Thread: Why did my garlic turn blue?

Hi folks.

we often use garlic in our kitchen, and the standard procedure is to crush it with salt on a breadboard, using the convex side of a fork as a pestle.

I thought this kind of physical labour should have no place in the 21st century, and so one day I put a lot of garlic with salt into a blender, then stored the resulting pulp in the freezer.

This saved us a lot of time (and bent forks), and worked beautifully for lots of recipes, until one day my wife wanted to fry some chicken.

Put in the hot frying pan with (refined rapeseed) oil, not on the meat but next to it, the garlic-and-salt pulp turned a pale but distinct blue. This never happens with garlic crushed with salt the traditional way.

What happened? Is it because the blender ground the garlic more thoroughly than the fork would? Or is it because the pulp had been frozen?

Is the funny bluish stuff OK to eat?

TIA for any enlightment.

According to an article* it turns blue because the garlic contains sulfur compounds which can react with various substances.

An abstract from the cited article there summarized:
The discoloration is due to pigments that form between sulfur compounds in garlic and amino acids. When the garlic tissue is disrupted, as happens in processing, an enzyme is liberated and reacts with it to form thiosulfinates compounds that then react with the natural amino acids in the garlic to form blue pigments. The age of garlic determines how much isoalliin there is in the first place, and the nature of the processing determines how much enzyme is liberated.

http://whatscookingamerica.net/Q-A/bluegarlic.htm

EDIT:
Sorry, didn't read your post throughly so I cannot explain why it happens in one situation but not in another

Thanks a lot Dararck The article explained everything.

To begin with, it says the bluish garlic is still safe to eat.

Then, it says that the reactions that yield the funny colors depend on disruption of garlic tissue - so, just as I thought, the blender disrupting it more heavily leads to more of the color being produced.

My blended garlic also spent more time with the salt, and went through more temperature change (deep freezer) than the fork-crushed stuff did. Both factors are important contributors to the, erm, bluification.

Cheers - Leszek.