What makes the best olive oil?

• A conversation with Floris
• The different grades of olive oil
• The quick testing method: acidity level
• Determining the best olive oil organoleptically
• What influences the quality of olive oil – molecular structure?
  • Location of the olive trees
  • Which plants, animals and insects live around the olive trees?
  • Are the trees or olives damaged by animals?
  • Is manure / fertilizer / pesticide used?
  • When in the year are the olives harvested?
  • Under what temperatures are the olives harvested?
  • How are the olives harvested?
  • How are the olives transported after harvest?
  • How quickly are the olives pressed after harvest?
  • How is the olive oil pressed?
  • The age of the olive oil
• What is the best olive oil?

Did you know that the olive oil market is currently under significant pressure? In Spain and Italy—countries that traditionally accounted for nearly 70% of global olive oil production—there have been major shortages for two years in a row. And this year, that situation is very unlikely to improve. Combined with prices that are already on the rise, olive oil is becoming significantly more expensive—we’re feeling the effects firsthand. All the more reason to make sure you’re getting what you pay for. If you’re looking for top-quality extra virgin olive oil, it’s helpful to know how to recognize the best.

For this, we’re speaking with one of the founders of Gkazas Olive Oil, Floris. After years of exploring what defines a high-quality extra virgin olive oil, he now shares his insights with us. “I don’t mind whether people buy beautiful olive oil from us or from someone else. What matters is that you buy the best olive oil from someone who is passionate about the craft, who is transparent about the entire production process, and whom you trust. My mission is to make high-quality olive oil accessible to as many people as possible.” So, what exactly is high-quality olive oil? Let’s start with a brief explanation of olive oil itself.

There are six types of olive oil suitable for consumption (and another four types that aren’t!). In short, here’s what they are. You can find a full article on the different types of olive oil here!

1. Organic extra virgin olive oil is the best and most expensive form of extra virgin olive oil. No pesticides are used, and chemical tests will show none in the final product.
2. Extra virgin olive oil is from the first pressing (without heating) using mechanical presses. It has a low acidity (maximum 0.8%) and retains most of its nutrients, such as vitamins, minerals, polyphenols, and antioxidants.
3. Virgin olive oil has a higher acidity (up to 2%) and is usually lower in taste, color, and aroma compared to extra virgin olive oil.
4. Olive oil is often a blend of (extra) virgin olive oil with refined olive oil. It’s suitable for cooking but contains little flavor or nutritional value.
5. Refined olive oil is low-quality oil that has had impurities removed, usually through chemical processing. It’s blended with first-press olive oils to make it palatable and edible.
6. Pomace olive oil is made from the leftover olive pulp after pressing extra virgin olive oil. We extract oil from it naturally and add extra virgin olive oil for improved taste and nutritional value. Learn more about what pomace olive oil is here.

What’s the best type of olive oil? After this little refresher, you probably know: organic, extra virgin olive oil that scores highly on organoleptic testing. Now let’s speed ahead to what actually makes an olive oil the best. We’ll start with ways to test the qualities mentioned above. The first method? Checking the acidity level:

 

You can test the acidity of olive oil right after pressing. According to this method, olive oil is considered high quality (i.e., extra virgin) when its acidity does not exceed 0.8%. For the best olive oil, the acidity is below 0.5%. While this is a valid way to classify different types of olive oil, it’s not the best method for determining which one is actually the best. Floris explains: “Using acidity to determine olive oil quality doesn’t necessarily say anything about its taste or defects (more on that in a moment). So it’s possible for olive oil to be classified as extra virgin based on acidity, but not pass as extra virgin in organoleptic testing (see the next section).”

 

Did you know… the percentage of olive oil with an acidity below 0.8% (and thus classified as extra virgin by this measure) is relatively low per country? In Italy it’s 30%, in Spain 35%, in Greece 80%, and on Crete 90%. Globally, this figure is just 10%. However, if you look at the percentage of olive oil from Crete that qualifies as extra virgin based on organoleptic criteria (see below), only 40% is of the highest quality, meaning truly extra virgin!

Organi-what? Organoleptic! This is a better and more reliable way to determine whether you’ve got the best olive oil in your hands… Floris explains: “It means determining the quality of olive oil based on taste. You conduct a sensory analysis (some experts can detect this by tasting, and it can also be done in a lab) where you look for positive traits (attributes) and negative traits (defects). A truly high-quality olive oil can reveal up to 25 different flavor notes, such as nuts, tomato, and artichoke. This, of course, all depends on the tree’s location, the type of soil, and so on. There are three main parameters: fruitiness, bitterness, and the peppery sensation in the throat. The higher these values, the higher the quality of the olive oil.”

 

Defects in olive oil can present themselves in various ways and are recognizable to trained tasters. The oil might, for example, taste musty or rancid. You can also spot it by looking at the color (anything outside the range of deep green to golden), or if mold is present in the oil.

“This is about the effect on the integrity of the molecular structure throughout the life cycle of the olives, and ultimately on the olive oil itself. And let me prepare you—there are quite a few influencing factors. That’s why the best olive oil doesn’t just happen. It’s a constant process of love, care, analysis, improvement, and a bit of luck!”

 

If you really want to understand the reasons behind the differences in olive oil quality, take a moment to sit down. Here they come. This, by the way, is the essence of what makes the best olive oil!

Of course, the environment matters. The most important factor is the climate. A mild Mediterranean coastal climate is ideal. You need not too much, but also not too little rainfall. It shouldn’t be too hot, but also not too cold. And while too much wind is undesirable, a gentle breeze is beneficial.

