Everything You Need to Know About Buying, Storing and Cooking with Olive Oil
Olive oil is a beloved kitchen staple, whether it’s used as a condiment, cooking oil, marinade or something else entirely.
But where did this all-important ingredient come from? And how do you select the best bottle? Here’s everything you need to know about olive oil.
A Brief History of Olive Oil
The International Olive Council (IOC) originated in Madrid in 1959 under the United Nations. It sets industry and sustainability standards for olive tree growth and olive oil production.
According to the IOC, “the origin of the olive tree is lost in time,” but it likely dates from the first Mediterranean societies. It’s believed that the trees dispersed, or propagated, gradually throughout the Greek isles, Italy, Spain and Portugal between the 16th century B.C.E. and 45 B.C.E.
Olive farming came to the United States and Mexico through the West Indies, where it was introduced by Spanish colonists in the 15th century.
What are Olives, Exactly?
An olive is a drupe, fleshy with a single, central seed. Its sugar content is less than other drupes like cherries and plums, and its oil content ranges from 12–30%, depending on when it’s harvested. Roughly 139 varieties of olives can be pressed for edible oil.
What Does Extra-Virgin, Fresh-Pressed, and First Cold Press Mean?
Ann Sievers, owner, olive grower and miller at IL Fiorello Olive Oil Company in Fairfield, California, says that an extra-virgin olive oil (EVOO) certification label can be a sign of quality for consumers, as the oil meets specific standards and has no sensory defects.
“Extra-virgin olive oil [must] be nothing but olives,” says Sievers. “Therefore, by definition, infused olive oils cannot be labeled ‘extra-virgin.’” EVOO also has the lowest acidity level of all the virgin categories. Acidity levels measure free fatty acids. These form during olive oil production, and do not confer the same health benefits as oleic acid, an omega fatty acid that is the key to extra-virgin olive oil’s health benefits.
The IOC, the United States Department of Agriculture (USDA) and other state entities have established sensory and chemical standards for EVOO certification.
Il Fiorello, California Olive Ranch and many other producers send their oils to organizations like Applied Sensory for evaluation. When tasting olive oil, a slight burn in the back of the throat is often a good indication of a certified EVOO’s bitterness and pungency. These signal phenolic compounds like oleocanthal, the source of the oil’s anti-inflammatory and antioxidant properties.
Both Sievers and Cara Gambini, owner of Texas Hill Country Olive Co. in Dripping Springs, says terms like “first cold press” and “fresh-pressed” aren’t as helpful as an EVOO certification.
First pressed means that olives have been pressed once.
First cold pressed means that the pressing was done without the intervention of heat to aid extraction. Heat may yield more oil from the olive, but it dilutes oleic acids that contain the oil’s intrinsic health benefits. Today, all certified virgin and EVOO are pressed at temperatures no warmer than 80.6°F (27°C).
“First cold pressed hearkens back to the history of how olive oil has been made for a long time, but it has nothing to do with the way we make it today,” says Sievers.
Fresh-pressed may not represent what you’d think. Olives are harvested just once a year, says Gambini. So a bottle that says “fresh-pressed” may have been produced months prior to sale.
These terms may signal that the producer took steps to create an extra-virgin oil, she says, but they don’t verify the oil’s quality in the same way as EVOO certification.
Is Olive Oil Good for You?
Caitlin Carr is an Oregon-based clinical registered dietician who specializes in chronic disease management and nutritional support. She points to two studies that link extra-virgin olive oil with numerous health benefits.
For instance, a 2019 study published in the Journal of Agricultural and Food Chemistry suggests that oleocanthal offers the same anti-inflammatory benefits as non-steroidal medications like ibuprofen.
Carr also shares a 2018 study published by the International Study of Molecular Sciences that claims the antioxidants in olive oil’s phenolic compounds can reduce the risks of cancer as well as neurodegenerative and cardiovascular disease.
Leslie Bonci, owner of Active Eating Advice and a registered dietician, Master of Public Health, and certified specialist in sport dietetics, says the monounsaturated omega fatty acids in olive oil can help lower LDL cholesterol, which can lead to a buildup of fatty plaque in the arteries.
Carr says olive oil, a primary ingredient in the Mediterranean diet, also helps with cardiovascular health when eaten with fruits, vegetables, lean meats, plant proteins, legumes and whole grains.
How Do You Properly Store Olive Oil?
“Definitely not in the refrigerator,” says Sievers. She recommends that you keep olive oil in a cool, dark cupboard.
Mary Mori, food scientist and vice president of technical services for California Olive Ranch, says that the four main threats to cooking oil are time, heat, oxygen and light.
“Once a bottle of olive oil has been opened, you want to use it, ideally finishing it within six to 10 weeks after opening,” says Sievers. Oxygen exposure can damage an oil, especially as bottles are opened and closed several times.
Gambini cautions against olive oil bottled in clear glass or plastic. A dark bottle will filter out harmful UV rays. She also advises to keep olive oil away from heat sources like stoves or windowsills.
Mori recommends buying the right size bottle based on your usage rate. A bigger bottle is fine if you plan to finish it quickly but select smaller bottles if your usage isn’t as frequent. Some companies, like California Olive Ranch and McEvoy Ranch in Petaluma, California, have developed bags that fit into a box, which helps protect the oil from oxygen and light exposure.
How Do You Buy the Right Olive Oil?
Sieversurges consumers to select oils while they’re young—the younger the better—with a harvest date on the bottle. Ideally, the label should list the date that the oil passed its sensory exam for EVOO certification.
Diane Kochilas, chef, cookbook author, creator and co-producer of the PBS series My Greek Table, says that consumers can also look for an indication of acidity level. The lower, the better.
“An acidity level of 0.8% is average, 0.5% is good and 0.3% or less is considered the highest quality,” says Kochilas.
Gambini suggests that you stay away from light- pure- or pomace-grade olive oil.
“[They] are refined and don’t have the flavor or health benefits to stand up to an EVOO,” she says.
Marisa Moore, registered dietician and author of the forthcoming book Plant Love Kitchen, says to look for olive oils from a single source or location. Also, choose bottles that have been pressed within the last year.
Moore recommends paying attention to flavor profiles within olive oils, and select bottles that will complement specific recipes.
Taggiasca, a variety milled by IL Fiorello, is grassy and herbaceous. “You might use a fragrant, fruity extra-virgin olive oil to bake a cake or make ice cream, and one with a bit more spice to drizzle on fresh vegetables or to top hummus,” says Moore.
Kochilas curates an online shop with a portfolio of Greek olive oils.
“There are some excellent oils from Corfu and Halkidiki in the north, too,” she says. “The main oil olive variety in Greece is the Koroneiki, but other varieties also produce delicious oils. Manaki is one to look for too, and is found in parts of the northern Peloponnese.”
Gambini says to look for oils at farmers markets or other local gourmet stores, seek out olive orchards and sign up for mailing lists of artisanal producers to keep apprised of their next harvest.
“You’ll get the freshest oil first,” she says. “And if you’ve never tried an olio nuovo, you haven’t lived.”