Why is my garlic blue and is it safe to eat?

December 21, 2023

Cooking or using garlic with vinegar or an acid will often turn it blue or green in color. Why does it happen? Is it normal? Is it still safe to eat?

Maybe you've encountered it while cooking in the kitchen yourself, or perhaps you've seen it happen in a dish or even one of our pickle jars— blue garlic.

It can be a bit of a... er... "jarring" sight at first. Your garlic has changed color. "Blue garlic" can actually appear in a variety of hues, from bright green to turquoise, to aquamarine to pure blue.


So, let's answer some quick and immediate questions:

Is it mold? No.

Is it safe to eat? Absolutely, yes.

Is the taste different? Nope. Still delicious garlic.

Is it normal? Yes, it's just the result of a natural reaction caused by certain environmental conditions.

So let's get into it...


Why does garlic turn blue or green?

Garlic may change color to a shade of blue or green when combined with acids, particularly after being stored in cold environments.

The color change happens when the enzymes and amino acids in the garlic, which contain sulfur, are introduced to an acid. In our case, the acid is pickle brine, which contains vinegar.

The enzymes in the garlic (which are the same ones responsible for garlic's flavor) become activated by the acid, and create a compound called isoalliin. This is the compound responsible for producing blue or green pigments in the garlic.

Isoalliin typically forms when storing garlic in cool pantries or cold fridges, and commonly occurs more often during winter, but it can also happen during cooking as a reaction with the metals and materials in different pots and pans.

While it may be visually alarming at first, it is perfectly safe to eat and tastes exactly the same.

And if you ask us, it's actually a pretty cool reaction when you see it.


Want to learn more about the science behind blue garlic?

Read Harold McGee's New York Times article, When Science Sniffs around the Kitchen