Most meringue recipes call for a pinch of cream of tartar. What the hell is the stuff and what does it do? Cream of tartar is another name for the acid potassium bitartrate and it’s a byproduct of winemaking. Who knew? The acid crystallizes in wine casks during fermentation. The process for extracting the crystals from wine dates back to ninth century persia, but traces of the acid have been used to date the winemaking process back about 7000 years. Despite it’s auspicious history, cream of tartar wasn’t commercially available until the 1800s.
I had always assumed that cream of tartar was some horrible, industrial chemical byproduct and I’ve only got my high school history teacher to blame! He made us read Herman Melville’s sendup of the industrial revolution, The Tartarus of the Maids:
“Then, shooting through the pass, all alone with inscrutable nature, I exlaimed–Oh! Paradise of Bachelors! and oh! Tartarus of Maids!”
The story is about a visit to a hell-like paper mill and the ghostlike women whose lives are drained by their industrial labor. It’s a great (but depressing) story…that has nothing to do with cream of tartar. Word association is a powerful thing.
But what does it actually do?
Cream of tartar is most often used in baking as either a stabilizer or a leavening agent.
Remember learning about acids and bases back in the 7th grade? Well, egg whites have a pH of about 9, which makes them a base. Cream of tartar is about a 3 so just a little bit edges the egg whites towards the acid side of things. The acidity helps the coiled strands of protein (egg whites) relax and unwind. Think of it as unraveling a sweater! The long strands stay whipped up.
You could use other acids to achieve the same result, but most edible acids (like vinegar or lemon juice) have strong flavors. Nobody wants their meringue to taste like vinegar. Cream of tartar doesn’t taste like anything. It’s more expensive than vinegar, but one jar of the stuff can make about a hundred pies so you’ll be fine.
Cream of tartar’s acidity also makes it a great leavening agent, but that’s a story for another day. For now, try using it to clean your aluminum pans or remove hard water stains.
I learned a lot of the information above from Paula Figoni’s How Baking Works. It’s a great resource for studying the science behind baking and an indispensable resource for anybody developing their own recipes.