Why Does Garlic Turn Blue?

Garlic cloves are generally creamy white or yellow in color, but sometimes during the preparation of a meal that creamy white garlic can turn an unappetizing color of blue (or even green) — and it's definitely a bit unsettling. But is there any cause for concern? Why does garlic really turn blue, and are you even supposed to eat it after it dons its new shade?

Blue or green garlic is completely safe to eat, according to food safety specialist Angela M. Fraser, Ph.D. (via Food Safety Education). Garlic contains sulfur compounds (that help give it that distinct, garlicky taste) that can react with copper. This copper can be found in perfectly innocuous places, such as tap water, or in other ingredients in your meal, such as butter or lemon juice — and it only takes a very small amount of copper to produce a reaction. When the sulfur compounds interact with copper, it turns into copper sulfate, which can turn your garlic bits blue or green (think old pennies or the Statue of Liberty). It doesn't mean that blue or green garlic is toxic, though.

This color-changing garlic phenomenon isn't limited to cooking garlic, either — the folks at Epicurious noted their jars of pickled garlic were slowly turning blue.

If the idea of blue garlic turns your stomach, there are a few ways to avoid it. It turns out that if you use fresh garlic rather than older garlic, it's less likely to change colors (via Serious Eats). It's also better to avoid cooking garlic together with onions, as the onions can impact the potential of the reaction taking place because there will be more sulfur compounds to go around. Cooking garlic at a hot temperature can help, too, as simmering at low temperatures increases the likelihood that it will turn colors. Finally, if your recipe calls for acidic ingredients, allow your garlic to cook a bit to break down its enzymes before adding any acid. But even if your garlic does turning a shocking shade of blue next time you're making dinner, you now know you can chow down without hesitation.