 

In addition, the trees should get water from natural rainfall. Is that sufficient, or does extra watering need to be done? Extra water is superficial, meaning the olive trees don’t have to work as hard to get what they need. As a result, the trees become less resilient—and you can actually taste that in the final harvest. It also helps when the trees are spaced far enough apart to ensure they get enough room, water, and sunlight to thrive.

A variety of plants, animals, and insects (also known as polyculture) leads to richer soil, better nutrition, and therefore healthier olive trees and high-quality olives (source). One way to measure this is through Demeter, which assesses the right soil biodiversity. For example, the goal is to find at least one earthworm every few square centimeters.

Free-roaming goats and sheep can be very beneficial for the soil, as their manure serves as a natural fertilizer. However, they can also nibble on the leaves and olives. The biggest threat, however, is the olive fruit fly (Dacus oleae), a type of pest that burrows into the olives and feeds on them. This can be devastating for the harvest!

What is the best olive oil? As just mentioned, it’s ideal when the trees are naturally fertilized by free-roaming sheep and goats. This is the most beautiful approach (there’s also a strong sustainability argument—see the section ‘Sustainability Aspects’—linked to the best olive oil), because it reflects how nature intended and, most importantly, it’s better for the soil than using artificial fertilizers is. Producing artificial fertilizer, for instance, requires energy and naturally contains a lot of salt. And that’s not even mentioning pesticides—and how harmful they are for biodiversity and for your health…

The timing of the harvest influences the quality of the oil. An early harvest generally means smaller olives. This results in a more concentrated olive oil, meaning the oil comes from less fruit flesh. As a result, it often has a more intense flavor and relatively higher nutritional value. This has a positive effect on the quality of the olive oil—assuming, of course, that all other variables are also favorable.

Olives are usually harvested in the autumn or winter. Harvesting at lower temperatures is better, which is why it often takes place at night or very early in the morning.

There are three ways to harvest olives. Traditionally, everyone used wooden sticks to tap the olives from the tree. This method causes the least harm to the tree (read: damage), but it is very labor-intensive and time-consuming. That’s why most people now use electric sticks that rotate. This method is slightly less gentle on the tree (as it can cause some damage) and it requires energy.

 

However, there are now also large machines that shake the olives from the tree. These machines use a lot of energy and cause significant damage to the trees.

It’s important to transport olives in the best possible way. The less pressure and the more air circulation the olives have during transport, the less damage they sustain. This means their molecular structure remains intact, which helps preserve the quality.

 

The best method of transport is in crates. These offer the best protection by absorbing shocks during transport. Loose in trucks also works well, as the olives are packed tightly together and can absorb impacts that way. Jute sacks are also commonly used—they offer slightly less protection than crates but are still a very good alternative. Plastic bags, however, are not ideal, as olives tend to ferment more quickly in them.

Olives begin to ferment as soon as they are detached from the tree, and fermentation is not beneficial to the quality. So, the faster they are pressed, the better! The general rule is to press within 24 hours after harvesting, but the best producers head straight to the press the very same day. This is absolutely essential when it comes to producing the best olive oil.

There are several methods of pressing olives, with the oldest being the stone press powered by horses or donkeys. There’s also the vertical press using mats and the hydraulic press that presses down with force. However, the most modern method—where the olive oil comes into minimal or no contact with oxygen—is considered the best. Here’s how it works:

1. The olive flesh is separated from the pit using a rotating grater.
2. The flesh is transferred into a large container where it is mixed with water for about two hours, allowing the olive oil to be released from the pulp.
3. The olive oil is separated from the water.
4. The olive oil is first coarsely, then finely filtered.
5. The oil is stored in large tanks without any exposure to oxygen.
6. It then goes through a self-filtration process for three months, during which sediment settles at the bottom, and the clear olive oil is ready to be bottled or canned.

The Greek (and by now, we and everyone who has been with us for years) prefers to enjoy olive oil straight from the press! This bright green olive oil is bottled immediately and used with bread, on salads, and in dishes. It doesn’t get any tastier than that!

 

Floris: “You can definitely store olive oil for quite a long time. There are even stories that amphorae of 2,000-year-old olive oil were found at Knossos—and still edible! However, when it comes to flavor, it’s best to store olive oil as briefly as possible. The general rule: the younger the olive oil, the more powerful its taste. Again, we’re talking about the key characteristics—fruitiness, bitterness, and that peppery kick in the throat. There’s also a lower chance of defects when the oil is consumed sooner.”

Oxidation is a lurking enemy. Fortunately, you don’t need to worry about it if you use olive oil like the Greeks do. On average, they consume 27 liters per person per year. Not only is this incredibly healthy, but an opened 5-liter tin of extra virgin olive oil of high quality will stay flavorful for up to a year under the right conditions.

 

Can’t finish a tin of olive oil within 12 months? Then make sure to pour it into smaller bottles to minimize exposure to oxygen. Check out these tips on how to store olive oil properly, so your oil remains the best it can be for as long as possible. It’s also essential that the olive oil is packaged in a dark bottle or tin.

What is the best olive oil? It’s a lot to take in—all the factors that influence what makes a good olive oil. It might still feel a bit overwhelming, but hopefully, things have become a little clearer too. The essence of the best olive oil lies in knowing exactly where it comes from. That’s because you trust the person or brand behind it—because they transparently do everything they can to offer you the highest quality possible at a fair price. It all comes down to taste (both positive attributes and potential defects), not just the numbers or appearances.

 

And once you have that best olive oil in your kitchen, let it flow generously—and of course, store it properly so it stays delicious for as long as possible. Got it? 🙂 Then go ahead and grab yourself a 5-liter tin of olive oil!