Olive oil is a nutritionally valuable food that has been vital in our diet since ancient times. Also referred to as “liquid gold”, it is not surprising that its price on the market is reaching new heights by the day.
That is also why, together with honey, it is the most counterfeit food item nowadays!

So, what do we know about olive oil, its quality, nutritional value and how it can be enjoyed?

Where is the olive tree from?

Olive oil is found in the form of tiny drops inside the olive fruit (mostly vacuoles) growing on the olive tree (Olea europaea L.).

You wouldn’t believe how old the olive tree really is. It is one of the oldest cultivated trees in the world, dating back 5,000 years. Today, there are more than 800 million olive trees worldwide.

According to one theory, it originated in ancient Persia and Mesopotamia, while others believe it came from Africa.

Thanks to the Phoenicians, it spread through the western regions of the Mediterranean basin and has established itself as a staple food ever since.

Today, olives are grown all over the world, but 90% of them are spread out through the Mediterranean. Spain, Italy and Greece are the top-ranked ones on the list.

Are there different types of olive trees?

According to the International Olive Council (IOC), there are 139 olive varieties called cultivars. Each of these will give an olive oil with specific chemical characteristics that will have a special appearance, taste and smell.

Unfortunately, that is not the only factor involved. Depending on the growing region, harvesting and processing methods, each of these varieties will give specific results, with characteristics that are miles away from each other.

Some widely spread varieties used in olive oil production are:

• Picual, Arbequina, Hojiblanca (Spain)
• Leccino, Frantoio (Italy)
• Coratina, Kalamata, Koroneiki (Greece)
• Cobrançosa (Portugal)
• Oblica, Istarska bjelica, Buža (autochthonous Croatian varieties)

Varieties like Kalamata, which you’ve probably heard of, are also cultivated for producing table olives). Still, some of these cultivars are grown explicitly for oil production.

Monovarietal vs. blend

If the olive oil is made from a single variety, it will be called monovarietal or monocultivar.

But you will also often encounter different blends obtained by mixing two or more varieties.

Traditionally, olive oil was produced by cooperatives. Local farmers took their olives to the joint mill, which resulted in a blend of different varieties. Later It would have been sold through a cooperative.

A similar system is still very much present in Croatia. The only difference is that the cooperative model was largely abandoned, creating a lot of small producers. They take their olives to the closest mill but sell the oil individually. As a small individual producer, you don’t have much control over the production process since you can’t be present in the mill, which can jeopardise your product.

Bigger individual producers are emerging over the years with their own mills on their private farms. They can much better influence the production process and what appears is a more extensive selection of products, ranging from monovarietal oils to different blends with desired characteristics.

Compared to monovarietal oils, blends will influence olive oil composition. Still, both of these types can be high-quality oils.

How is olive oil made?

Harvest

Olives are harvested from as soon as the end of August to as late as December. The optimal harvest time depends on the growing region, the variety of olives and the desired ripeness.

Traditionally, olives are hand-picked from the tree, which is still a common harvesting method nowadays. Hand-picking is definitely the slowest and most expensive method but also the best one, thanks to the fact that it helps preserve the quality of the olives and is by far the least invasive method for the trees.

Usually, bigger operations use machinery like a long-handled vibrating tong or tractors with shakers attached to them. These methods are much more aggressive than hand picking and can damage the fruit, putting the oil’s quality at risk.

Ideally, you want to process olives as soon as possible after the harvest to get the best quality oil.
After being picked, olives must be washed to remove all the leaves and dirt. All these leftover leaves can give an unwanted bitter taste to the olive oil.

Fruit crushing

Next, olives are crushed to release oil from the vacuoles by tearing their flesh. Since prolonged crushing time may deteriorate the sensory characteristics, it is recommended to crush it for 20-30 minutes. Granite stone mills, specific for traditional systems, are being replaced by better-performing metallic crushers.

