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Ask the Inquisitive Cooks

April 29, 2003

This week's question:
“Why does leftover coleslaw turn bitter?”


Why does leftover coleslaw turn bitter?
—From Patty

Check back next week for a new kitchen science Q&A, and also check out the monthly feature article by the Inquisitive Cooks.

(Meet the Inquisitive Cooks)




Dear Patty,
Cabbage, the foundation of the salad called coleslaw, is an interesting vegetable. It's a member of the Cruciferae clan, more commonly known as the mustard family. All its members bear sulfur-containing compounds, which are volatile by-products of mustard oil.


When cabbage is left undisturbed in the garden, its mustard oils, which are attached to sugar molecules, simply remain unnoticed. But when garden pests nibble cabbage leaves, these oils are indeed put to use. When plant cells are broken, the oils are separated from the sugar molecules by an enzyme and released as a very bitter compound. It's a clever defense mechanism for the cabbage plant to discourage hungry foragers.

Of course, slivering or dicing cabbage to make coleslaw also ruptures plant cell walls, so the same reaction is triggered. At first, any bitterness may seem pleasantly tangy as the salad's dressing mellows cabbage flavors. After a while, however, the released mustard oils definitely become more noticeable and pungent.

Coleslaw is appealing in both its crunch and tang. It's at its best, however, when made shortly before it's eaten. So try to use only the amount you think will get eaten.

Good wishes,
Anne and Sue


Anne Gardiner & Sue Wilson are the authors, with the Exploratorium, of the book The Inquisitive Cook.




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