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| Properties | |
| C4H4O62− | |
| Molar mass | 148.07 g/mol |
| Conjugate acid | Bitartrate |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Atartrate is asalt orester of theorganic compoundtartaric acid, adicarboxylic acid. The formula of the tartratedianion is O−OC-CH(OH)-CH(OH)-COO− or C4H4O62−.[1]
The main forms of tartrates used commercially are pure crystalline tartaric acid used as anacidulant in non-alcoholic drinks and foods,cream of tartar used in baking, andRochelle salt, commonly used in electroplating solutions.
Asfood additives, tartrates are used asantioxidants, acidity regulators, and emulsifiers. Examples include
Inwine, tartrates are the harmless crystalline deposits that separate from wines duringfermentation and aging. The principal component of this deposit ispotassium bitartrate, a potassium salt of tartaric acid. Small amounts of pulp debris, dead yeast, and precipitated phenolic materials such astannins make up the impurities contaminating the potassium acid tartrate.
The wine industry is the only source of commercial tartrates, and the crystalline encrustations left inside fermentation vessels are regularly scraped off and purified for commercial use.
Tartrates separate from new wines because they are less soluble in alcohol than in non-alcoholic grape juice. The exact figures vary according to variety and region, but approximately half of the tartrate soluble in grape juice is insoluble in wine. The problem is that the tartrate may remain in a supersaturated state after bottling, only to crystallize at some unpredictable later time.
Tartrates precipitated in red wine usually take on some red pigment and are commonly dismissed as mere sediment; in white wines they can look alarmingly like shards of glass. The modern wine industry has decided that tartratestabilization is preferable to consumer education.[2]
Tartrate is also used as a retarder to delay the setting time ofconcrete when temperature is too high.
