In chemical terms, it is potassium hydrogen tartrate which is basically partially neutralized tartaric acid.聽Pasteur became interested in the chemistry of winemaking and launched into a study of tartaric acid and its various salts.聽He found that sodium ammonium tartrate which he prepared from natural tartaric acid was not exactly the same as the version made from tartaric acid that had been synthesized in the laboratory.
When he examined the latter through a microscope, he found that it was composed of two kinds of crystals which were mirror images of each other.聽He laboriously separated these with tweezers and discovered that one set of crystals was identical to the tartrate prepared from the 鈥渘atural鈥� source.聽He then went on to suggest that the mirror image crystals were likely made of mirror image molecules and that nature produced only one of these two versions.聽A brilliant deduction!聽 Eventually van鈥檛 Hoff and Lebel concluded that this was possible only if the molecules were not planar but three-dimensional.聽And thus was born the idea of the tetrahedral carbon atom.
Emotional connections aside, there are still plenty of reasons to appreciate cream of tartar.聽It is a cheap, safe, readily available mild acid.聽 It is ideal for the generation of carbon dioxide from baking soda.聽In fact, one version of baking powder is a mixture of sodium bicarbonate and cream of tartar.聽When the mixture dissolves, bubbles of carbon dioxide are released.聽The same chemistry can be used to keep drains clear.聽Just make up a mix of one cup bicarbonate, one quarter cup cream of tartar and one cup of salt (for increased density) and periodically pour a few spoonfuls down the drain.聽The bubbling action can dislodge small blockages.
Candy makers also know all about cream of tartar.聽Candies are basically made by cooling down solutions in which a lot of sugar has been dissolved. But this has to be done in a fashion that ensures small crystal formation otherwise the candy becomes too brittle and crunchy.聽If a small amount of cream of tartar is added, some of the sucrose is hydrolyzed to glucose and fructose which are less likely to form large crystals.
There is something else that cream of tartar can interfere with.聽Protein molecules joining to each other.聽That鈥檚 just what happens when we whip egg whites to make meringue.聽Coiled proteins unwind and link up in a rigid three-dimensional network.聽Sometimes, however, the proteins form too many links to each other and over-coagulation results.聽This causes the meringue to be lumpy.聽The addition of cream of tartar limits the extent to which proteins can bond to each other.聽So it is a pastry chef鈥檚 beloved friend.
If that still isn鈥檛 enough to make you appreciate cream of tartar, how about its cleaning abilities?聽A blackened aluminum pot will shine like new if you boil water with two spoonfuls of cream of tartar per litre in it.聽Finally, cream of tartar complexes iron so it will even take rust stains out of fabrics and the bathtub.聽Obviously no household should be without it.
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