Olive oil acidity is a topic that is as widely discussed as it is misunderstood by consumers and even by home cooks. In this article, we'll clear up some of the most common misconceptions.
Contents
➜ Confusion Between Acidity and Flavor
➜ Maximum Acidity Levels by Type of Olive Oil
➜ What Is the Acidity of Las Valdesas Olive Oils?
➜ Why Don't Acidity Levels Appear on Olive Oil Labels Anymore?
Introduction
Olive oil is naturally formed within the olive fruit in the form of triglycerides. Each triglyceride consists of three fatty acids linked to a molecule called glycerol.
The bond between glycerol and the three fatty acids is weak, so when exposed to oxygen or other harsh conditions, it breaks and releases the three fatty acids. As a result, the olive oil begins to deteriorate. Acidity measures the amount of these free fatty acids present in the olive oil. Therefore, acidity is a general indicator of the quality of virgin olive oils.
✓ The lower the acidity of a virgin olive oil, the higher its quality.
Acidity, the parameter shown on bottle labels, measures the amount of free oleic acid, the most abundant fatty acid in olive oil. Acidity is expressed as the percentage by weight of free oleic acid in the total amount of olive oil. On labels it should be expressed as a percentage (%), although it has traditionally been expressed in degrees (°).
Confusion Between Acidity and Flavor
There is considerable confusion among consumers about olive oil acidity. Most people tend to confuse it with the intensity of the oil's flavor, whether those flavors are pleasant or unpleasant. In fact, free fatty acids have no taste. We believe this confusion is due to two reasons:
1.- People confuse acidity with one of the basic tastes: sweet, salty, sour, and bitter. In reality, they are unrelated, and acidity, as a quality parameter, cannot be detected by tasting.
2.- Although acidity is a quality parameter that applies only to Virgin Olive Oils, in the past the industry used it on the labels of 'olive oils', which are blends of refined olive oil and virgin olive oil. Therefore, the higher the proportion of refined oil in an olive oil, the lower its acidity and flavor, since refined olive oils have neither flavor nor acidity.
Maximum Acidity Levels by Type of Olive Oil
The acidity level is one of the main parameters used to classify the quality of the different types of virgin olive oil:
Extra Virgin Olive Oil: The acidity must be less than or equal to 0.8%.
Virgin Olive Oil: The acidity must be less than or equal to 2.0%.
All virgin olive oils with an acidity above 2.0% are classified as lampante olive oil.
What Is the Acidity of Las Valdesas Olive Oils?
At the end of each harvest, we analyze the acidity of our olive oils.
Our Arbequina, Picual, and Hojiblanca olive oils typically have a free acidity below 0.20%. (The lowest value we have ever recorded is 0.14%.)
Our Frantoio and Manzanillo olive oils typically have a free acidity between 0.4% and 0.6%, all well below the extra virgin limit of 0.8%.
You can view the acidity of our olive oils on the analysis page.
Why Don't Acidity Levels Appear on Olive Oil Labels Anymore?
Some years ago, acidity was used as the main quality claim on olive oil labels, although not on virgin olive oils.
Since acidity caused confusion among consumers and did not necessarily reflect the quality of an olive oil, the regulations changed. Today, if a producer wishes to include the acidity of an olive oil on the label, they must also include other quality parameters such as peroxide value, wax content, and ultraviolet absorbance (K270, K232, and ΔK).
As a result, rather than including these additional quality parameters, most producers simply removed acidity from their labels. Initially, they replaced it with generic figures such as 0.4 and 1.0, and later with terms such as "intense" and "mild".
Today, only high-quality extra virgin olive oils generally include the acidity level on the label, together with other quality parameters such as peroxide value, wax content, and ultraviolet absorbance.
How and Why Does Acidity Increase in Virgin Olive Oil?
As we have seen, the acidity of olive oil increases when it is exposed to oxygen or other harsh conditions. Let's look at how triglycerides, the main component of olive oil, can break down throughout the life of the oil.
1.- Olive oil inside the olive fruit.
Initially, triglycerides are protected inside the olive fruit from atmospheric oxygen by the skin of the olive. If the skin is damaged, oxygen enters the fruit and begins to break down the triglycerides, causing the acidity to increase. The skin may be damaged by pests, hail, fruit falling to the ground, damage during transportation, and other causes. As a result, olive oil made from healthy olives, free from pest damage and harvested directly from the tree, will have low acidity.
Another critical stage is storing the olives before milling. When the olives arrive at the mill, they are unloaded into metal hoppers. The olives at the bottom are crushed by the weight of those above them, allowing oxygen to begin the oxidation process. If the olives remain in these hoppers for too long before milling, acidity increases significantly, and fermentation may even begin. This problem becomes even more pronounced as the olives ripen because they become softer and are more easily crushed.
2.- The milling and production process.
During processing at the mill, the olive paste comes into contact with air and is therefore exposed to oxidation. The longer the milling process takes, the more the olive paste oxidizes. Temperature also plays an important role. The higher the temperature, the faster the oxidation reactions occur and, consequently, the acidity increases. (Learn more about olive oil production).
3.- Storage in the olive oil tanks.
Once the olive oil has been produced and stored, oxidation can continue. If the storage tanks are not airtight, or even if they are airtight but not completely full, air remains inside the tank. Some olive mills replace this air with nitrogen to preserve the olive oil in optimal condition.