appl. Microbiol. Biotechnol. 2023, 107 (1), 25-41. DOI: 10.1007/s00253-022-12291-5
5. Fan, W.; Qian, M. C. Characterization of Aroma Compounds of Chinese “Wuliangye” and “Jiannanchun” Liquors by Aroma Extract Dilution Analysis. J. Agric. Food Chem. 2006, 54 (7), 2695-2704. DOI: 10.1021/jf052635t
6. Xu, M. L.; Yu, Y.; Ramaswamy, H. S. et al. Characterization of Chinese Liquor Aroma Components During Aging Process and Liquor Age Discrimination Using Gas Chromatography Combined with Multivariable Statistics. Sci. Rep. 2017, 7, 39671. DOI: 10.1038/srep39671