Rooted in multiple cultures for more than 5,000 years, garlic has had diverse roles: an offering in Egyptian tombs, a performance booster for Greek Olympians, a tool to rally strength for Roman soldiers and a smelly demon repellent in folklore stories. Hippocrates and physicians from China, India and Egypt documented garlic for treating respiratory, digestive and parasitic infections, among other ailments.
Most commonly used as a seasoning, garlic is a vegetable. The two main varieties are softneck, also known as “braiding” garlic, and hardneck. Most grocery stores carry dried softneck bulbs, which are bred more for long storage rather than flavor. Hardneck is sold as bulbs in farmers markets or specialty grocery stores and can produce garlic scapes, which are edible flower stalks with a mild garlic flavor. Bulbs include red and purple striped cultivars such as Siberian, Chesnok Red and Spanish Roja and range in flavor from mild and sweet to tangy and smoky.
In the Kitchen: Garlic’s pungency limits eating it as a raw vegetable but elevates it as an aromatic and spicy ingredient. Its strong flavor comes from the activation of the enzyme alliinase, when whole cloves are prepared, and its reaction with alliin, resulting in allicin and the formation of organosulfur compounds. Because garlic potency depends on how much alliinase is released, crushed garlic is more pungent than sliced garlic.
Cooking garlic makes it mild and savory, and a low-heat roast yields caramelized flavors. However, overly browned garlic can taste bitter, and its low concentrations of water and fructose cause it to burn quickly. Unique textures and flavors develop when garlic is smoked, pickled or aged, such as with black garlic, a soft-sticky, jammy and umami-rich ingredient popular in Asian cuisine.
A common aromatic ingredient in savory dishes, garlic headlines in classic menu items including forty-clove chicken, garlic knots, garlicfried rice, pasta aglio e olio (garlic and olive oil) and sauces such as French aioli, Greek skordalia, Lebanese toum, Italian bagna càuda and Argentinian chimichurri. Add whole roasted garlic cloves to stews and grain salads or blend it into vegetable dips, sauces or dressings.
To prepare garlic, crack individual cloves with the flat of a knife blade to loosen peels. For larger quantities, put unpeeled cloves from a bulb in a mason jar or small pot, cover with the lid and shake vigorously until skins separate. A garlic crusher or press removes the peel but may reduce the yield. If using in raw dishes, remove the green germ of sprouted cloves to avoid sharp, bitter notes that aren’t noticeable when cooked.
In the Clinic: Garlic is typically eaten in small quantities, limiting its contribution to recommended daily values of nutrients, but it offers several minerals and vitamins such as manganese, copper, selenium and vitamins C, B6 and thiamin.
Studies on the health benefits of various forms of garlic — including powder, extract and tablets — suggest it may reduce cholesterol, improve blood glucose control, support immunity, improve hypertension and reduce risk of some types of cancer. However, the variety of garlic preparation methods used in studies makes it difficult to form concrete claims about garlic’s potential health benefits and applications.
Allicin has antibacterial properties and may deactivate some influenza and rhinoviruses, and limit the formation of select bacterial toxins such as from staphylococcus. However, evidence of garlic as an antiseptic and antibacterial is often from in vitro and animal studies, so more research is needed. Because some forms of beneficial organosulfur compounds like allicin break down quickly after formation, many studies and garlic supplements contain more stable compounds such as aqueous garlic extracts, or AGE.
Allicin and some other organosulfur compounds available from garlic are temperature sensitive, as is alliinase, which can be destroyed when garlic is heated. Some research indicates a 10-minute wait after crushing garlic and before microwaving or heating allows these beneficial compounds to be formed and partially maintained. Steaming garlic, rather than frying or boiling it, may best preserve polyphenol and flavonoid content.
In Quantity: When purchasing garlic, dried bulbs should be firm, feel heavy for their size and have a tight, dry skin casing with no signs of mold or sprouting. Whole bulbs last one to two months in the pantry at room temperature, one month in the freezer and up to 14 days in the refrigerator. Individual cloves broken from the bulb can last up to 10 days.
Freeze bulbs in freezer-grade wrapping or mince cloves and coat in oil (about ½ teaspoon per clove), then freeze on a baking sheet and store in freezer-safe bags for up to a month.
For foodservice, large quantities of pre-peeled cloves are available to order in bags and can be prepared in a food processer with a little olive oil, or purchase pre-minced garlic in tubs or garlic paste in tubes. Pre-minced garlic may be pasteurized or include preservatives such as phosphoric acid and citric acid.
Garlic stored in oil can be a source of botulism and should be refrigerated and used within four days, if homemade, or frozen for later use. However, types that are produced commercially are acidified to help prevent bacterial growth.
For longer-term storage, purchase garlic in flake, granule or powdered form and substitute ⅛ teaspoon garlic powder for 1 medium-sized clove.
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