Why are tarts and pastries made in bakeries so much smoother than when we make them at home? That's because they use a secret ingredient - cream of tartar.
Uses in the kitchen
Chemists have another name for cream of tartar - they call it potassium hydrogen tartarate. It is a white, sour-tasting crystalline powder, and has many uses in the kitchen.
When you beat egg white, it produces foam that traps air. This is what helps make pastry light and fluffy. But the foam can break up, so bakers add a pinch of cream of tartar. This prevents the foam from collapsing. This helps the pastry remain smooth throughout.
Cream of tartar has many other uses too. If you make sugar syrup (for use with gulab jamuns, rasgullas etc), add a pinch of cream of tartar. That will prevent the sugar from crystallizing out of the syrup. Mixed with potassium chloride, it can serve as a substitute for salt. This is useful for people who have high blood pressure and should not take sodium.
If you add a pinch while boiling vegetables, it helps them keep their colour. This is because vegetable pigments are very sensitive to changes in pH. Cream of tartar acts a buffering agent, i.e. it prevents the pH from changing.
What do you do if you run out of baking powder, and the shops are closed? You can make your own with baking soda and cream of tartar. When baking a cake, you can add a pinch each of these powders and mix well. The two chemicals react to form carbon dioxide in the oven, which causes the dough to rise. Baking soda alone will not work, as it needs an acid to activate it.
Cream of tartar is also a good rust remover. To use it, mix it with hydrogen peroxide and apply it on metallic objects. You can mix it with vinegar and use that mix to clean copper or brass utensils.
Isn't it a good chemical to have around the house?