The Exploratorium is more than a museum. Explore our online resources for learning at home.

The Accidental Scientist: Science of Cooking
Candy Bread Eggs Pickles Meat Seasoning
Ask the Inquisitive Cooks    

"Why do recipes recommend a pinch of cream of tartar and a dash of vinegar in toffee?"

Dear Anne and Sue,

Why do recipes recommend a pinch of cream of tartar and a dash of vinegar in toffee? What does this do?
— S. O'Brien


Still have more questions? You'll find more answers in our archived monthly feature articles by the Inquisitive Cooks.

(Meet the Inquisitive Cooks)

Cream of tartar, vinegar, and brown sugar are all commonly used in toffees. Each of these ingredients is acidic, and with reference to candy-making, each is referred to as an interfering substance, a term that aptly describes its function in a boiling syrup.

In a candy syrup, the sucrose molecules of sugar react with water in the presence of an acid to form an invert sugar. This means that as boiling continues, a portion of the sugar separates into its constituent parts—glucose and fructose. Adding cream of tartar and a dash of vinegar to a toffee recipe helps bring about this change. The presence of invert sugar is important because it influences the amount of crystal formation as well as the size of the crystals that form as candy hardens.

The bottom line on this one is that the proportion of interfering substances in the syrup has a strong influence on the texture of the finished toffee. Candy-making is tricky, however, because lots of other factors come into play. Do check out the candy section for more information.

We suspect that at this time of year your question will be of interest to other people too. Thanks for asking it!

Anne and Sue


- - - Science of Cooking - - - Webcasts - - - Ask The Inquisitive Cooks - - - Share & Discuss - - -


© Exploratorium | Use Policy | Privacy Policy