After reading through this blog, you consider yourself a smarter olive oil purchaser. You don’t just blindly buy any ol’ bottle of olive oil anymore, but your curiosity has gone further still. Now you wonder what’s really in that bottle. Also, which steps are involved in the olive oil manufacturing process?
To make olive oil, food manufacturers will do the following:
- Harvest whole olives
- Clean and wash them
- Take off twigs, leaves, and stems
- Grind them down
- Malax or mix them
- Isolate all the parts, including solids and vegetable water from the oil itself
- Do extra processing, put in additives, or even remove the pits if necessary
If the above steps have piqued your interest and now you want to know more, you’ve come to the right place. In this article, we’ll cover the steps of producing olive oil in much more depth. By the time you’re done reading, you’ll know and appreciate the humble olive’s journey to end up in your bottle of oil.
How Olive Oil Is Made Step by Step
Step #1: Harvesting the Olives
Before olives can become oil, food manufacturers need to harvest the fruit itself (and yes, olives are a fruit since they grow on trees).
There’s a certain period to claim the most bountiful fruit harvests from olive trees. This is the end of August until November. That said, if you want olives at different levels of ripeness, the period can vary. That’s also true depending on the variety of olives and their region.
For making olives into oil, they should be at a certain ripeness. The ideal olive should have a pale yellow skin. Harvesting them now would be early in their ripening process. A typical olive will have a green color. Then it becomes pinkish-red and could even turn black. This doesn’t necessarily mean the olive is bad, just that the person harvesting it waited until it was completely ripened. The flavor changes with the color of the olive. It’s more bitter towards the beginning of the growth cycle and then becomes mellower.
You can harvest olives either by machine or by hand. The machine used for this job resembles a long tong. This can vibrate. The harvester will reach the tong out to the trees, let the tong vibrate, and the olives will fall out. A net by the bottom of the tree catches the olives before they hit the ground.
Another mechanical method uses shakers attached to a tractor or two. Food manufacturers also use these shakers for picking grapes.
To harvest olives by hand, you’ll need to place a tarp around the tree on the ground. You can then reach up to the tree with a rake and rustle the olives onto the tarp. If you go the hand-picked route, you have three days to make the olives into oil. That’s because olives can sour if they oxidize for too long.
Most food manufacturers who want to make olive oil will seek out bigger olives early in the ripening process. The level of oil does decrease during ripening, even in larger fruits.
Step #2: Cleaning and Washing the Olives
Once a food manufacturer has their olives from the tree, they need to clean them. After all, olives are natural fruit, and as such, sometimes they’re not exactly squeaky clean. They may have debris, dirt, and other impurities. By washing them using water, these impurities disappear. This goes for pesticides as well, which could make olives toxic to consume in any form.
What about the other debris that can get lodged into the tender skin of an olive? To get rid of this, food manufacturers will occasionally use a hammermill. A type of mill, hammermills are machines that feature many small hammers. These hammers can break down tough solid materials either through crushing or shredding.
Besides olive oil production, hammermills have a place in waste management, commercial rock crushing, scrapping automobiles and parts, paper shredding, grain mills and sawmills, mulch pallet grinding, making fruit juice, defiberizing fluff pulp, and making ethanol plants.
Letting this olive debris pass through an oil separator can destroy its centrifugal decanter, soon rendering the machine useless. In fact, you might get only five years out of an oil separator that’s damaged to this degree when the machine should last for 25 years. That’s why hammermills can help.
Step #3: Taking off the Twigs, Leaves, and Stems
A hammermill could theoretically get rid of the twigs, leaves, and stems on olives as well, but it’s not often used for that purpose. Instead, a water bath can separate these parts if they’re weightier. For lightweight leaves and twigs, an air blower will force them right off the olive.
Step #4: Making Paste
The olives are now in the best possible condition. With no stems, leaves, or debris, the food manufacturer can move the olives to the next part of the oil-making process. With this, the whole fruits get mashed down until they become a paste.
Hammermills come in handy for this job, but they’re not the only machine food manufacturers will rely on. They will also use metal tooth grinders or stone mills. Metal tooth grinders, as the name tells you, are machines that have gnashing metal teeth that will chew the olives down until they come out the right consistency.
