[ANSWERED] Why Did Garlic Turn Green in Slow Cooker?

While cooking garlic with something on a slow cooker, you might notice that your garlic is turned emerald green. As aren’t familiar with the green color of garlic, it is normal to get shocked to see it. Again, the bluish-green color of the garlic may make them look spoiled or poisonous.

For this, you might think why your garlic turned green or if the slow cooker has something to it or not. Well, first of all, let me assure you that your slow cooker probably isn’t the culprit for this issue. It is a harmless enzyme reaction that occurred with other acidic elements in the slow cooker.

In this article, we will discuss the reasons that may have turned your garlic green while cooking it in a slow cooker, whether it is edible or not, and much more regarding this topic. So, continue reading to learn more about this strange phenomenon.

why did garlic turn green in slow cooker

Why Does Garlics Turn Green in a Slow Cooker?

While cooking garlic in a slow cooker, your garlic may turn green. Although it isn’t frequent, it is a completely normal case. It happens due to some harmless chemical reaction with the elements of garlic and other enzymes. Here are the possible reasons why your garlic may turn green in the slow cooker:

1. Enzymatic Reaction

Garlic contains an enzyme called “Alliinase” which can break down by reacting with acetic acid, lemon juice, amino acid, or other acidic elements while cooking it with other foods.

The alliinase then breaks down the amino acid-alliin into “allicin” which is also known as “Diallyl-thiosulfinate”. As garlic also contains some protein, the allicin affects the protein molecules and turns them blue-green. As a result, the garlic looks green. However, it doesn’t affect the taste or nutrients of garlic.

2. Nonenzymatic Reaction

Garlic also contains sulfurous compounds and when garlic is crushed, the “alliin” reacts with the sulfur and makes a compound named ” S-Allyl-L-Cysteine Sulfoxide”. It creates the unique smell of garlic.

When it comes in touch with acetic acid, it creates “Allicin” which reacts again with the monocarboxylic acid (Vinegar contains acetic acid and monocarboxylic acid). As a result, it forms a carbon-nitrogen ring called “Pyrroles”. This pyrrole makes the garlic look green.

3. Chemical Reaction

As we already have mentioned that garlic contains sulfur compounds, which can react with the copper of the slow cooker stoneware to form copper-sulfate while cooking. You may already know that copper sulfate is known as blue vitriol. Thus, it can make the garlic look blue. However, it is still safe to eat.

It can also react with the iron or aluminum ion of the stoneware by slow cooking the garlic for a long. As a result, the garlic might look bluish-green or green.

What to Do if Garlic Turns Green?

If your garlic turns green, there is nothing to be worried about as they are completely safe to eat. It is just like the term that sulfur is poisonous but sulfur contained in garlic is healthy. It doesn’t matter what reaction happened in the slow cooker or what compound the garlic has made, you can eat them without any hesitation.

In fact, the demand for green garlic is higher than for normal garlic. Pickled garlic called “Laba” in China is prized for its green and blue color. In that pickle, they do not add any chemical or food color to make the garlic green. They simply cut both ends of the garlic to get access to the enzyme and dump them under a solution that is made of vinegar and sugar.

So, if your garlic turns green, be happy and eat them without being worried. But as they may spoil the look of your recipe, there is something that you can do to prevent them from turning green.

Tips to Prevent Garlic from Turning Green

Here are some effective tips that you can apply to prevent your garlic from turning green while cooking it in a slow cooker:

  • Do not add acetic acid at the beginning. Wait until the garlic is fried or cooked completely before adding vinegar or lemon juice to your recipe.
  • Do not leave the garlic for a long time before cooking after cutting them.
  • Cook at a high temperature. Cooking garlic at low temperatures can activate enzymes that make them green.

FAQs – Frequently Asked Questions and Answers 

Why Did My Garlic Turn Blue in Slow Cooker?

The reason for garlic to turn blue is the same as the reason for garlic to turn green. The reaction between enzymes and sulfur-containing amino acids in the garlic creates a blue pigment that makes garlic look blue.

Can You Eat Garlic That Has Turned Green?

Yes, garlic that is turned green while cooking or pickling process is completely safe to eat. The color doesn’t affect the taste and nutrients of garlic. However, if garlic turns green because of a mold attack or due to storing it in a damp place for a long time, then it isn’t safe to eat.

Why Did My Garlic Turn Green Overnight?

Garlic usually doesn’t turn green overnight unless it is affected by mold or types of penicillin. However, during the pickling process, the garlic is dumped under the vinegar which will surely turn the garlic green overnight. In this case, it is completely normal and safe to eat.


Garlic doesn’t turn green normally while cooking unless the enzyme and chemicals of the garlic react with the other acetic food elements. The reaction mainly begins at low heat and thus, you may notice this frequently with a slow cooker. However, it is completely safe and healthy to eat garlic that turned green during cooking in a slow cooker. That’s all for today, we hope, this article has proven helpful in reducing your anxiety about your garlic that turned green while cooking in a slow cooker. Thanks for reading.

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