Wine chemistry
Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 4.
Types of natural molecules present in wine
- Acids in wine
- Phenolic compounds in wine
- Proteins in wine
- Sugars in wine
- Yeast assimilable nitrogen
- Minerals
- Dissolved gas (CO2)
- Monoterpenes[1] and sesquiterpenes[2] such as linalool and α-terpineol[3]
- Glutathione (reduced and oxidized)[4][5]
Volatiles
- Methoxypyrazines
- Esters : Ethyl acetate is the most common ester in wine, being the product of the most common volatile organic acid — acetic acid, and the ethyl alcohol generated during the fermentation.
- Norisoprenoids, such as C13-norisoprenoids found in grape (Vitis vinifera)[6] or wine,[7] can be produced by fungal peroxidases[8] or glycosidases.[9]
Other molecules found in wine
Conservatives
- Ascorbic acid is used during wine making
- Sulfur dioxide (SO2), a preservative often added to wine
Fining agents
Gum arabic has been used in the past as fining agent.[10]
List of additives permitted for use in the production of wine under EU law:
| Type or purpose of addition | Permitted additives |
|---|---|
| Acidification | tartaric acid |
| Clarification | calcium alginate potassium alginate |
| Decolourants | polyvinyl-polypyr-rolidone (PVPP) activated charcoal |
| Deacidification | lactic bacteria neutral potassium tartrate |
| Deodorant | copper sulfate |
| Elaboration | oak chips metatartaric acid |
| Enrichment | concentrated grape must rectified concentrated grape must |
| Enzymes | betaglucanase pectolytics |
| Fermentation | fresh lees ammonium bisulphite |
| Sequestrants | fresh lees potassium ferrocyanide |
| Stabilisation | calcium tartrate potassium bitartrate |
Others
- Melatonin[11]
- Wine lactone
- Anthocyanone A, a degradation product of malvidin under acidic conditions
Wine faults
A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine but at insufficient concentrations to adversely affect it. However, when the concentration of these compounds greatly exceeds the sensory threshold, they replace or obscure the flavors and aromas that the wine should be expressing (or that the winemaker wants the wine to express). Ultimately the quality of the wine is reduced, making it less appealing and sometimes undrinkable.[12]
The yeast Brettanomyces produces an array of metabolites when growing in wine, some of which are volatile phenolic compounds. Brettanomyces converts p-coumaric acid to 4-vinylphenol via the enzyme cinnamate decarboxylase.[13] 4-Vinylphenol is further reduced to 4-ethylphenol by the enzyme vinyl phenol reductase. 4-Ethylphenol causes a wine fault at a concentration of greater than 140 µg/L. Other compounds produced by Brettanomyces that cause wine faults include 4-ethylguaiacol and isovaleric acid.
Coumaric acid is sometimes added to microbiological media, enabling the positive identification of Brettanomyces by smell.
Geraniol is a by-product of the metabolism of sorbate and, thus, is a very unpleasant contaminant of wine if bacteria are allowed to grow in wine.
Fusel alcohols are a mixture of several alcohols (chiefly amyl alcohol) produced as a by-product of alcoholic fermentation.
See also
Notes
- ↑ Monoterpenes in grape juice and wines. M. Jiménez, Journal of Chromatography A, Volume 881, Issues 1–2, 9 June 2000, Pages 557–567, doi:10.1016/S0021-9673(99)01342-4
- ↑ Terpenes in the aroma of grapes and wines: A review. J. Marais, S. Afr. J. Enol. Vitic., 1983, volume 4, number 2, pages 49-58 (article)
- ↑ Inhibition of the decline of linalool and α-terpineol in muscat wines by glutathione and N-acetyl-cysteine. Papadopoulou D. and Roussis I. G., Italian journal of food science, 2001, vol. 13, no4, pages 413-419, INIST:13441184
- ↑ Using LC-MSMS To Assess Glutathione Levels in South African White Grape Juices and Wines Made with Different Levels of Oxygen. Wessel Johannes Du Toit, Klemen Lisjak, Maria Stander and Dersiree Prevoo, J. Agric. Food Chem., 2007, Vol. 55, No. 8, doi:10.1021/jf062804p
- ↑ Straightforward Method To Quantify GSH, GSSG, GRP, and Hydroxycinnamic Acids in Wines by UPLC-MRM-MS. Anna Vallverdú-Queralt, Arnaud Verbaere, Emmanuelle Meudec, Veronique Cheynier and Nicolas Sommerer, J. Agric. Food Chem. 2015, 63, 142−149, doi:10.1021/jf504383g
- ↑ Günata, Ziya; Wirth, Jérémie L.; Guo, Wenfei; Baumes, Raymond L. (2001). "Carotenoid-Derived Aroma Compounds". ACS Symposium Series. 802: 255. doi:10.1021/bk-2002-0802.ch018. ISBN 0-8412-3729-8.
|chapter=ignored (help) - ↑ P. Winterhalter, M. A. Sefton and P. J. Williams (1990). "Volatile C13-Norisoprenoid Compounds in Riesling Wine Are Generated From Multiple Precursors". Am. J. Enol. Vitic. 41 (4): 277–283.
- ↑ Zelena, Kateryna; Hardebusch, Björn; Hülsdau, BäRbel; Berger, Ralf G.; Zorn, Holger (2009). "Generation of Norisoprenoid Flavors from Carotenoids by Fungal Peroxidases". Journal of Agricultural and Food Chemistry. 57 (21): 9951–5. doi:10.1021/jf901438m. PMID 19817422.
- ↑ Cabaroglu, Turgut; Selli, Serkan; Canbas, Ahmet; Lepoutre, Jean-Paul; Günata, Ziya (2003). "Wine flavor enhancement through the use of exogenous fungal glycosidases". Enzyme and Microbial Technology. 33 (5): 581. doi:10.1016/S0141-0229(03)00179-0.
- ↑ Vivas N, Vivas de Gaulejac N, Nonier M.F and Nedjma M (2001). "Incidence de la gomme arabique sur l'astringence des vins et leurs stabilites colloidales" [Effect of gum arabic on wine astringency and colloidal stability]. Progres Agricole et Viticole (in French). 118 (8): 175–176.
- ↑ Lamont, Kim T.; Somers, Sarin; Lacerda, Lydia; Opie, Lionel H.; Lecour, Sandrine (2011). "Is red wine a SAFE sip away from cardioprotection? Mechanisms involved in resveratrol- and melatonin-induced cardioprotection". Journal of Pineal Research. 50 (4): 374–80. doi:10.1111/j.1600-079X.2010.00853.x. PMID 21342247.
- ↑ M. Baldy "The University Wine Course" Third Edition pgs 37-39, 69-80, 134-140 The Wine Appreciation Guild 2009 ISBN 0-932664-69-5
- ↑ Brettanomyces Monitoring by Analysis of 4-ethylphenol and 4-ethylguaiacol at etslabs.com
References
- Comprehensive Natural Products II — Chemistry and Biology, chapter 3.26 – Chemistry of Wine, volume 3, pages 1119–1172. Véronique Cheynier, Rémi Schneider, Jean-Michel Salmon and Hélène Fulcrand, doi:10.1016/B978-008045382-8.00088-5
External links
- Wine Chemistry and Biochemistry. by M. Victoria Moreno-Arribas,Carmen Polo and María Carmen Polo, on Google books
- Mass Spectrometry in Grape and Wine Chemistry. by Riccardo Flamini and Pietro Traldi, on Google books