Stone mills, also called millstones, can break down grains like wheat. There are two millstones that work in conjunction with one another. The base stays stationary; this also goes by the name bedstone. Then there’s the grinding runner stone. This will rotate above the bedstone. In between the two stones, you’ll find a rynd, a metal piece shaped like a T. This attaches to the mace head, which connects to a main shaft. All these pieces let the millstone work. When feeding something through the millstone, the runner stone will break it down through its rotation.
The reason food manufacturers will mash olives like this is to produce oils. The part of the olive that holds the oil is known as the vacuole, which you can’t access without crushing or grinding the fruit. Vacuoles would otherwise stay hidden behind the flesh layer of the olive.
Step #5: Malaxing or Mixing
With the olives now made into a paste, they proceed to the the mixing or malaxing process. This is a shorter step, as it lasts for only 20, maybe 45 minutes.
What exactly is malaxing, you ask? That’s a good question.
With malaxing, the food manufacturer will use a mixer machine. This has a trough that moves the paste horizontally. The paste then passes through spiralized mixing blades. These blades have a very important job, as they take the portion of oil droplets the food manufacturer has to this point and increases them. This occurs by mixing the oil droplets together into a more sizable yield.
There’s two ways to get an even bigger yield than by malaxing alone. The first is to mix longer, up to 45 minutes, in the mixer machine. By malaxing for a lengthier period, more oil droplets can combine. The other method involves pouring in some water or heating up the mixing machine during malaxing.
That said, there’s downsides to these practices. By malaxing for 45 minutes or more, the olive oil begins oxidation. The longer this oxidation lasts, the less amount of time the oil can spend on store shelves before it goes bad.
By including water or heat in the malaxing process, the oil’s shelf life isn’t affected. However, the oil itself will be of a lower quality than oil that you do let mix for less time without water or heat.
Step #6: Isolating the Parts
The max yield of oil droplets obtained, it’s time to continue to the next part of the olive oil production process. This involves taking solids and vegetable water and isolating them from your oil.
How does the food manufacturer do that? By using pressing machines. If you ever check the packaging of your olive oil, sometimes it’s referred to as cold pressed. Once, oil could be first pressed. This referred to olives that went through a hydraulic or screw press. That resulted in a paste that got heated up. While first pressing could make olive oil well enough, it often lacked flavor purity, so the process got discarded.
Food manufacturers will still use cold pressing, although even that’s disappearing from the olive oil production process. With cold pressing, once again, the olives get mashed down into a paste. Then, they’re brought to room temperature, often through malaxing. With a horizontal decanter, the paste gets centrifuged. Cold pressing unfortunately affects flavor as well.
That’s why many food manufacturers will use centrifuges for the job, specifically three-phase ones. The phases can isolate the solids, water, and oil from one another. Some manufacturers will rely on two-phase centrifuges only. These work with a paste, often a wet one, and take the oil from it.
No matter the number of phases in the centrifuge machine, most of these machines have the capability to process the oil one more time. As the oil sits in a barrel or tank, gravity takes hold in a process known as racking.
Racking goes hand-in-hand with another clarification process, purging. The two aren’t the same, though, so don’t get them confused. With racking, the olive oil goes into a clean container from the top of another container, often through pumping. At the bottom of one container, water and sediment build up. They’re then separated from the oil.
With purging, the oil gets transferred to a specific tank with a bottom outlet. The manufacturer can then open the outlet to let the water and sediment out but not the oil. Without removing this sediment, olive oil often doesn’t look or taste as good and it doesn’t last as long on store shelves, so it’s an important process.
Step #7: Optional Extra Steps Before Bottling
By this point, you have your olive oil. Hopefully, it’s of a high quality and has a decently long shelf life. Not every manufacturer stops after isolating, racking, or purging, though. Others go on to do some extra things, such as filter the oil, process it further, put in additives, and de-pit it. Let’s talk about these more now.
With filtering, a food manufacturer will ensure there’s no sediment left in the olive oil. They use a mesh filter to do this. Filtering can improve the clarity of the oil as well as add to the product’s shelf life and boost its stability. In some instances, the olive oil might even have more antioxidants, up to five percent more. That’s not significantly more than olive oil that never went through the filtering process, then.
