Wine chemistry

Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 4.

Gum arabic has been used in the past as fining agent.

List of additives permitted for use in the production of wine under EU law:

potassium alginate
potassium caseinate
casein
isinglass
silicon dioxide
edible gelatine
acacia (gum arabic)
milk/lactalbumin
proteins of plant origin
ovalbumin (egg white)
alumino silicates
ferrous sulfate

activated charcoal

neutral potassium tartrate
potassium bicarbonate
calcium carbonate

metatartaric acid
water

rectified concentrated grape must
saccharose
tannin
oxygen

pectolytics
urease

ammonium bisulphite
thiamine hydrochloride
yeast cell walls
yeasts for wine production
diammonium phosphate
ammonium sulphate
ammonium sulphite

potassium ferrocyanide
calcium phytate
citric acid

potassium bitartrate
yeast mannoproteins
Preservatives sorbic acid
sulphur dioxide
argon
nitrogen
potassium bisulphite
dimethyl dicarbonate (DMDC)
carbon dioxide
potassium metabisulphite/disulfite
allyl isothiocyanate
lysozyme
potassium sorbate
ascorbic acid

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.

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. 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.

...
Wikipedia