Why Does Garlic Turn Blue and Is Blue Garlic Safe To Eat?

Studies prompted by the food industry as a result of increasingly occurring batches of accidentally colored garlic have begun to unlock the mystery of why garlic turns blue.These studies have found a number of complicated chemical processes responsible for garlic turning shades of blue, green, and even pink under certain conditions.

The colors occur when enzymes and amino acids present in garlic react with the sulfur compounds responsible for garlic’s pungent smell. The reaction causes different multipyrrole molecules to form. Different types of multipyrrole molecules are responsible for the different pigments. The multipyrrole molecule most familiar to us is chlorophyll, produced by plants in the presence of light; however, chlorophyll is not produced by the cooking or pickling processes that turn garlic blue.

Variables Involved in Garlic Turning Blue Here are some of the factors that have an influence on garlic changing color:

• Age of the garlic - Some sources say that newly harvested, unaged garlic (meaning garlic with a high water content), is more prone to turning color; other sources say the opposite.
  
• Added presence of acid - It seems clear that the presence of acids such as lemon juice or vinegar can cause a color change, although not always.
  
• Temperature - Garlic that is pre-heated may or may not react with acid to change color.
  
• Color of garlic bulbs - Some garlic is pure white, some has tinges of purple or red; the colored garlic may be more prone to turning blue-green.
  
• There is at least one place in the world where garlic is deliberately turned into a jade-green color. For centuries the Chinese have produced Laba garlic, a jade-green pickled garlic which is an important food accompaniment to celebrating the harvest festival of Laba. If the Chinese can perfect this color change in garlic, why do we have only “accidents”?

If your garlic turned blue by surprise, you may have already researched this accident and found discussions about sulfur compounds in garlic reacting with copper present in water supplies, utensils, or copper-rich foods. There may be validity to this explanation, in which case the blue color indicates the presence of copper sulfate, not the presence of multipyrrole pigments.

Until more research is completed, here’s some helpful information to have when your garlic turns blue in your kitchen:

• Absent any sign of spoilage such as foul smell or mold, your blue garlic is safe to eat
  
• There are so many variables causing accidental garlic color change that it may be impossible for you to duplicate this surprising event in your home kitchen.
  
• No one as yet has discovered how to turn blue garlic back to white, although continuing to heat the turquoise garlic may dull it down to a pinkish-brown.
  
• When serving your dish that contains aquamarine bits of color, say nothing. Most folks, if they notice this color at all, will never ask, knowing that whatever you bring to the table is good to eat because you brought it. If someone does happen to ask why there are bright blue-green flecks of color in the dish, take them aside and tell them your secret and that you expect them to keep it: “The dish needed some color.”

Rest assured, that no matter how strange blue garlic looks, it hurts only your eyes, not your body.


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