However, if you purge or rack the olive oil correctly the first time, there’s often no need for filtering. Also, sometimes even olive oil that is otherwise ready for sale doesn’t appear crystal clear. Filtering it won’t reduce this cloudiness, as this is just how some olive oil looks. That’s often due to several factors, including:
- The processing machinery the food manufacturer chose for the job
- How much oil went in the tank
- The temperature used to store the oil
- How much moisture the olives had during harvesting
- If all the sediment and other particles were removed from the olive paste, even the finer ones
- The hydration level of the oil
You can still sell cloudy olive oil, and it usually tastes about the same.
As we mentioned before, filtering is one of several finishing touches the olive oil might receive before it’s shipped out to stores. For instance, further processing might be done if the oil isn’t quite up to par with what the food manufacturer wants to sell. This processing includes:
- Adding activated carbon
- Deodorizing the oil if it’s particularly smelly
- Running the oil through a synthetic silica or diatomaceous earth treatment to cut out pesticides
- Bleaching the product if it has excess residual fatty acids, carotenoids, chlorophyll, and even pesticides
- Using caustic soda or alkali to trigger a reaction that boosts olive oil flavor
Additives and adjuvants can make for a bigger yield if the food manufacturer is unhappy with how much oil they have. They’ll often add solvents to the olive oil such as hexane, steam, and enzymes.
Talc also has a role in bettering oil yield. This additive, often favored in milling, works best if you have overripe or overwatered olives. This difficult fruit can have many other issues, such as:
- It emulsifies when milled. This allows water to combine with the oil droplets. The two liquids become inseparable, making the oil unusable. When adding talc to this difficult fruit, emulsification cannot take place.
- Agglomerating microgels can also appear during olive oil production. These gels have a combination of water and oil stuck together, again leaving food manufacturers without usable olive oil. With some talc, the microgels disintegrate, freeing the oils.
- When mixing the paste of difficult olives, the oil sometimes gets stuck within the paste walls. By using talc, not only do you get bigger droplets, but talc takes the cell wall oil and retains it.
Do keep in mind that if the olive oil is of a higher quality from the beginning, then there’s no often no need for additives or adjuvants like talc.
Last but certainly not least, food manufacturers may de-stone or de-pit an olive. It doesn’t happen often, mostly because it doesn’t seem to lead to higher quality olive oil than not de-pitting the fruit.
How long does it take to make olive oil?
Roughly how long does the above process take? Well, you’ll have to wait about three years for an olive tree to grow to the stage where the fruit blossoms. That’s on the shorter end, by the way. For other trees, it may be seven years before they grow fruit.
As we mentioned before, food manufacturers can only harvest olives at certain times, typically late summer through early winter. Then the malaxing process can last for 20 to 45 minutes, with shorter times preferred to retain olive oil taste and quality. The extraction or isolation process might occur within 24 hours.
In short then, making olive oil isn’t an instantaneous process, nor should it be. Given that the oil gets sourced from real olives, it’s understandable that nature plays a role in how long the entire process takes.
How is extra virgin olive oil made?
What about extra virgin olive oil? What is the manufacturing process like for this? First, let’s quickly define extra virgin olive oil. This is a finer version of standard olive oil. It costs more than other types of oil because of its high quality and superior taste.
For those reasons, the manufacturing process does not occur identically to that of regular olive oil. As an example, food manufacturers will never heat up the extra virgin olive oil to very high temperatures or expose the oil to other temperature fluctuations. This would lead to a lower-quality oil not acceptable if it’s going to earn the extra virgin label.
Also, the manufacturer will not rely on solvents or additives to make the oil look clearer, taste better, or last longer on store shelves. Most of the processing gets done via machine instead of through human intervention.
What about the olives used to make extra virgin olive oil? To produce only the best taste, food manufacturers must be incredibly picky about which olives will make the cut. These olives shouldn’t have ripened too much nor too little. They should have a bright color and fresh taste.
There’s little point in trying to extend the shelf life, by the way. Extra virgin olive oil only lasts for two years. Then, the quality begins gradually dropping to the point where you can no longer consider the oil extra virgin.