A good bottle of olive oil is a requirement for just about every kitchen. From drizzling over vegetables or meats to crafting salad dressings and bread dips, a little olive oil can make your cooking sing. But how much do you need to spend for a quality olive oil, and how long will it last once opened? Is extra-virgin olive oil all that it purports to be?
Dan Flynn, executive director at the University of California at Davis Olive Oil Center; and Darrell Corti, a frequent olive oil competition judge, provide answers.
The olive harvest typically begins in early November, and more consumers are turning to olive oil for their culinary needs. According to Flynn, about 2 million gallons of olive oil are expected to be produced statewide in 2012 about double the amount from the previous year. Like wine, sorting through rows of olive oils at the store sometimes feels like a guessing game. Quality can range greatly, as will flavor profiles, which span from fairly neutral to very pungent.
"The quality of olive oils are based on the variety (of olive used), the time of their picking and the type of extraction used," said Corti. "All oils have a flavor character that's pungent and bitter. That's the normal flavor component of an olive. You want the oil to retain its bitterness and pungency."
So, let's start with shopping.
Let's say there's a great price on a gallon of olive oil that seems hard to pass up. Well, unless you plan to cook a lot with olive oil and use it fairly fast, it's best to buy these oils in smaller amounts.
The best olive oil is the freshest olive oil, and as with wine, oxygen is an enemy. Once a bottle is opened and oxygen gets introduced in the bottle, that's the start of an oxidation process that leads to declines in flavor and aroma. Olive oils contain fatty acids that can help fight off oxidation, but in the end, oxygen will always win. Plan on using up that bottle within weeks.
"As you use the oil, you're going to add some head space into the bottle, and that's how oil gets oxidized," said Flynn. "I try and use an oil as quickly as I can. Six to eight weeks can be good. If you can't use it in that time, you're maybe buying too big a container."
Unopened bottles of olive oil can last up to two years if stored properly, and their flavors can soften with extended time in the bottle.
"Keep them in a cool, dark place and buy them often," said Corti.
Heed the harvest date stamped on the bottle. This assumes your olive oil bottle comes stamped with a harvest date. If not, that's a key indicator that your oil likely isn't of the best quality. Some olive oils might have a "best by" date instead, but harvest date will be a better indicator of how fresh your oil may be.
"A 'best by' date is important as well, but we've found in some studies that a lot of that oil has already gone south," said Flynn. "They had some rancid and off flavors, butwere within the 'best by' date. Look for the harvest date. Every olive oil, no matter how good it starts out, is going to decline."
The term "extra-virgin" is supposed to connote the utmost in olive oil purity. By definition, an extra-virgin olive oil must be free of defects, while exhibiting a certain measure of fruitiness. The oil must also be extracted solely by mechanical means, and no solvents may be used during processing, among other factors. Such standards are set by the International Olive Council, the United States Department of Agriculture and other bodies. Tasting panels also are used to determine if an olive oil is indeed extra-virgin.
Plenty of controversy has surrounded "extra-virgin." A UC Davis Olive Center study found that 69 percent of imported oils in the American marketplace listed as "extra-virgin" didn't meet set standards once sampled by a UC Davis and Australian research team. Ten percent of California olive oils didn't meet the extra-virgin test. The study found defects caused by oxidation, processing flaws and adulteration with cheaper oils.
That's to say, don't buy an olive oil by the term "extra-virgin" alone.
"Not all extra-virgin olive oils are created equally," said Flynn. "It is something to look out for, but people need to be smart. You can have a bland oil that will pass that test. Also, if you find an oil that's made from multiple countries, there's not a good track record from tests that it will be very good."
Don't judge an oil by its color
Olive oils come in many shades, from golden yellows to deep, grassy green. But unlike wine, in which evaluating color is a key part of any analysis, there's no connection between the lightness or darkness of an oil and the strength of its flavor.
"The color of olive oil has nothing to do with the taste of the oil," said Corti, in a firm tone. "What you do want to pay attention to is its clarity."
That's to say, even light-colored olive oils can boast intense flavors.
Olive oils can be found across the price spectrum, from a $4 bottle of Star at the supermarket to imports and other meticulously crafted oils that cost upward of $30. Still, price alone doesn't necessarily determine an oil's quality. In a recent test of 23 olive oils by Consumer Reports, only two olive oils were rated "excellent": Mc-Evoy Ranch olive oil ($22) and Trader Joe's California Estate olive oil ($6).
Cooking with olive oil
Unless you have money to burn, using high-quality olive oil for cooking and frying somewhat defeats their purpose. These oils generally have pronounced flavor profiles, and heat will just strip away much of their taste. They're best used for drizzling over vegetables or carpaccio, or as the basis for salad dressings and dips for bread.
Rustic olive oil cake with honey syrup
Makes one 9-inch cake; serves 10
Vegetable oil spray for the pan
2 cups all purpose flour, plus more for the pan
½ teaspoon baking powder
½ teaspoon baking soda
1 teaspoon kosher salt
1¼ cups whole milk at room temperature
¼ cup Grand Marnier
¼ cup fresh orange juice
Grated zest of 1 lemon (1 tablespoon plus 1 teaspoon)
3 large eggs at room temperature
2 cups sugar
1 cup extra virgin olive oil
½ cup honey; ½ cup sugar; ½ cup water; 1 clove; 1 strip of orange or lemon zest, about ½-by-4 inches, cut with vegetable peeler
Preheat the oven to 375 degrees. Spray 9-inch round cake pan with vegetable oil spray, line bottom with parchment paper, then spray the paper. Flour the pan, shaking out the excess. Set the cake pan aside.
Sift together the flour, baking powder, and baking soda. Stir in the salt. Set the dry ingredients aside.
In a small bowl, combine the milk, Grand Marnier, orange juice and lemon zest. Set the wet ingredients aside.
Put the eggs and sugar in a large bowl and whisk by hand with a balloon whisk until well combined and smooth. Gradually add the olive oil in a steady stream while whisking the egg mixture.
After you have emulsified the oil into the egg mixture, start adding the dry ingredients in three additions, alternating with the wet ingredients in two additions, beginning and ending with dry. As you make each addition of dry and wet ingredients, whisk by hand just until the batter is smooth, without overbeating, before adding the next. Scrape down the bowl as needed.
Pour the batter into the prepared pan. Bake the cake until deep golden brown, slightly domed, and possibly cracked on top, about 70 minutes. A skewer should come out clean, but with a few moist crumbs.
Meanwhile, while the cake is baking, make the syrup. Combine the honey, sugar, water, clove, and citrus zest in a small saucepan over medium-high heat. Bring to a simmer, stirring to dissolve the sugar and adjusting the heat as necessary to keep the liquid at a simmer. Simmer until reduced by almost half and as thick as a light syrup, 10 to 12 minutes. (You should have a little more than ¾ cup of syrup.)
Cool syrup to room temperature. Remove the clove and zest from the syrup and discard. Drizzle each cake slice generously with honey syrup and dollop with cream, if desired.
This recipe is from "The Dahlia Bakery Cookbook: Sweetness in Seattle," by Tom Douglas (William Morrow Cookbooks, $35).
Tour of Sciabica olive oil plant in Modesto.