Q&A: Is it safe to bake with spoiled milk?

Does baking with spoiled milk, which my mother does routinely, pose any health risks? —Z.C., Grand Junction, Colo.

Probably not—but that doesn’t mean it’s a good idea. Nearly all milk sold in grocery stores today is pasteurized, primarily to prevent tuberculosis and brucellosis. That greatly diminishes the chance that you could pick up other serious illnesses from the milk, even if it’s old. However, pasteurization sometimes does not kill all spoilage bacteria. So as milk ages, it harbors increasing amounts of other, less virulent bacteria that might cause nausea, stomach cramps, or diarrhea, particularly if it’s left unrefrigerated. While the heat of baking destroys many of those bugs, experts say it’s probably not worth the risk. And excessively spoiled milk may give an off flavor to your baked goods. Instead, use buttermilk, or stir vinegar or lemon juice into fresh milk (1 tablespoon per cup) to simulate the curdling and acidity.

Take a look at the sure signs of food poisoning, and see our tips on protecting yourself and your family.