The olive oil yield will depend on many factors that we are going to analyze (olive variety, annual weather conditions, olive load, zone of crop, type of plantation, collection date, care of the olive tree, etc…).
Harvest time
The date of collection of the olives, has an important influence on the final olive oil yield obtained.
Although the oil in the olive grove, stops increasing as soon as the olive enters vegetative stop. As we saw in our publication Why do olives wrinkle?, olives lose moisture with the pass of the time.
Depending on the percentage of dry matter that the olive has, the yield of the olives in the mill will increase more or less with the passage of time.
Therefore, in the olive analysis, a reference to be taken into account is the fat yield on dry matter, that is, when the moisture present in the olives is completely eliminated. With this information, it is easier to observe the process of fat accumulation in olives.
Although the loss of moisture from the olives, reduces the kilos delivered and supposes a certain saving in transport and milling. This saving can be counterproductive, since the quality of the olive oil produced decreases and the overcomes the olive tree is encouraged.
On the other hand, with the passage of time, the olive falls to the ground and its collection is not always profitable.
Olive variety
High yield olive varieties can exceed 20% of oil on olives without wrinkling.
Among others, the following varieties produce high-yield olives, usually higher than 20%: Picual, Cornicabra, Verdial olive, Morisca, Arbequina, Farga, Picudo, Birdhouse…
With an average olive oil yield per kg between 150 and 200 g (15-20%) we can include: Empeltre, Hojiblanca, Blanqueta…
Varieties with low yields, less than 15%: Camomile Chamomile, Gordal Sevillana…
One thing is the gross yield and another is the net yield that is obtained when milling in the mill. Depending on the extractability of the variety and the machinery used, 3-4 performance points are lost in the alpeorujo. These losses are deducted from the gross yield of the olive to make the settlement. Some analyzes include an estimate of the industrial olive yield (estimate of the oil that the oil mill can extract from our olives).
Climatic conditions
The warm Mediterranean climate of southern Spain is ideal for the accumulation of olive oil in olives. Warm and sunny areas outperform cold and shady areas in production and performance.
In addition to the location’s own climate, annual variations can favor or worsen the accumulation of olive oil.
For example, the olive harvest 2018-2019, where the olive has not accumulated the usual amount of oil.
This has been due to several situations:
- Delay in flowering of the olive tree, due to the large amount of rainfall in spring.
- Lower biological activity of the olive tree, consequence of a colder summer than usual.
- Harvest above average.
As a consequence, the olive has had a significant delay in ripening and fatty olive yields have fallen 3-4 points compared to the 2017-2018 campaign.
Load of the olive tree
During the years of high load, the resources of the olive tree must be distributed among a large number of fruits. This situation causes delays in the ripening of the olives, which reach a lower olive oil yield per kg than a year with medium-low load.
Type of plantation
The type of plantation influences the olive lighting and the kg of olives produced per hectare. In this way, the yield decreases as planting density increases.
This is one of the reasons why the fat yield of a variety planted in super hight density olive grove is lower than that of the same variety grown in a traditional olive grove.
How do olive care affect olive yield?
The care of the olive tree has an important influence on the yield of the olive.
Pruning the olive tree: To increase the yield, good lighting of the branches should be favored.
Olive tree fertilizer: Trees with nutritional deficiencies have difficulty producing photoassimilates. This negatively influences the yield and the size of the fruits is smaller than it should.
Water stress: Being subjected to water stress, the olive tree reduces its biological activity to reduce water consumption. On the other hand, plantations with a sufficient water supply may produce larger olives, with a higher olive yield on dry matter.
Pests and diseases of the olive tree: Pests and diseases weaken the olive tree, reducing its potential harvest of olives and olive oil.
Sampling
When taking samples for analysis, this should be as representative as possible of the item. To do this, it is recommended to use random and automatic systems for sampling (saucepans). The sample size will depend on the size of the item, the automatic systems collect olives during the entire weighing phase. 1 kg is representative enough to analyze a batch between 2,000 and 3,000 kg.
Olive yield analysis
Performing analysis to calculate olive oil yield, is a common practice in most Spanish oil mills and cooperatives.
The result of the analysis is taken as a starting point to calculate the net yield of the olives.
In the case of cooperatives, on the one hand the real yield is calculated (Total oil produced / kilos of milled olives) and on the other a weighted average of the yields obtained in the analyzes is made.
Cooperatives: In cooperatives, to obtain the correction points, the real performance obtained is subtracted from the gross analysis performance. For example, if the average gross yield is 19.8% and the actual yield is 17%, we lose an average of 2.8 oil points in the alpeorujo. At the time of settlement, the gross performance of the partner is subtracted 2.8 points and thus the net return for each partner is obtained.
Oil mills: Oil mills do not spin so thin and will apply the correction coefficient they deem appropriate, according to their machinery and the type of olive received. Normally between 3 and 4 points.
Although performance measurement equipment is expensive, it is essential to perform periodic analyzes of the alpeorujo in the mill. In this way, it can be verified that the oil extraction is being carried out well and that there is no unnecessary loss of performance.
In addition, many oil mills and cooperatives have their own laboratory, equipment and personnel to analyze the performance of items received.
However, in many cases it is preferable to send the samples to a specialized laboratory.
In this way, the analyzes are carried out with equipment with greater precision and in a more impartial way.
How much does it cost to perform a performance analysis?
As we see in the following table, the price of the performance analysis varies depending on the number of samples analyzed and the type of analysis performed.
We asked the LABISER laboratory , which kindly responded to us with your rates for the 2018-2019 campaign.
NUMBER OF SAMPLES | FAT + HUMIDITY | FAT + HUMIDITY + ACIDITY |
| 1 to 25 | € 5.00 | € 7.00 |
| 26 to 100 | € 4.00 | € 6.00 |
| 101 to 500 | € 3.00 | € 5.00 |
| 501 to 1000 | € 2.50 | € 4.00 |
| 1001 to 2000 | € 2.25 | € 3.75 |
| 2001 onwards | € 2.00 | € 3.50 |
The price does not include the 21% VAT and the costs we assume for the delivery or shipment of the samples. The size of sample currently recommended by the laboratory is 1 kg.
The results are delivered within 24-48 hours after receiving the samples.
Recommended reading
If you liked our publication abaut olive oil yield, surely one of the following topics may be of your liking:
What is the most profitable olive variety?
How do you keep a young and productive olive grove?
Electric or gasoline olive rods?
What is and how is the degree of acidity for olive oil calculated?
Warning
We have translated the information on our website from Spanish to English. Note that some words may have seen their meaning altered during their translation.