Making your own olive oil

Where I live there are about 100 “productive” olive trees. In 2021, we decided to go through the experience of producing our own olive oil from them and I want to share the process and my key learnings with you, because there are many things that I personally did not know and that I believe will be helpful for you at the moment of choosing which olive oil to buy.

1. Picking the olives

Olive season starts beginning of October and lasts until December more or less. It really makes a huge difference when you pick the olives. When the olives are still young and green, they are highest in antioxidants – the oil you get from those olives will be very green in color and is actually called “olive juice” because of its freshness and high quality. Its taste will be rather spicy and people usually only use it for raw preparations, not for cooking. However, this is also when the oil content of the olives is still rather low, so you will only obtain about 7-8% of olive oil from them at the first cold pressing. That means 700-800ml of oil for each 10 kg of olives, so a rather low productivity.

These young green olives are also the ones used for making cured olives because of their firmness. In fact, many people who have small olive yards pick their olives very early to sell them to industrial cooperatives (where I live they get paid only 40-60 cents per kg of olives!) who then process and sell them (much more expensive) under their brand name. So just because the olives are not organically certified, does not necessarily mean they are not, at least in their original, unprocessed state (read on to know the different ways olives can be processed).

If you let the olives ripen, they change in color and become purple. At this stage you will get more oil from them (10-12%) but the oil is of a somewhat lower quality as olives might already have been contaminated with worms or started to ferment, and acidity will be higher (even though the taste is often softer). Some (usually industrial) producers might take their olives through a second round of pressing (and in some cases even chemicals are applied) to get out even more oil. The ripe olives no longer serve for curing (only for salt-drying) as they spoil much quicker.

Olives can be picked in a variety of ways. The most common ones are:

  1. By hand: This is only an option for relatively low-hanging olives. People who take good care of their olive yards actually try to prune the trees in a way that they do not grow too high and it is easy to pick the olives. Many people here in rural areas make deals: they cede their olive yard to people in exchange for a part of the harvest. Others hire people to pick the olives for them (paying them the above-mentioned cents per kg).
  2. With the help of a stick and a net: hitting the olives off the tree so that they fall down onto a net that you previously extended under the tree.
  3. With a tractor that shakes and vibrates the tree so the olives fall off onto a net extended under the tree. This is a rather invasive and violent way, however, much more efficient and especially interesting for bigger producers who have this kind of machinery.
  4. If you wait long enough, they start falling off the tree by themselves, however, as mentioned above, the quality will be much lower.

2. Processing the olives

After picking the olives, you have the choice to either sell them, cure them yourself (this is usually only an option for small quantities) or make oil from them.

  1. Making oil

Once you picked your olives, you store them in special boxes and you then need to transport everything to an almazara (a mill where they press your olives into oil). Normally you need at least 700-1.000kg for an almazara to make your oil (otherwise you might just get some oil but not necessarily yours, which can be an issue if the almazara accepts both ecological and non-ecological olives). Often people who harvest a lot press in several lots, as you cannot keep the olives for more than a few days (some try to press them in the same day they pick them to optimize quality). In our case, we hand-picked only about 385kg of young olives in 5 days in early October. This is not a lot. However, we found a small, ecological place and they accepted to press our olives at the same price of the full load (which made it relatively 2x as expensive for us, because we paid 91 Euro for milling 385kg instead of 700kg – to that you have to add the price of the gas to drive there and back and the cost of the glass bottles, see below). The result was 30 liters of very green and very tasty “olive juice” for a cost of about 120 Euro, or 4 Euro per liter (not counting the work!).

The only downside was that there was no choice when it comes to packaging – per default they put your precious oil in cheap plastic bottles… at least in the region where I live that is the common practice. It is then up to you to rebottle if you prefer something else. Of course, I did not want my high-quality oil to get contaminated with toxic endocrine disruptors, so immediately after having picked up the oil (and knowing how many liters had come out), I went to buy green glass bottles and re-bottled the oil. Not many people here proceed that way, but some do. They might have a stainless-steel container where they keep all their oil and rebottle from there… I guess there are producers (especially bigger companies) who get their oil directly filled into bottles but the regular consumer does not (at least not where I live). Which actually made me wonder if the oil you buy in dark glass bottles in the store has not actually been stored in plastic before…

b. Curing olives

I also experimented with curing olives in a variety of ways. You can use only salt (plus herbs/spices) or more harsh chemicals (caustic soda, also used for soap making) to get rid of the bitter taste olives have (which is why you cannot eat them straight from the tree!). I used salt-curing and experimented with different percentages: from 10% (very high but “saver” in terms of spoiling) to 8% (the generally recommended percentage) to as low as 5% (which is more like lacto-fermenting and keeps many bacteria alive, making the olives a “probiotic” food). I tried washing them (for weeks/months) before putting them into the salt-water, with cuts (for faster curing in only 2 weeks) and in their whole state. And I also tried salt-drying. My favorite method is putting them into a 5-8% salt mixture in their whole state, without prior washing and forgetting about them for a year. These were still fine to eat after now 2 seasons, keeping their firmness and taste, while using other methods they spoiled sooner, becoming all mushy or developing mold on top (which to some extent is normal and not harmful). Industrial curing might include chemicals, taste enhancers, preservatives and colorants to make them last longer, taste “better” (be addictive) and avoid the mold.

c. Taking care of the trees

Once the harvest is over and the oil is pressed (or the olives are sold or cured), the process is not finished. The trees need to be pruned, at least if you wish to balance “giving and receiving”. Well-pruned trees give olives in a more balanced way, whereas neglected trees will usually produce fruit every second year only. Pruning the trees means to cut of dry or dead branches, branches that are growing too high or too vertical or overlapping with other branches. You also need to get rid of the “chupones”, the “babies” growing at the foot of each tree and also on the stems (which would develop into new branches/trees if you let them). All of this is a whole lot of work, especially as, after pruning, you also need to get rid of all the biomass, usually by burning it (bigger branches serve as excellent firewood for your chimney, the small stuff gets burned in situ).

Going through the experience and knowing all the time, energy and costs involved, I personally decided that it’s much easier and more economic for me to simply buy my oil from some local producers rather than doing all the work myself for the few liters I consume each year. And this is true for most of the foods: producing them yourself is A LOT more expensive after all than simply buying it… which kind of shows again how undervalued farm-work and our food is, including – and especially – the “organic” food.


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