Tartaric acid
Also written L-tartaric acid
Quick answer
The acid of tamarind: it builds up in the ripening pod, is the main source of the pulp’s sourness, and stays there while the sugar rises around it.
What it does
Tartaric acid is what makes tamarind sour. Following the metabolites of the fruit through its development, a genome study found that tartaric acid accumulates at high levels and is the major contributor to the sour flavour. The handbook says the same and adds what makes tamarind unusual: the acid does not disappear as the fruit ripens but is matched, more or less, by increasing sugar, so that tamarind is said to be at once the most acid and the most sweet of fruits.
How it behaves when cooked
Four properties of the molecule, and what they mean at the stove.
- Volatility
- low
- Fat solubility
- low
- Water solubility
- high
- Heat stability
- high
Tartaric acid dissolves very freely in water, by the reference figure about 1.4 kg in a litre at 20 °C, and has a strong computed preference for water over fat. So the acid goes wherever the water in a dish goes, and the handbook’s uses for the sour types are all watery ones: juice, syrup, jam, and green fruit to sour soups of fish and meat. Because the acid stays in the fruit as it ripens while the sugar climbs, how sour a tamarind tastes is a matter of the balance between the two and not of the acid alone, which is why the ripe fruit of the sweet types can be eaten as it is. That it is not volatile and survives cooking is the ordinary behaviour of a solid fruit acid; it was not measured in anything read for this profile.
Spices that carry it
Recorded on the compound rather than on each spice, so the two cannot disagree.
- TamarindPrincipal component
The acid that accumulates in the pod and the main contributor to its sourness; ripening adds sugar without taking the acid away.
- VerjuiceMajor component
The leading acid of the juice of unripe grapes: one bottled Iranian verjuice held 1,282 mg per 100 g, six times any other acid measured in it, and a Lebanese study reckons the acidity of its juices as tartaric acid.
- SumacContributing component
Named in the sumac profile among the further organic acids that add to its acidity; no measurement of it in sumac was read for this profile.
Not to be confused with
Compounds a reader is likely to take for this one, and why they differ.
Citric acid
The acid of citrus, and of most of the dried souring spices. Tamarind’s sourness is tartaric, a different acid, and it arrives with a large amount of sugar, which is why lemon juice sours a dish without standing in for tamarind.