Published January 1, 2013. From Cook's Illustrated.
Want to mellow raw garlic's harsh bite? Just a few minutes in the microwave will do the trick.
Many cooks like to temper the harsh bite of raw garlic before adding it to foods like pesto, hummus, and salad dressing—but there’s no end to the suggestions for how to do that. We tested four methods: blanching whole cloves in milk for 5 minutes, blanching them in water for 5 minutes, microwaving the cloves until warmed through, and toasting them in their skins in a dry skillet until lightly browned.
Both forms of blanching worked equally well, as did microwaving. Toasting was the least effective in mellowing out garlic’s taste. Here’s why: Garlic’s sharpness is caused by a sulfur-containing molecule called allicin. Allicin is produced through an enzymatic reaction by the enzyme alliinase, only after the cell walls of the garlic are damaged during cutting or chopping. To deactivate alliinase, you must raise the clove’s temperature to 140 degrees or above—which both microwaving and blanching accomplished (the type of liquid used is irrelevant). With light toasting, only the outer layers of the cloves got sufficiently hot to turn alliinase inert.
For simplicity’s sake, we prefer heating garlic cloves in the microwave to blanching them. Microwave the cloves in a small bowl for 2 to 3 minutes, or until warm to the touch but not cooked.