Why Does Garlic Turn Blue When Pickled?

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The garlic in my chive brine turned green

A while back I lactic-fermented some garlic chives and radish, and there was garlic in both brines. Only the garlic in the chive brine turned green. The radish one stayed normal. I ended up making dumplings just so I could use up a few of those cloves, and yes I ate them, they were fine.

My garlic paste went green with no acid at all

Then at a barbecue dinner with friends I made fresh garlic paste, cooked the minced garlic in a small saucepan with oil, added a spoon of salt and sugar. It was the normal colour at first and smelled great. I left it for an hour, went to grab it, and it had turned green. I read that garlic goes green in acidic conditions, but I didn't add anything acidic, so I still don't really know what happened there. The next day I made another batch with garlic, hot oil and a few green Sichuan peppercorns, and that one went green too. I'd never seen it before, my garlic paste has always been the same colour as the one you get at hotpot restaurants.

Then my Laba garlic went blue

Laba garlic is garlic pickled in vinegar, and it's supposed to go green. Mine was fine for the first couple of days, then on day 3 it turned blue, and not even green, properly blue. I stood there looking at it for a while.

So why does garlic turn green or blue?

From what I read, when garlic is in an acidic environment the cell structure breaks down and an enzyme called alliinase gets activated, and that reacts with alliin to make allicin and other sulfur compounds. Those sulfur compounds then go on to form pigments, which is what turns the cloves green or blue-green.

Garlic chives and garlic are both in the allium family and both full of sulfur compounds, so I think the chive brine just had more of that material to work with, which would explain why only that jar changed. Fresh garlic also has more active enzyme, so it turns more easily, and chopping or smashing it helps too since the enzyme and alliin come into contact faster.

Is green or blue garlic safe to eat?

That was my first worry, because I'd already eaten some of the garlic at lunch before I noticed anything. I looked it up straight away and everything said the colour change is a normal reaction and the garlic is still fine to eat. I asked an AI app as well and got the same answer. It still looks strange the first time, but it's just chemistry, nothing has gone bad.

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