Ethanol evaporation drives ester assembly and particle deposition in droplets of Chinese distilled liquors

Abstract

Chinese distilled liquor, known as Baijiu, typically has a relatively high ethanol content (52 or 53% alcohol by volume, ABV) and is characterized by a powerful, heady scent. When its alcohol content is less than 45% ABV, Baijiu loses its flavor and becomes cloudy and tasteless; thus, it is relatively bland and thin. Since this phenomenon has not been reasonably explained, the aim of this study is to determine its underlying mechanism by examining the droplet evaporation. A 1.0 µL of droplets were applied to the substrate surface for evaporation. The results revealed that a reduction in the alcohol content (<45% ABV) triggered the self-assembly of unique long-chain fatty acid ethyl esters into various nano- or microparticles with sizes ranging from 100 nm to 10 µm within the Baijiu droplets. These particles deposit under the influence of internal flow and exhibit Baijiu-specific coffee-ring effects after drying. Interestingly, these particles encapsulated the water-soluble or insoluble flavor chemicals, resulting in the brightness and aroma/flavor of Baijiu decreased radically; this is the reason that a high alcohol content is needed in Baijiu. These findings offer new insights for the quality control of low-alcohol Baijiu and Baijiu identification.

References

[1] Zheng X-W, Han B-Z. Baijiu (白酒), Chinese liquor: history, classification and manufacture. J Ethn Foods. 2016; 3: 19-25.

[2] National Bureau of Statistics of People's Republic of China. National Data. 2021. Available online: https://data.stats.gov.cn/easyquery.htm?cn=A01&zb=A020909&sj=202306

[3] Luo H. Baijiu Brewing Techniques. 1st ed. Southwest Jiaotong University Press; 2012. (in Chinese)

[4] Liu H, Sun B. Effect of fermentation processing on the flavor of Baijiu. J Agric Food Chem. 2018; 66: 5425–5432.

[5] Jin G, Zhu Y, Xu Y. Mystery behind Chinese liquor fermentation. Trends Food Sci Technol. 2017; 63: 18–28.

[6] Hong J, Tian W, Zhao D. Research progress of trace components in sesame-aroma type of baijiu. Food Res Int. 2020; 137:109695.

[7] Yoneya T. Handbook of Food Science, Technology, and Engineering. CRC Press; 2005.

[8] Chen Z, Peng K, Xu B. Material assembly by droplet drying: from mechanics theories to applications. Droplet. 2023; 2:e76.

[9] Wu Y, Urrutia Gomez JE, Zhang H, et al. Digital twin of a droplet microarray platform: evaporation behavior for multiple droplets on patterned chips for cell culture. Droplet. 2024; 3:e94.

[10] Lohse D, Zhang X. Physicochemical hydrodynamics of droplets out of equilibrium. Nat Rev Phys. 2020; 2: 426.

[11] Deegan RD, Bakajia O, Dupont TF, et al. Capillary flow as the cause of ring stains from dried liquid drops. Nature. 1997; 389: 827-829.

[12] Sefiane K, Tadrist L, Douglas M. Experimental study of evaporating water–ethanol mixture sessile drop: influence of concentration. Int J Heat Mass Transfer. 2003; 46: 4527–4534.

[13] Yunker PJ, Still T, Lohr MA, Yodh AG. Suppression of the coffee-ring effect by shape-dependent capillary interactions. Nature. 2011; 476: 308–311.

[14] Anyfantakis M, Geng Z, Morel M, Rudiuk S, Baigl D. Modulation of the coffee-ring effect in particle/surfactant mixtures: the importance of particle-interface interactions. Langmuir. 2015; 31: 4113–4120.

[15] Rey M, Walter J, Harrer J, et al. Versatile strategy for homogeneous drying patterns of dispersed particles. Nat Commun. 2022; 13: 2840.

[16] Girard F, Antoni M, Faure S, Steinchen A. Influence of heating temperature and relative humidity in the evaporation of pinned droplets. Colloids Surf A. 2008; 323: 36–49.

[17] Li Y-F, Sheng Y-J, Tsao H-K. Evaporation stains: suppressing the coffee-ring effect by contact angle hysteresis. Langmuir. 2013; 29: 7802–7811.

[18] Moore MR, Wray AW. Gravitational effects on coffee-ring formation during the evaporation of sessile droplets. J Fluid Mech. 2023; 967: A26.

[19] Zang D, Sujata T, Tarasevich YY, Choudhury MD, Dutta T. Evaporation of a droplet: from physics to applications. Phys Rep. 2019; 804: 1–56.

[20] Kim H, Boulogne F, Um E, et al. Controlled uniform coating from the Interplay of marangoni flows and surface-adsorbed macromolecules. Phys Rev Lett. 2016; 116:124501.

[21] Carrithers AD, Brown MJ VI, Rashed ZM, et al. Multiscale self-assembly of distinctive weblike structures from evaporated drops of dilute american whiskeys. ACS Nano. 2020; 14: 5417–5425.

