Why must good olive oil be bitter?

Why must good olive oil be bitter?

Aging of Olive Oil: A Natural Process Affecting Taste and Quality

The aging of olive oil is a natural process that significantly influences its taste and quality. It leads to changes in organoleptic characteristics: from the weakening of fresh fruit aromas, which are replaced by a mature fruity taste, to the disappearance of sharpness/spiciness and ultimately bitterness as well.

The first taste to diminish is the sensation of sharpness, while the bitter taste, before disappearing, increases its intensity during storage.

These positive attributes of bitterness and pungency (bitterness, pungency) are associated with the presence of phenolic compounds (secoiridoids), which undergo chemical changes until they lose their antioxidant capacity, transforming into inactive quinones. At this point, the oxidation process begins, leading to the appearance of the taste flaw of rancidity. This process can be divided into two stages: primary oxidation, visible spectrophotometrically at a wavelength of 232 nm (K232 marker in biochemical testing), and secondary, visible at the K270 marker and in sensory testing.

The taste of bitterness is not well tolerated by consumers, unlike spiciness. Oleuropein is the main source of the olive fruit's bitterness. It is a polyphenol very beneficial for human health and is one of the key active ingredients present in extra virgin olive oil. This natural substance offers a range of health benefits such as:

Antioxidant action: Oleuropein is a strong antioxidant that helps combat free radicals in the body, which can reduce the risk of chronic diseases and aging processes.

Support for heart health: Oleuropein helps lower blood pressure, reduces bad LDL cholesterol levels, and improves vascular health, contributing to overall heart protection.

Anti-inflammatory properties: With its anti-inflammatory properties, oleuropein can help alleviate inflammatory conditions in the body, which is beneficial for many health conditions.

Immune system support: Oleuropein exhibits antibacterial and antiviral activities, which may support the body's natural defense against infections.

Improvement of metabolic health: Research suggests that oleuropein may have a positive impact on regulating blood sugar levels, which is important for people with insulin resistance or diabetes.

Neurological protection: Some studies indicate that oleuropein may have a beneficial effect on brain health, including potential protection against neurodegenerative diseases such as Alzheimer's disease.

Anticancer properties: Oleuropein may contribute to the prevention and inhibition of the development of certain types of cancers, though further research is required.

That's why good quality extra virgin olive oil should be bitter. Moreover, olive oil is bitter from the beginning of production and even under the best storage conditions, its intensity increases.

Changes in Phenolic Compounds and Their Impact on Olive Oil

During aging, key phenolic compounds in olive oil, known as secoiridoids, undergo degradation. These compounds are responsible for the antioxidant properties of olive oil, but over time they lose their effectiveness, transforming into inactive quinones. This process leads to the oxidation of olive oil, which causes the emergence of undesirable flavors, such as rancidity. Understanding this process is important for maintaining the quality of olive oil.

Bitterness in Olive Oil: Consumer Perception

The way consumers perceive bitterness in olive oil varies. Many people have a natural aversion to the taste of bitterness, stemming from an evolutionary response to potentially harmful or toxic substances, such as hemlock or belladonna.

Role of TAS2R Taste Receptors in Bitterness Perception

Human taste senses are regulated by TAS2R receptors, which are diverse and can react to a wide range of bitter substances. In mammals, including humans, these receptors are particularly sensitive to bitterness, which is significant in the context of studying and understanding how olive oil components affect its final taste.

Scientific Research on Olive Oil

Scientists strive to better understand how the taste of olive oil changes with aging, as well as how different phenolic compounds interact with TAS2R receptors. This research is crucial for producers to be able to produce the highest quality olive oil that meets consumers' expectations in terms of taste and health properties.

Tasting Extra Virgin Olive Oil


Clean your palate with water or a piece of apple. Pour about 15 ml of olive oil into a tasting glass with an IOC certificate (International Olive Council) and cover it with a transparent lid. You can also use another opaque glass. The color of olive oil does not affect its quality, for tasting a "cobalt blue" colored vessel is used (the human brain automatically reads the color green as more positive than other shades).

Visual Evaluation

Hold the glass with one hand to warm the sample for one minute, while holding the lid with the other hand.


Cover the glass with your hand and gently shake it. Uncover and smell the aroma of the olive oil. Note fruity, herbal, or other characteristic scents.


Spread about 3 ml of olive oil throughout your mouth, taking short breaths through your teeth. Exhale through your nose to fully sense the complex aromatic compounds of the oil (retro-nasal olfaction).


Feel the bitterness! Swallow a small amount of the sample to detect possible spiciness in the back of the throat. Enjoy the spiciness! Reflect on the overall impression. Assess its taste complexity, harmony, and the persistence of the aftertaste.


The real pleasure of tasting comes from slowly and attentively experiencing each stage. Bitterness and spiciness are positive attributes associated with the quality and healthy properties of good extra virgin olive oil.


Source: Teatro Naturale, Terra Creta


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