Why Does Garlic Turn Green?


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Garlic is a critical component in numerous kitchens. It’s typical for several individuals to buy in large quantities to avoid running out. However, in these bulk purchases, encountering garlic bulbs with green sprouts, bulbs with slightly tinged green cloves, or garlic cloves that change color to blue or green once cut is not unusual. Is this indicative of the garlic being rotten? Here’s some crucial information about garlic that turns green.

What Is Garlic?

Garlic is a root vegetable for both culinary and medicinal purposes, related to leeks, shallots, and onions. The organosulfur compounds found in garlic are responsible for its bold flavor and health benefits. Besides bolstering your food’s flavor, garlic also supplies essential nutrients that support your general well-being, including selenium, calcium, vitamin c, and vitamin B6. Garlic also helps reduce your need for less healthy flavor enhancers like salt.

That said, eating stale garlic can cause food poisoning. So is it safe to eat garlic that’s turning green, and what causes garlic to turn green or blue in the first place? This article will expand on what causes garlic to turn green and whether green garlic is safe for consumption.

Why Does Garlic Turn Green?

Natural Aging

The sprout at the center of a garlic clove is called a germ. The germ is small, pale, and tender when the garlic is young. As the garlic ages, the germ starts to turn green, grows larger, and develops a bitter taste. We highly recommend removing the germ if your garlic starts turning green and you want to use it raw or quickly cooked. While the green part is not toxic and is safe to eat, you may want to remove it as it imparts a bitter flavor. To remove the green part of the garlic;

  • Cut the clove in half
  • Use a paring knife to pry the germ out

If you are slow-cooking the garlic in a braise soup or stew or if you are baking it whole, there is no need to remove the germ as more prolonged cooking tends to tame the bitterness.

Harmless Chlorophyll

Since garlic is a vegetable, it naturally produces chlorophyll. Therefore, if your garlic starts turning green on the outer part of the clove, the chances are high that it was exposed to a lot of sun. Another reason is that it may have been exposed to a significant influx of fertilizer. These two features cause it to produce chlorophyll and turn green. That said, chlorophyll is entirely harmless.

Chemical Reactions

Sometimes, a perfectly colored clove of garlic can start to turn blue-green when you pan-fry the crushed garlic cloves. While green or blue pigment that forms may seem like a reason for alarm, your garlic is still perfectly safe to eat. Generally, what happens is that this color is most likely the result of a reaction between the sulfur compounds and common amino acids (building blocks of protein) that are naturally present in garlic.

These compounds start safely locked within individual cells in garlic cloves and are released once you cut or grate them. When you cut or grate garlic, it removes these compounds and exposes them to each other. These compounds start reacting with each other with the help of enzymes, causing your garlic to turn green. This same reaction occurs with pickled garlic. Pickled garlic with blue color is entirely safe to eat. So why do some garlic turn green and others not?

Well, this all comes down to the age of the garlic. Older garlic tends to build up larger quantities of compounds than fresher or younger garlic. The more the number of chemical precursors in your garlic, the more likely it is to form these green or blue compounds. Also, the sulfur compounds in garlic may react with copper found in water supplies to form copper sulfate- a blueish or blue-green compound.

Since the color compounds are created from the same chemical reaction as the aromatic compounds, it goes without saying that garlic that turns green after cutting will have a more robust flavor than garlic that stays creamy white.

Don’t Want Green or Blue Garlic?

If you do not want your garlic to turn green or have a strong flavor, there are several ways you can prevent this:

Work Fast and Avoid High Temperatures When Preparing Your Garlic

Chemical reactions start occurring the moment you cut your garlic. High temperatures speed up these reactions. Ideally, it would be best if you kept your garlic in the fridge to minimize the reaction.

Cook Your Raw Onions and Garlic Separately

Onions and garlic contain many of the same precursors. When you chop or grate them together, you essentially provide the garlic with extra building blocks to create the green pigment. It is a good idea to cook the onions first to denature their precursors before adding your garlic.

Use Distilled Water for Pickling

The copper traces found in tap water can make your garlic turn blue. Distilled water does not have the trace metals found in a lot of tap water that gives your garlic that blue-green color.

Can You Eat Blue or Green Garlic?

Garlic that turns blue or green is perfectly safe to eat. The presence of color does not affect the garlic’s flavor.

In Conclusion

It is safe to say that the green or blue color that occurs in garlic is generally a result of age and is perfectly normal. While it is safe to consume colored garlic, we recommend you always go for fresh garlic whenever possible. Why? Fresh garlic tastes better. The flavor is nice and robust, and the garlic smell is breathtaking.