Introduction
Every year for the past 13 years of living here in Portugal, a local team of olive pickers has come and harvested the olives from many of our trees and taken them to the local olive mill. In exchange we receive enough olive oil for our own needs, and sometimes enough for some gifts.
However, we have hundreds of mature olive trees, and we are not harvesting as much as we could. Although we cannot compete with large-scale farms in the production of a commercial olive oil, I realised that if we could produce a premium olive oil with high-nutrition content and delicious flavour, then it could be a good economic activity for us, particularly as we wait for our fruit and nut trees to mature.
At the same time I discovered that the extra virgin olive oil produced at the large local olive mills is questionable in its quality due to the processing methods and not at the standard that I would like to consume myself.
I did a deep dive into the world of small-scale olive oil production, which in contrast to the industrially produced oil on the supermarket shelves, is an art.
Last September (2025) we ran some tests making early-harvest olive oil using a privately owned small olive mill. I sent some to a lab to be tested to see if the oil meets the required standards to qualify as a premium oil. I wanted to find out if making olive oil is something I want to spend time doing and if it is worth investing in the infrastructure for making it.
Producing olive oil on a small scale on the farm has many benefits that combine to create a high-quality cold-pressed EVOO with superior health benefits.
- Harvesting can be done by hand in small amounts.
- Processing can be done within hours of harvesting.
- The temperature can be controlled and kept below 27 degrees.
- You can guarantee that your equipment is kept clean to reduce chances of contamination.
- Oil can be immediately collected in opaque stainless steel containers and stored in a cool place before bottling as needed. This reduces the risk of oxidation.
- The waste products from the oil can be put to good use or returned to the trees as fertiliser.
Production Methods
Most olive oil production these days is done on large-scale monocultures, even if organic. Small producers cannot reduce costs to compete with such a mechanised farming model, so they have to focus instead on superior quality oil for discerning consumers who value hand-harvested, gourmet extra virgin olive oil. High-end restaurants and top chefs also like to use gourmet olive oil.
There are many factors that affect the levels of polyphenols and other healthy compounds in EVOO. These include:
- Olive variety.
- Soil type and health, and other environmental factors.
- Harvest time.
- Agricultural methods (e.g., pruning, irrigation, fertilisation, distance between trees, use of ploughing in the grove).
- Harvesting methods.
- Processing methods.
- Storage conditions and exposure to light and heat from harvest to final container.
All of these need to be addressed to create a premium quality oil.
Polyphenol compounds have been shown to increase relative to diverse and healthy soil biology, so regenerative farming is highly suited to premium olive oil production, as well as having added benefits such as protecting biodiversity and locking in carbon. The market for high-polyphenol EVOO promotes traditional low-impact farming methods and allows those farmers to receive higher prices for their olives. Ancient olive groves that were virtually abandoned for economic reasons (inability to compete with large mechanised farms) are being brought back into production.
Stages of production
1. Harvesting
To prevent damage to the olives and subsequent oxidation, hand harvesting without mechanical aids is best.
2. Cleaning, Washing and Sorting
Leaves are blown off and olives are washed. Any olives that are damaged or eaten by bugs are discarded.
3. Grinding
Traditionally done with a stone mill, the olives and seeds are crushed and ground into a thick paste in a slow and gentle way. Today hammer mills are more common, which use spinning metal blades to pulverise the olives at high speed, a more aggressive, quick and intense process which can lose some of the subtlety of flavour but can also help release more of the pungent flavours.
4. Malaxation
For 30-40 minutes the olive paste is churned so that the oil droplets start to clump together, making it easier to separate the oil in the extraction phase. For the oil to be designated ‘cold-pressed’, it needs to stay below 27 degrees Celsius.
5. Extraction
The oil is separated from the solids – called pomace. This is done in a hydraulic press or with a centrifugal system. Centrifugal systems are more common these days, as they are easier to keep clean and expose the oil to less oxygen.
6. Dealing with the waste pomace
The woody matter is separated from the pulp – the wood can be used for biomass, the pulp for biogas.
The waste can also be returned to the olive trees together with chipped prunings to fertilise.
7. Filtration
Filtration through a cotton filter is an optional step, but it helps to remove more sediment to make a clear oil. Filtered oil has a longer shelf life, as the leftover particles can cause fermentation and spoiling over time.
Unfiltered oil is often prized for its artisanal, robust and rustic flavour but needs to be consumed within a few months.
8. Storage and Bottling
Oil is collected in airtight tanks, ideally made of stainless steel, and stored in a cool, dark place to settle. This can be for a few weeks or even a few months before it is bottled. Some producers pump nitrogen into the top of the tanks to remove any oxygen and prevent oxidation.
