sa国际传媒

Skip to content
Join our Newsletter

Ask Eric: What makes garlic go blue-green?

Chemical reaction with copper can cause the mysterious colour change
img-0-7213921.jpg
Bits of blue cheese and roasted garlic give this potato and leek soup its earthy flavour.

Dear Eric: Can you tell me why garlic sometimes turns a blue-greenish colour when I cook it? Is it safe to eat when that happens?

Cheryl

Dear Cheryl: According to a few sources, garlic is known to contain sulphur compounds that, if not inactivated by heat, can react with minute traces of copper to form copper sulphate, a blue or blue-green compound.

A comprehensive article on the subject at whatscooking america.net suggests that the amount of copper needed for this reaction is minuscule, and is frequently found in tap water or in metals used in some cooking utensils.

According to the article, another reason fresh garlic might change colour is because it was picked before it was fully mature and wasn't properly dried. That type of garlic, when added to an acidic ingredient, such as wine, vinegar or lemon, or when cooked with an ingredient that naturally contains copper, such as butter, can also take on a blue-green colour.

In both cases noted above, the garlic is safe to eat, but not visually appealing.

In Harold McGee's book On Food and Cooking: The Science and Lore of the Kitchen, he says when using garlic in pickles, you can minimize the risk of discolouration by blanching it before pickling.

Fortunately, I didn't have any issue with my garlic turning colour in the two tasty, garlic-rich recipes below.

Leek and Potato Soup with Roasted Garlic and Blue Cheese

This hearty soup is definitely for garlic lovers - a whole bulb is used in it.

That might sounds like a lot of garlic, but its flavour is mellowed and sweetened by roasting the garlic before stirring it into the pot. Make a fine lunch of this soup by serving it with some crusty bread and a glass of white wine, such as Gew脙录rztraminer or Riesling.

Preparation time: 20 minutes

Cooking time: 75 to 85 minutes

Makes: 4 servings

1 large whole garlic bulb

1 tsp olive oil

2 Tbsp olive oil

1 medium leek, white and pale green part only, halved lengthwise, washed, then sliced

2 Tbsp all-purpose flour

4 cups chicken or vegetable stock

1 medium baking potato, peeled and cubed

1/2 tsp dried tarragon

- salt and white pepper to taste

100 grams blue cheese, crumbled

1 Tbsp chopped fresh parsley

Preheat oven to 325 F. Trim a little from the top of the garlic bulb to expose the tip of each clove. Place garlic cut side up in a small baking dish. Drizzle with the 1 tsp olive oil. Roast the garlic, uncovered, 50 to 60 minutes, or until very tender. Cool garlic a few minutes, and then squeeze the cloves out of their skins and on to a cutting board. Coarsely chop the garlic.

Heat the 2 Tbsp oil in a medium pot. Add the leeks and cook until softened, about 3 or 4 minutes. Stir in the flour until well-combined. While stirring, slowly pour in the stock.

Add the garlic, potato and tarragon and bring the soup to a simmer. Simmer 15 minutes, or until the potato is very tender. Pur脙漏e the soup in a food processor or blender, or in the pot with an immersion blender. Return soup to a simmer; season with salt and pepper. Ladle into bowls, top with cheese and parsley and serve.

Garlic-Stuffed Chicken Legs With Pan Gravy

This garlic-rich chicken dish is from my soon-to-bepublished new book, Everyone Can Cook Everything. The chicken goes great with mashed potatoes and buttery, steamed green beans.

Preparation time: 20 Minutes

Cooking time: 50-60 Minutes

Makes: 4 servings

4 large chicken legs

6 garlic cloves, thinly sliced

1 tsp dried herbs, such as sage, thyme and rosemary

- salt and freshly ground black pepper to taste

2 1/2 cups chicken stock 3 Tbsp all-purpose flour

Preheat the oven to 400 F.

Carefully lift the skin from the thigh end of a chicken leg. Stuff a quarter of the garlic slices underneath, pushing them to different points around the leg. Repeat with the remaining legs.

Place the chicken in a stovetop and ovenproof pan. Sprinkle the herbs over the chicken and season with salt and pepper. Bake, basting with the pan juices occasionally, for 45 to 50 minutes, or until cooked through.

When the chicken is ready, remove it from the pan and keep it warm in an oven set to 200 F.

Remove excess fat from the pan and set over medium heat.

Pour in 2 cups of the stock. Mix the flour with the remaining 1/2 cup of stock until it is lump-free. Add it to the pan in a slow stream, whisking constantly. Bring the gravy to a simmer and cook until it thickens and the flour is cooked through. Season the gravy with salt and pepper. Serve the chicken with the gravy alongside.

Dear Eric: Could you please settle an argument? When using aluminum foil to wrap veggies for the barbecue, does the shiny side go to the inside or the outside?

Sharron Manick

Dear Sharron: To get the answer to your question, I went to the website of aluminum foil maker Reynolds, reynoldskitchens.com, a great resource for queries related to that product and others, such as parchment paper.

The company says that it makes no difference which side of the aluminum foil you use - both sides do the same fine job of cooking, freezing and storing food.

The website notes the difference in appearance between dull and shiny is due to the foil manufacturing process. The side coming in contact with the mill's highly polished steel rollers becomes shiny, while the side not coming in contact with the heavy rollers comes out with a dull or matte finish.

Other sources do suggest that, for example with your package of vegetables, if the shiny side of the foil is on the outside, it could reflect the incoming heat, slightly slowing the cooking process. But most sources I checked said that it would make very little or no difference to the cooking time.

So, Sharron, if someone prefers the shiny side in, and the other the shiny side out, they both would not be doing anything wrong.

Eric Akis is the author of the bestselling Everyone Can Cook series of cookbooks. His columns appear in the Life section Wednesday and Sunday. Send questions by email or to Ask Eric, sa国际传媒, 2621 Douglas St., Victoria, V8T 4M2.

[email protected]