What to look for, and why it matters.
People will ask me what the most important thing about olive oil is, and I tell them this: the most important thing is everything. All we see is a bottle on a shelf, but olive oil is the product of many kinds of processes and variables and sub-components.
Some people think that green olives and black olives are different species—this is not true. The color of the olive reflects the stage of maturation. All olives start their life green, and ripen to a deep purplish-black. The earlier you harvest the olives—when they’re primarily green—the less oil is in the olive, but the stronger and more dynamic the oil will be. The later you harvest the olives—when they’re dark purple—the more yield you’ll get, but the oil will be more neutral and mellow. Different producers do it different ways depending on what they want their oil to taste like: some harvest half the group early and half late, and get a more robust and delicate oil from the same olive cultivar just by staggering the harvest.
In the kitchen, it’s great to have options all along the spectrum—sometimes you want a strong, peppery oil, and sometimes you want a sweet, delicate oil. Here’s what you need to know in order to choose the right bottle.
1. The first thing I look for is the harvest date. Oil mellows out over time, so you always want your oil as fresh as possible. There are three primary ways of harvesting olives: hand-harvesting, industrial harvesting, and harvesting from super-high-density planting. With a hand-harvest, you’re physically combing the olives off of the trees, and then getting on your hands and knees and removing any sticks, twigs, and bad olives. If enough of those things get into the batch, you’ll have a defective oil. An oil that’s $25 or higher has usually been hand-harvested. On the other hand, industrial producers—who have like, three hundred thousand trees—will use machines for their harvest. A common problem with this method is that branches fall, whole parts of trees are ripped out, bugs fall in, and the olives sit in piles for long periods of time before heading into the mill. However, you can harvest a tree in sixty seconds, so the price point is going to be much cheaper. The most modern method, which is happening in Spain, California, and Australia, uses something called super-high-density planting. They found three olive cultivars that are dwarfable—the Arbequina, the Arbosana, and the Koroneiki—and they plant the trees in hedgerows, pruning the trees so that the olives grow closer to the central trunk. They go over it with harvesting equipment that combs the olives out, and then the olives go on a kind of conveyer belt. It’s like the industrial harvesting, but with more thought. Anyway, an oil bottled with a harvest date telegraphs that the producer knows that that data point is important to your experience of his or her product.
2. Just because it’s green doesn’t mean it’s going to taste good. Greener doesn’t mean better, and it definitely doesn’t mean fresher. Some producers will actually put leaves in the olive press to increase the chlorophyll content, which is so not cool. I know some producers that use dark bottles internationally and clear bottles only for the U.S. market, because they know the American people think, Ooh, green means fresh. People are laughing at us. Buy your oil in a dark bottle, because light causes the oil to oxidize.
3. There are two methods you want to look out for: the cold-pressed method and the cold-extracted method. In both of these, “cold” actually means that everything is kept below 81.9°F, which is the point at which the aromas start to lift off of the olive paste. With the cold-pressed method, traditionally a horse or a donkey would be hooked up to a wheel and they would trot in a circle, and out would come olive juice: part oil, part water. It would sit in vats overnight, and the oil would rise to the top. The process hasn’t really changed, except we don’t use animals to do it anymore. Now, the cold-pressed method is dying out in favor of the cold-extracted method, where the olives go through a series of centrifuges and vacuums and are never exposed to oxygen. More and more people are starting to do it this way: It’s faster; it’s more sanitary; it’s cheaper; the olive paste never oxidizes; and you can get a sharper oil from a more ripe fruit. I think both ways are great—but if you’re going for an oil with a longer shelf life, the modern way is better. And, obviously, it should be extra-virgin.
4. Some people say that unfiltered oil is better, but that’s not always the case. If it’s fresh, unfiltered oil can be great, but with filtered oil you get a longer shelf life and a more focused flavor profile. I’ve tasted oils back-to-back that are filtered and unfiltered, and it blew my mind. The unfiltered one can be a little hazy—and then you taste the filtered one, and you’re like, There’s the flavor. Again, unfiltered oils thrive when very fresh, and if there’s any doubt in your mind about that, opt for filtered.
5. I’m not a wine expert, but people see a specific grape from a specific region from a certain year, they know what they’re getting. The same is true for olive oil. You want to know the region the oil comes from, and the olive it’s produced from. With that information, I can make an educated guess as to what that oil might taste like. If the bottle just says “extra-virgin cold-pressed product of Italy” without any other information, alarms should start going off. A great way to study olive oil is by buying a monovarietal or monocultivar, which means the oil is produced with one type of olive. It’s not entirely better, but you’re able to learn about different olives and their unique attributes.