The oil is then bottled, ideally in opaque glass or ceramic bottles.
Our 2025 Harvest
2025 was a very abundant year for olives. The trees were fully loaded. For this first experiment with early-harvest olive oil, we formed a team and harvested over two days in two different locations. I waited until the hard green olives could produce a little oily white liquid when squeezed hard. We made the first harvest on 9th October.
Olive harvesting is traditionally a time when family and community come together to work. Some climb the tree to harvest from the top or to cut some branches to the ground, where children and smaller people can strip them with special little rakes. The olives are collected on a big sheet on the ground and then gathered to be sorted, rejecting as much as possible the damaged ones which will oxidise and go rancid more quickly.
We started early and finished by a late lunchtime in order to take the olives to the lagar for pressing.
There were some issues with the olive pressing machine that made it hard to keep the temperature low, especially during a hot afternoon. However, it still remained below the 27 degrees Celsius for extra virgin oil.
It is a special moment when the malaxated olives start being pressed and the first drops of oil come out. It tasted really good.
I had the oil picked up by a courier and taken to a lab just across the border in Spain that offered a wide range of tests and was recognised by the international olive oil organisations.
The results showed a well-balanced oil with very low acidity (0.14). Its throat burn demonstrated decent levels of oleocanthal, but the reading for hydroxytyrosol came as 0. I am not sure why; maybe the oil got too hot in processing or during transport to the lab.
This year I will harvest earlier, from more trees, and see how the tests come out. I also want to harvest some wild olives and mix them with the cultivated ones. Wild olives are small and produce less oil but are known to be very rich in nutrition and flavour.
What makes olive oil ‘extra virgin’?
Determined by the International Olive Council, virgin olive oil must meet these requirements:
“Virgin olive oils are the oils obtained from the fruit of the olive tree (Olea europaea L.) solely by mechanical or other physical means under conditions, particularly thermal conditions, that do not lead to alterations in the oil and which have not undergone any treatment other than washing, decantation, centrifugation and filtration.”1
Extra Virgin Olive Oil must also have
- a free acidity of less than 0.8 g/100 g, expressed as oleic acid. (Premium oils are expected to have a free acidity of less than 0.3 g/100 g.)
Free acidity is the amount of acids that are free to react with other substances; a high level of free acidity in olive oil denotes that more of the bonds between triglyceride molecules have broken down due to oxidation. Higher quality oils will have lower free acidity due to factors such as the freshness of the olives when they are processed, low temperatures during processing, and higher levels of antioxidant compounds in the oil. - Low peroxide value. This refers to the level of oxidation present in the oil.
- Needs to meet a variety of other quality criteria regarding taste and purity.
Oils are given a sensory evaluation of the taste and feel in the mouth. EVOOs are expected to have a fruitiness, and high polyphenols are denoted by a peppery flavour.
Health Benefits of EVOO
For millennia olives and olive oil have been recognised and studied for their health-giving properties, and the first scientific study was done in the 1950s. In recent years the interest in high quality EVOO as a functional health food, or even as a health supplement, has grown.
Olive oil has been studied extensively for its health benefits, not only as a healthy fat high in monounsaturated fatty acids (MUFA) but also for its high levels of certain polyphenols, sterols, tocopherols, and carbohydrates such as squalene. Here are some of the specific benefits that studies on these compounds have revealed:
Hydroxytyrosol – a strong antioxidant with cardioprotective properties
Oleocanthal – Discovered in 1993, this compound is anti-inflammatory, antioxidant, and anti-tumour. Its anti-inflammatory action makes it an alternative to medicines such as ibuprofen.
It is oleocanthal that creates the ‘throat burn’ in fresh high quality EVOO; interestingly, liquid ibuprofen also has this same effect. Found only in extra virgin olive oil, oleocanthal is not even present in olive fruits or leaves. It is created during the mixing or malaxation process which separates the oil from the olive paste.
Squalene – a tumour inhibitor, UV protective for the skin, used in many skincare products.
Oleuropein – cancer cell inhibitor
Oleic Acid – the main Monounsaturated Fatty Acid in Olive Oil – is anti-inflammatory and helps maintain HDL (high-density lipoprotein) levels, which tend to reduce with age
Summary of the most studied Health Benefits of Olive Oil
Health Benefits of Olive Oil https://pmc.ncbi.nlm.nih.gov/articles/PMC7466243/
Cardioprotective
Studies have led to the conclusion that the consumption of olive oil as the main fat source is the major factor in the low incidence of cardiovascular disease in countries eating a Mediterranean diet.
