Published September 1, 2009. From Cook's Illustrated.
California growers have spent the last two decades developing extra-virgin olive oils that might rival the best of Europe. Is it time to stop importing foreign oil?
In 1976, the world was stunned when California wines trumped French contenders in a blind tasting by French wine experts, an event now known as the Judgment of Paris. These days, it’s California’s olive growers who are working to make a product that could compete with Europe. Over the past 20 years or so, growers around the state, guided by experts at the University of California, Davis, have been planting olive trees, learning the best practices for harvesting and blending, and experimenting with a variety of olive presses, all in an effort to create great domestic extra-virgin olive oil. Last year, U.C. Davis opened the Olive Center, with 30 faculty researchers, acres of olive groves, and a new olive press—all with a focus on oil.
Olives are not new to California. Franciscan monks planted olive trees as they established Catholic missions throughout the area in the 1700s. But until recently, most California olives were canned for eating rather than pressed for oil. Today, California produces less than 1 percent of the 70 million gallons of olive oil consumed each year in the United States—a mere toehold that industry proponents hope to expand. Since the key to extra-virgin olive oil is freshness—its flavor degrades over time, even when sealed in a bottle—the potential benefits of buying domestic oil that doesn’t have to be imported and waylaid by customs are built in. Wondering if California already sells olive oils as good as our favorite imports, we anonymously purchased 10 extra-virgin oils from the state’s largest and most established producers and tasted them blind.
For comparison, we included a bottle of our favorite imported oil an extra-virgin olive oil from Spain that sells for about $19 per half liter. The California oils in our lineup range from $12 to $37.33 per half liter, plus shipping, though a few producers ship for free. (Some California growers are working on driving prices even lower so that they can compete in supermarkets against mass-market imported oils. Since harvesting the olives is the biggest production cost, these growers are experimenting with a new trend that is revolutionizing the industry worldwide, so-called super-high-density planting which also entails mechanical harvesting.) Tasters sampled the oils plain, with green apples to cleanse the palate, and on a crusty baguette with sea salt. We don’t generally cook with extra-virgin oil because its unique flavors and aromas dissipate with heat.
As to the single “best” flavor profile for extra-virgin olive oil, experts disagree—it would be like choosing the single best type of wine. While many olive oil novices shy away from bitter oils, tasting experts consider bitterness one of the three main positive attributes of extra-virgin oil, along with fruitiness and pungency. Olive oils earn high scores from international tasting panels for having a harmonious balance of these three qualities. They can be marked down for moldy, musty, fermented, or rotting-olive notes or flatness, among other possible flaws.
There are hundreds of varieties of olives. Each contributes a different typical flavor, but even the same olive can produce very different oils depending on the soil and climate where it was grown, the weather during the growing season, and its ripeness when picked. Deciding when to harvest is a critical skill for olive oil makers. Earlier-harvested olives tend to yield a greener, more bitter oil that is rich in polyphenols (a group of antioxidant compounds that lend color and flavor to plants). Later-harvested, riper olives usually create mild, buttery oil, with much lower polyphenol levels. In California, harvest can begin as early as late September and run through January.
The best olive oil is pressed soon after harvesting. Scrupulous oil makers use tree fruit (rather than overripe olives that fell off the tree onto the ground) that is picked carefully and pressed quickly (ideally within 24 hours), before the olives begin to rot and ferment. Pressing and storage equipment must be kept very clean, or olive oil will pick up off-flavors. In other words, if the olives are not handled correctly and pressed quickly under pristine conditions, there will be flavor defects, and the oil will not qualify as true extra-virgin.
The oil maker can bring out certain characteristics depending on the choice of press. For example, olives may be stone-crushed or fed into a hammer mill or a metal-toothed blade mill. Oil makers can gently boost the bitterness in a too-mild olive by using metal-toothed blades that cut into the skin, releasing polyphenols. Or they can produce a milder oil by selecting a stone mill; its crushing motion extracts fewer polyphenols. Some growers even use a combination of presses.
Whether to blend the oil is another key choice. Like wine, olive oil can be made from a single varietal or a mix. Blends can be created in the field, with olive trees that are planted and harvested and their olives pressed together, or in the mill, where an expert mixes batches of oils to create a particular flavor profile. European olive oils are often blends; the types of olive are listed in small print on the label, if at all. By contrast, California oil producers often focus on a specific type of olive and may sell multiple oils each year highlighting different types (for example, a choice of an Ascolano, an Arbequina, or a Miller’s Blend).