[22] Tan H, Diddens C, Lv P, Lohse D. Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop. Proc Natl Acad Sci USA. 2016; 113: 8642–8647.

[23] Williams SJ, Islam S, Velev OD. Light scattering of colloidal suspensions: formation and stability in bourbon whiskeys. J Inst Brew. 2022; 128: 66–72.

[24] Gelderblom H, Diddens C, Marin A. Evaporation-driven liquid flow in sessile droplets. Soft Matter. 2022; 18: 8535–8553.

[25] Wu Y, Chen H, Huang H, et al. Revelation for the influence mechanism of long-chain fatty acid ethyl esters on the Baijiu quality by multicomponent chemometrics combined with modern flavor sensomics. Foods. 2023; 12: 1267.

[26] Li J, Zhang Q, Sun B. Chinese Baijiu and whisky: research reservoirs for flavor and functional food. Foods. 2023; 12: 2841.

[27] Israelachvili JN, Mitchell DJ, Ninham BW. Theory of self-assembly of hydrocarbon amphiphiles into micelles and bilayers. J Chem Soc Faraday Trans 2 Mol Chem Phys. 1976; 72: 1525-1568.

[28] Tanford C. Micelle shape and size. J Phys Chem. 1972; 76: 3020-3024.

[29] Griffin WC. Calculation of HLB values of non-ionic surfactants. Am Perfumer Essent Oil Rev. 1954; 6565: 26-29.

[30] Sitnikova NL, Sprik R, Wegdam G, Eiser E. Spontaneously formed trans-anethol/water/alcohol emulsions: mechanism of formation and stability. Langmuir. 2005; 21: 7083–7089.

[31] Vratsanos MA, Xue W, Rosenmann ND, Zarzar LD, Gianneschi NC. Ouzo effect examined at the nanoscale via direct observation of droplet nucleation and morphology. ACS Cent Sci. 2023; 9: 457–465.

[32] Liu Y-M, Wu Z-Q, Bao S, et al. The possibility of changing the wettability of material surface by adjusting gravity. Research. 2020; 2020:2640834.

[33] Parsa M, Harmand S, Sefiane K. Mechanisms of pattern formation from dried sessile drops. Adv Colloid Interface Sci. 2018; 254: 22–47.

[34] Wu M, Man X, Doi M. Multi-ring deposition pattern of drying droplets. Langmuir. 2018; 34: 9572–9578.

[35] Zhang W, Yu T, Liao L, Cao Z. Ring formation from a drying sessile colloidal droplet. AIP Adv. 2013; 3:102109.

[36] Shen X, Ho CM, Wong TS. Minimal size of coffee ring structure. J Phys Chem B. 2010; 114: 5269–5274.

[37] Majumder M, Rendall CS, Eukel JA, et al. Overcoming the “coffee-stain” effect by compositional marangoni-flow-assisted drop-drying. J Phys Chem B. 2012; 116: 6536–6542.

[38] Bhardwaj R, Fang X, Somasundaran P, Attinger D. Self-assembly of colloidal particles from evaporating droplets: role of DLVO interactions and proposition of a phase diagram. Langmuir. 2010; 26: 7833–7842.

[39] Sefiane K. On the role of structural disjoining pressure and contact line pinning in critical heat flux enhancement during boiling of nanofluids. Appl Phys Lett. 2006; 89:044106.

[40] Orejón D. A Study of Nanosuspension Droplets Free Evaporation and Electrowetting. PhD thesis. University of Edinburgh; 2013.

[41] Zhong X, Duan F. Flow regime and deposition pattern of evaporating binary mixture droplet suspended with particles. Eur Phys J E Soft Matter. 2016; 39: 18.

[42] Bennacer R, Sefiane K. Vortices, dissipation and flow transition in volatile binary drops. J Fluid Mech. 2014; 749: 649–665.

[43] Christy JRE, Hamamoto Y, Sefiane K. Flow transition within an evaporating binary mixture sessile drop. Phys Rev Lett. 2011; 106:205701.

[44] Shanahan MER. Simple theory of “stick-slip” wetting hysteresis. Langmuir. 1995; 11: 1041–1043.

[45] Boothroyd EL, Linforth RST, Cook DJ. Effects of ethanol and long-chain ethyl ester concentrations on volatile partitioning in a whisky model system. J Agric Food Chem. 2012; 60: 9959-9966.

[46] Shen Y. Technical Book of Baijiu Production. 1st ed. China Light Industry Press; 2022. (in Chinese)

[47] Huang H, Wu Y, Chen H, et al. Identification of regionalmarkers based on the flavor molecular matrix analysis of sauce-aroma style Baijiu. J Sci Food Agric. 2023; 103: 7434–7444.

RIGHTS & PERMISSIONS

2025 The Author(s). Droplet published by Jilin University and John Wiley & Sons Australia, Ltd.