For example: “As far as the biological activities of olive oil are concerned, a review by Covas et al. [36] examined 15 human studies and the majority indicate that olive oil (rich in phenols) is superior to seed oils and olive oil with low phenol content. This superiority was attributed to the reduction of CV risk factors, such as reduced plasma LDL, improved endothelial function and a decreased prothrombotic environment. 2
The cardioprotective action of olive oil is due to various actions – reduction of LDL (low-density lipoprotein) cholesterol levels, improvement of endothelial function (the lining of the blood vessels), and helping to prevent blood clotting.
Anti-inflammatory – Oleic acid, the MUFA that is dominant in olive oil, has anti-inflammatory properties, as does the polyphenol oleocanthal.
Anti-oxidant – protects against oxidation of blood lipids such as LDL
Gut microbiota modulation – EVOO rich in phenolic compounds supports the growth of good bacteria, such as bifidobacteria. It also has an anti-pathogenic action against pathogenic bacteria such as E. coli and H.pylori.
Anti-cancer – Oleocanthal in EVOO has shown to be protective against cancer and was shown to induce cancer cell death.3 EVOO has been shown to be particularly protective against breast cancer.4
Antimicrobial – Oleuropein, hydroxytyrosol and tyrosol have antimicrobial properties and can be effective against pathogenic bacteria.
Neuroprotective – one study showed that half a teaspoon a day of olive oil led to 30% risk reduction of dementia-related death. The polyphenol Oleocanthal was shown to reduce plaques in the brains of mice, and showed promising results on alzheimer’s patients in a human trial
Anti-diabetic (Type 2) – Two tablespoons a day of OO had a positive effect on fasting glucose and insulin levels.
Metabolic health – Some evidence is showing OO prevents long-term weight changes (for people who lose weight, it helps them to stay at that weight).
European Health Claim
In 2012 the European Food Standards Agency approved a health claim for EVOO – ‘olive oil polyphenols contribute to the protection of blood lipids from oxidative stress’ 5. It can only be used for olive oils that contain at least “5 mg of hydroxytyrosol and its derivatives (e.g., oleuropein complex and tyrosol) per 20 g of olive oil”. An increase in HDL cholesterol was shown to correspond with the levels of these phenolic compounds and their derivatives.
The word ‘derivatives’ is used, as during the process of making olive oil, the malaxation or mixing process creates enzymatic reactions, by which hydroxytyrosol converts into other powerfully healing compounds such as oleocanthal and tyrosol. This is the alchemical aspect of making olive oil.
The benefit for producers of top-quality EVOO is that this claim can be made on the bottle, distinguishing it from the general term ‘extra virgin olive oil’, which covers a big range of qualities.
More research needs to be done to explore the complexities of the different compounds in EVOO, the benefits of each specific polyphenol, the possible synergies between them and their bioavailability in humans. Although there are numerous studies showing benefits, many studies up to date have been with short-term small trials and have proved inconclusive as regards making official health claims.
Challenges in developing a successful olive oil business
Here we have plenty of challenges as we plan for future harvests:
1. We do not know the variety of olives, as they have been here much longer than us. We may need to graft other varieties to be successful in increasing the polyphenol levels.
2. The land is mostly steep hills, and the trees are quite spread out in different clusters or rows in the water lines and valleys between the hills.
3. So far we have not offered any soil improvement techniques around the trees (such as inoculation with beneficial microbes); however, it is possible that in some areas we already have a supportive soil biology for the trees, and we can propagate these microbes to give to the trees in areas that are more poor and degraded.
4. We intend to harvest early, in late September when temperatures can still be in the 30s. So keeping the olives cool during transportation and processing is not easy.
I do not expect to be able to match the level of quality as some of the top high-polyphenol olive oils and realise that it takes time and investment in each step of the process, but if we can reach the EFSA-required levels for using the EU health claim on our products, it will already mean that we could sell into the growing market for premium olive oil. Even with challenging terrain, we could make a decent return to support the work of regenerating the land.
If that does not work out, we can at least produce a small amount of high-quality oil each year for our own use and the use of those who come and stay with us and sell the surplus in local markets, as I have done this year.
We can also experiment with making a special health oil by adding herbs to the bottles, such as wild oregano flowering tops, to add even more beneficial health compounds and antioxidant properties.
I have immense love and respect for the olive tree. It is so resilient and powerful, as well as offering an abundance of nutrition and healing properties from its fruits and its leaves. I hope to honour this tree with careful harvesting and pruning and by sharing its bounty with those who can benefit from it.
Footnotes