The producer must also decide whether to filter the oil or leave it unfiltered. Unfiltered oil contains more flavorful olive particles, but these shorten the shelf life of the oil, as they are prone to spoilage.
Finally, the storage method makes a significant difference. Olive oil stays freshest when protected from air, light, and heat in nonreactive stainless steel tanks, topped with an odorless and inert gas to prevent oxygen exposure and bottled only on demand. (Many of the oils we tasted were bottled on demand or in very small batches, making them far fresher than the olive oil sold in the typical supermarket or gourmet store.) The shelf life of bottled olive oil depends on how well the oil was protected from air, heat, and light and can range from as few as three months up to 18 months after the bottle is opened. Why? Different oils age differently even when stored properly. Some olives naturally contain more antioxidants, which resist the oxidation that causes rancidity.
Far from having one typical flavor profile, the California oils we tasted featured a range of styles. Although the state’s first olive oil producers favored Tuscan olive varieties and picked them early in the season for a green, bitter profile that mimicked Tuscan oils, California oils today run the gamut from buttery and mild to pungent and robust. With many different microclimates in the state, California olive producers have experimented with olives that grow well in parts of Europe that have similar climates. (Experimentation and collaboration are hallmarks of the California olive oil industry.)
What did our tasters conclude? The top-ranked oil across the board was still the Spanish oil that our tasters praised for its full, fruity, well-balanced flavor and low bitterness. But the real surprise was that a domestic challenger ranked just below it. This extra-virgin oil, made from Arbequina olives, won raves for its fresh, sweet, fruity flavor and pleasing hint of bitterness.
Based in the northern California city of Oroville, this olive oil company is the largest North American producer of olive oil and one of the pioneers in cheaper growing and harvesting methods. In addition to lowering production costs, their high-density planting and all-mechanical harvesting helps capture fresh flavor, since olives can be picked and sent to the press in just 90 minutes. Most olives around the world are still harvested by hand. Traditionally, nets are spread under the trees, and laborers use wooden rakes to pull off the olives or employ a machine that shakes the trunks so that olives fall onto the nets, which are then loaded into bins for travel to the press. This process is time-consuming, labor-intensive, and costly. When acres of olives ripen at once, as they tend to do in hot climates like in Spain or Tunisia, olives may sit around fermenting as they wait to be pressed. This is the source of one of the chief flavor defects in olive oil, an attribute experts term “fustiness.”
Fresh olive flavor is one of the qualities our tasters found most appealing in our highest-ranked oils. The oils we bought were harvested no earlier than fall 2007, but most of our top-ranked oils were from the more recent harvest of 2008, pressed a scant few months before we tasted them in March 2009. (Olive oil usually is placed in a holding tank for a month or two before bottling; it takes that long for most of the olive sediment to settle to the bottom of the tank for removal and for the flavors to meld and mellow.) We didn’t intentionally set out to buy olive oil from two different harvest years; when you place an order, you get the oil available for sale at that time. If stored properly, the previous year’s harvest will still be in its prime.
Our tasters also preferred unfiltered oils. Filtering removes fine, suspended olive particles and clarifies the oil but also removes some of the fresh olive flavor tasters enjoyed.
As for specific olive preferences, our tasters liked the flavor of the Arbequina olives—which happens to be one of the four olive varieties blended in our imported olive oil winner. Common in Spain, Arbequina has recently become one of the most-planted olive varieties in California, both for its fruity, well-balanced flavor and because it is suited to super-high-density planting. Oils made with typical Tuscan varieties scored less favorably with our panel, possibly because they have a more bitter, pungent profile, which is an acquired taste. Sevillano olives are traditionally canned as eating olives, but when pressed create exceptionally fruity oil.
Our imported oil winner is still the test kitchen favorite. Like many of the California oils we tested, it is made by a family-run business that maintains quality by owning and controlling every aspect of production. The company picks and presses its olives within 24 hours, hand-picking as well as using tree-shaking machinery. After processing the premium oil as one brand, the company re-presses those olives and sells the remaining oil at a lower price, under a different brand name. Finally, our imported winner is bottled only when distributors place an order, and once the new harvest is in, any oil from the previous year’s harvest remaining in storage is sold off under its lower-priced label. For now, we’re convinced that Europe still maintains a stronghold in this intercontinental oil battle, but the California growers—particularly the folks behind our favorite, relatively affordable oil—have clearly struck something promising. As they further refine their products, we’ll look for the day when we can pick up California olive oil in the supermarket, right next to the imported oils.