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Why is Olive Oil Bitter?

olive oil bitter

If olive oil is bitter, does it mean it is of the highest quality? What makes olive oil bitter? How bitter must it really be?

Some people say that the bitter taste of olive oil is a proof of quality. Others say that bitter olive oil is very nutritional. In fact, bitterness is simply the signature of the olive variety. And sometimes, olive oil is bitter because of some mistakes during the oil extraction. But let’s take it step by step.

The three positive attributes of the olive oil taste are fruitiness, bitterness and pungency.

Only extra virgin olive oil will naturally have these characteristics. Fruitiness refers to the aromatic qualities of the oil which can express freshness, flavor of apples or nuts, green herbs, grass etc. The bitter and pungent taste of olive oil are given by the amount of some polyphenols.

It is usually believed that the more polyphenols (antioxidants) the oil has, the higher the quality will be, as well as bitterness. It is more accurate to say that the higher amount of antioxidants gives a stronger taste of bitterness when we compare different types or brands of extra virgin olive oil made of the same olive cultivar. But as you can see in the table below, sometimes an olive cultivar with very high content of polyphenols, has mild bitterness (Koroneiki), while another cultivar with lower content of polyphenols than the first one, has higher bitterness and very strong pungency (Frantoio). The same can be observed in the case of Coratina cultivar.

cultivar polyphenols fruitiness bitterness pungency appreciation
Picual very high fruity medium medium low-high
Hojiblanca medium medium low mild medium
Cornicabra very high very fruity medium medium high
Frantoio medium-high very fruity medium strong very high
Leccino medium medium low low medium
Moraiolo very high strong medium medium medium
Coratina very high strong bitter pungent very high
Koroneiki very high strong mild mild very high

This happens because bitterness and pungency (“picante” sensed in the throat sometimes for 20 minutes) are first of all related to the type of olive cultivar and its components. Similar in polyphenols content cultivars are still different as being more or less bitter or pungent.

The explanation is that not all antioxidants in the olive oil give it a bitter or pungent taste. Oleuropein and flavenoids make olive oil bitter. Olive oil contains at least 30 different phenolic compounds and approximately 280 volatile compounds which also influence the flavor and taste. Some of these compounds, when present, will give a sweeter taste, others will make the oil bitter or pungent. Unsaturated aldehydes will make the oil taste rancid and so on. Imagine two types of olive oil, one containing more caffeic acid than usually and another having in its composition more vanilic acid than usually. Obviously, even with the same amount of oleuropein and flavenoids, one will be strongly bitter and the other slightly bitter.

Bitterness also softens and mellows with age. Olive oil obtained from the same olive variety has a more bitter taste if it is an early harvest oil. And still, the same oil, after some months, becomes less bitter.

Except this, when higher temperature than 27 degrees Celsius is used in the oil extraction, the bitterness and pungency increase, meaning that a strong bitter taste might come from the errors occurred in the processing.

Conclusion: A good olive oil must have a bitter taste but strong bitterness does not necessarily prove that the oil is of highest quality. Strong bitterness and pungency come from a high amount of particular polyphenols and the presence of some volatile compounds that give this taste.

A high quality extra virgin olive oil must have a pleasant bitterness and pungency.


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