Garlic can be purchased as peeled whole cloves or minced, both stored in olive or vegetable oil. It is imperative that garlic in oil be stored under refrigeration to avoid potentially-deadly botulism bacteria growth.
Garlic Selection and Storage
When shopping, choose garlic heads that are firm to the touch, with no nicks or soft cloves. If you notice dark, powdery patches under the skin, pass it up because this is an indication of a common mold that will eventually spoil the flesh.
Store unpeeled heads of garlic in an open container in a cool, dry place away from other foods. Do not refrigerate or freeze unpeeled garlic. Properly stored garlic can keep up to three months. As garlic ages, it will begin to produce green sprouts in the center of each clove. These infant green sprouts can be bitter, so discard them before chopping the garlic for your recipe. However, if you plant the cloves and let them sprout to a height of about six inches, you can use the sprouts like chives in salads and such.
If you use a lot of garlic and wish to cut your preparation time down, you can pre-peel and store your own in olive oil in the refrigerator, but the best flavor will come from freshly-peeled cloves. Use garlic powder, garlic salt, and garlic extract (juice) only as a last resort.
How to Peel Garlic
To peel a garlic clove, place it on a cutting board on its side, and gently press down quickly with the flat side of a butcher knife. The skin should then easily peel off. If you find the skin clinging desperately to the clove, congratulations, you have fresh garlic. As garlic ages, it shrivels inside the skin, making it easier to peel.