Extraction

In this step, with the addition of water, the obtained olive paste will be separated into oil, wastewater and wet pomace. The challenge is to use as little additional water as possible and extract as many antioxidant compounds as possible together with the oil. New technologies are making the extraction much more efficient, producing higher-quality olive oil.

Reading about how olive oil gets processed, you would think its production is completely clean and sustainable. But there is one considerable downside to it: a byproduct called olive mill wastewater (OMW), which is far from environmentally friendly. In large amounts, it pollutes natural waters and threatens aquatic life. Much research is being done on potential treatments of this byproduct, which are still pretty expensive for the large number of small mills spread out through the Mediterranean.

Quality categories of olive oil

Why are some oils called extra virgin, virgin or simply olive oil? Why should we care?

According to the International Olive oil council (IOC), olive oils are separated into six main categories depending on the degree of modification during the production process, their resulting organoleptic properties and quality.

Under the “Virgin Olive Oil category”, we can find extra virgin olive oil (EVOO), virgin olive oil (VOO) and lampante.

EVOO is considered the highest quality olive oil, followed by VOO.

They are obtained using only mechanical or physical processes under the right temperature conditions to not cause any changes to the oil’s chemical structure.

Lampante is the lowest quality oil that is not used for human consumption because of its unacceptably high amount of free fatty acids.

On the other hand, refined or simply olive oil are the names for oils that have been further refined or mixed with other lower-quality oils. They are less nutritious than virgin ones, especially regarding the amount of beneficial phenolic compounds with antioxidant and anti-inflammatory potential.

Nutritional value of virgin olive oils

Olive oil is rich in unsaturated fatty acids, the most important ones being oleic acid and linoleic acid (an essential omega-6 fatty acid).

Compared with diets high in saturated fat and cholesterol, diets high in unsaturated fatty acids show a protective effect on risk markers for cardiovascular diseases.

Extra virgin olive oil’s distinctive colour, smell and taste come from various molecules like vitamins, phenols, phytosterols (β-sitosterol), pigments and hydrocarbons like squalene.

Oleuropein, a phenol type, has shown to be effective against inflammation, microbes and cancer.

Phytosterols are plant steroid compounds with a very similar chemical structure to cholesterol. They have shown total and “bad” LDL-cholesterol lowering abilities.

Tocopherols and carotenoids are pigments that show great antioxidant potential but are sensitive to higher temperatures (frying) and start decreasing after longer storage.

Factors influencing the composition:

• olive variety
• growing area/ altitude
• type of soil
• growing conditions
• tree age
• treatments of olive trees
• harvest

Is olive oil gluten-free?

Olive oil naturally doesn’t contain gluten, but labelling it as such is against the law.

Can you cook with EVOO & VOO?

Because of its high percentage of unsaturated fats, which oxidises more easily, you would expect that virgin olive oils are unstable during the cooking process. But due to its good balance in poly (PUFA) and monounsaturated fatty acids (MUFA), it has shown to be very good for various cooking methods, including frying.

I would encourage you to use virgin olive oils in your everyday cooking, especially in their raw state. Enjoy it but with moderation on your mind!

Does olive oil go bad?

When your olive oil has gone bad, it starts smelling sour or bitter. That would be a cue that it has gone rancid. When oil goes rancid, it means that the fatty acids within it have oxidised due to the presence of oxygen.

The shelf life of extra virgin and virgin olive oil is between 9-18 months, depending on the oil’s initial qualities and the storage conditions.

When storing olive oil, your biggest enemies are light and temperature. Olive oil degrades faster when exposed to sunlight, losing many beneficial properties. I recommend keeping it in a dark glass container rather than transparent glass or plastic.

The ideal temperature conditions for keeping olive oil is around 23 ºC. Keeping it beside your stove where the temperature fluctuates is not the best option.

Also, buy smaller packages of EVOO or VOO that you will use soon after opening! This way, you will ensure that it keeps most of its properties before you have finished the bottle.

Never keep olive oil in the refrigerator, as fatty acids will break down.

So, to recap:

• Dark container
• Temperature around 23 ºC
• Smaller packaging