Ever seen a green raw onion? Learn about the harmless chemical reaction that causes this color change and why it's still perfectly safe to eat.
1 Answer
Raw onions can turn green in the fridge due to the presence of sulfur compounds that react with amino acids, creating sulfoxides which, when exposed to light, can cause a green tint. This is a natural reaction and the onion is still safe to eat.
Detailed Explanation:
The green color you sometimes see on raw onions, especially when they've been cut and stored in the refrigerator, is a result of chemical reactions involving sulfur compounds naturally present in the onion. Onions contain amino acids and sulfur compounds. When an onion is cut, these compounds are released and can react with each other. These reactions can produce sulfoxides.
These sulfoxides, when exposed to light (even the relatively low light levels inside a refrigerator), can undergo further reactions that result in the formation of a bluish-green pigment. The intensity of the green color can vary depending on the onion variety, storage conditions, and the amount of light exposure. It's important to note that this color change doesn't indicate spoilage or make the onion unsafe to eat. The green color is simply a visual indicator of these natural chemical reactions.
Pro Tip:
To minimize greening, store cut onions in an airtight container in a dark place in the refrigerator. This reduces light exposure and slows down the chemical reactions that cause the color change.