This garlic clove turned blue-green when pickled with onion (and green
cherry tomatoes.) Though poisonous-looking, it is safe to eat. The hue
comes from chlorophyll-like chemicals in the onion and garlic.
Last summer, when I pickled a few pints of green cherry tomatoes, the cloves of garlic tucked in the jars turned a lurid blue-green—the sort of weirdly beautiful shade that copper turns when exposed to weather. I was so alarmed that I emailed Rick Field of Rick’s Picks, who had given me the recipe. ‘Is it poisonous?” I asked. “Will I die if I eat it?” “Don’t worry,” said Rick “That happens all the time. It’s perfectly safe to eat.”
In today’s New York Times (“The Curious Cook: When Science Sniffs Around the Kitchen,” Wednesday, December 6, 2006, pp. D1 and D11), Harold McGee writes about his own experience with another bizarre color change. “…I was really rattled the first time I pureed raw garlic, onion and ginger together in the blender to make chicken in yoghurt from Madhur Jaffrey’s “Invitation to Indian Cooking.’ When I fried the puree, the entire mass turned turquoise blue.”
McGee notes that in northern China, aged fresh garlic is left in vinegar for a week to make an “intentionally intensely green” Laba garlic pickle traditionally served with New Year’s dumplings. According to chemists at the China Agricultural University in Beijing, aged garlic is saturated with a chemical that turns garlic green when released by the acetic acid in the vinegar. “The pigment itself turns out to be a close chemical relative of chlorophyll, which gives all green leaves their color,” he writes.
The color change in garlic and garlic-onion blends is created, McGee says, by the “same handful of sulfur compounds and enzymes that give the allium family its unique pungent flavors. Under the right conditions, these chemicals react with each other and with common amino acids to make pyrroles, clusters of carbon-nitrogen rings.” Essentially, these rings absorb different wavelengths of light and may appear green or blue, depending on their structure. To eliminate the blue hue of an onion-garlic blend, simply raise the heat in the pan—it will turn, according to Ms. Jaffrey, “a more acceptable pinkish-brown...”
Harold McGee is the author of On Food and Cooking: The Science and Lore of the Kitchen, a superb reference book which includes a excellent analysis of the flavor components in spices and herbs. His website is www.curiouscook.com. Today’s article is the first in a series of columns on the science of cooking, also called “The Curious Cook,” which McGee will write for The Times.
Comments (9)
This was so helpful. I have been pickling garlic cloves for years simply by adding vinegar and salt and keeping it refrigerated. But when some turned green, I threw them out. Read about boiling the brine first, but they still turned green leaving me to think the cloves were not good. This is good news. Thanks
Posted by Teddy Picard | February 2, 2009 8:29 AM
Posted on February 2, 2009 08:29
Oh thanks a lot..i was preparing chicken the same way as mentioned above . It was alarming to see onion ginger garlic mixture turning green . Thnx to ur explanation..am relieved
Posted by monica | March 13, 2009 12:26 PM
Posted on March 13, 2009 12:26
I use pickle juice, add fresh dill, then refrigerate and i was having the same problem with the garlic turning color. Glad to know that it is okay and will not hurt us. Thank you!
Janet
Posted by janet payment | February 1, 2010 11:28 PM
Posted on February 1, 2010 23:28
That little Info was just was was looking for because I am trying to make a garlic extract and the vodka and garlic was starting to turn green..
Posted by Anonymous | October 15, 2010 11:55 AM
Posted on October 15, 2010 11:55
what can I do to prevent the garlic from turning green when in vinegar in fridge
Posted by Helen Strydom | March 22, 2011 4:55 AM
Posted on March 22, 2011 04:55
Sorry, no answer to that problem yet. The good news, as you can see, is that it's perfectly safe to eat. But why not take advantage of the color? Pickled green garlic, impaled on a skewer, would be a great ingredient for a spicy bloody mary...
Posted by courtenay | April 17, 2011 1:30 PM
Posted on April 17, 2011 13:30
what if the picked garlic bulbs have gone green in the sun?
Posted by paul | February 19, 2012 9:39 PM
Posted on February 19, 2012 21:39
I've never seen that happen, but as long as they're still edible there shouldn't be a problem with pickling them.
Posted by Courtenay | February 20, 2012 7:12 AM
Posted on February 20, 2012 07:12
I hope this is the same for dehydrating garlic because about half of my 2lbs turned green! Does anyone know?
Posted by Kahla | March 1, 2012 8:02 PM
Posted on March 1, 2012 20:02