Q: What is the procedure for storing garlic in oil or making your own homemade garlic oil? What about when you make pesto with garlic oil? Can you freeze the pesto?
— Yvonne Sprague,
Livonia, Mich.
A: The Food and Drug Administration says extreme caution must be taken when it comes to storing garlic in oil because of the threat of Clostridium botulinum, or botulism. Garlic is a low-acid vegetable and when stored in the oil under ideal conditions, it can support the growth of botulism. Ideal conditions happen when improper home canning practices or improper preparation and storage of fresh herb and garlic-in-oil mixtures take place, according to a report from the University of California, Davis.
The report listed moisture, room temperature, lack of oxygen, and low-acid conditions as factors that allow botulism to grow. (This is why you should always follow approved recipes exactly when canning.)
“Don’t do it,” says Robin Danto, MSU’s Oakland County extension educator in food safety and nutrition, says of storing garlic this way. “If you do, it shouldn’t be out of the refrigerator for more than two hours and after two days it should be thrown out.”
Danto says you won’t be able to tell whether the garlic has turned toxic: “It will not taste or look differently. It will not smell; it does not produce gas.”
When it comes to pesto, Danto says, follow the same rule, keeping the mixture refrigerated and using the pesto within two days.
You can freeze the pesto for longer storage. Danto suggests using the pesto within two months for best quality, but you can freeze it longer.
Here’s an easy way to freeze pesto: Spoon mixture into ice cube trays and freeze. Once frozen, pop out the cubes and store them in a plastic sealable freezer quality bag or container. One ice cube compartment will hold a good heaping tablespoon of pesto so you can use it according to your recipes or serve as is.
If you’re looking for a new pesto recipe to try, consider this one for Collard Greens and Kale Pesto, appearing in the July issue of Bon Appétit.
Collard Greens and Kale Pesto: Remove the stems of 1 small bunch of collard greens and 1 small bunch of Tuscan kale. In a large pot of boiling salted water, cook collards and kale until bright green and tender, about 45 seconds. Transfer to a bowl of ice water to stop the cooking and lock in the color. Drain; squeeze out as much liquid as possible (to avoid a watery sauce).
Coarsely chop greens and place in a food processor. Add 3 chopped garlic cloves, 1/2 cup grated Parmesan, 1 cup oil, 1/2 cup unsalted and roasted peanuts, 1 tablespoon finely grated lemon zest, and 1 tablespoon lemon juice; process on low speed until a coarse but well-blended mixture forms (a little texture is part of the selling point). Season with salt and plenty of freshly ground pepper. You can make this pesto 1 day ahead, cover with plastic wrap, pressing directly against surface, and chill. The pesto makes about 2 cups.
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