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Dec 21, 2007 08:44 AM

Onion & garlic turn green when sautéed!?

While cooking a massive batch of black bean burritos bound for the freezer , I was sautéing garlic (20 cloves, crushed) and onions (4 large, minced) in olive oil in a Calphalon pan.
While cooking, this 3-ingredient-mixture turned a bright green colour. Has anyone else experienced this phenomenon?

The only thing I can think of is that I had over processed the garlic and onion in the food processor resulting in a mashed potato consistency.

thanks. Kurt

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  1. If you pureed the mixture, that releases some sort of enzymes that makes the onions and garlic turn green when heated. In indian cooking, we often puree onions and then cook them until brown, and they stay green for several minutes until the browning begins.

    1 Reply
    1. Acidity releases sulfur naturally occurring in the garlic which combines with trace copper either from your pan or from your water or already present in the garlic, which forms copper sulfate a greenish blue compound. It is considered harmless in trace amounts involved in cooking. I have heard that this only happens with fresh picked garlic or bottled fresh refrigerated garlic. Fresh garlic aged a week or two is less likely to turn green.