Interesting...

[Flame]

I put a pork roast in the crock pot earlier today...salted, peppered it, added some red wine vinegar to the bottom of the crock for tenderization.  Smashed a few garlic gloves and put them on top of the roast.

Just wandered into the kitchen, and the garlic has turned blue.

Any ideas why??

[bijou]

Garlic contains sulfur compounds which can react with copper to form copper sulfate, a blue or blue-green compound. The amount of copper needed for this reaction is very small and is frequently found in normal water supplies.

Garlic Can Turn Blue
Raw garlic contains an enzyme that if not inactivated by heating reacts with sulfur (in the garlic) and copper (from water or utensils) to form blue copper sulfate. The garlic is still safe to eat.

Garlic can turn Green
If the garlic was not fully mature or dry, pigments in the garlic may turn green when in the presence of acid. Garlic will also turn green (develop chlorophyll) if exposed to an temperature change or is exposed to sunlight. Some people say it can be stored for 32 days at or above 70 - 80° F to prevent greening, but I'm not yet sure that is true. Green garlic is safe to eat.

http://www.gourmetgarlicgardens.com/pickle.htm

I think that in a slow cooker it takes so long to heat up the garlic that it has time to react, whereas with ordinary cooking it will get hot quickly enough not to turn blue.  Just my guess, I'd never heard of this before.

[Flame]

Thanks for the info, Bijou.  It was quite a surprise when I went into the kitchen!

[bijou]

Thanks for the info, Bijou.  It was quite a surprise when I went into the kitchen!

If you were having a Halloween party it would be a great addition to a spooky pizza.

[debk]

It's absorbed the red wine vinegar, which is sort of purplish.

[Flame]

It's absorbed the red wine vinegar, which is sort of purplish.

no...it's not purplish, it's BLUE...like a greeny-blue...

[debk]

It's absorbed the red wine vinegar, which is sort of purplish.

no...it's not purplish, it's BLUE...like a greeny-blue...

Chemical reaction of the vinegar with the garlic? 

Do you have any minced garlic in a jar....the kind that's in olive oil?

If you do, take a little bit and drop it into the liquid and see if it changes color...if it does, you will know that's what it is. If it doesn't, I don't know. Fresh garlic doesn't change color after being cut. It's like onions.