How to Recognize Good Extra-Virgin Olive Oil
You can get decent olive oil from any olive-producing area.
However, you can only produce high-quality oil that brings out the oil’s distinctive attributes when all the agricultural and technological phases of production have been properly completed.
A variety of fundamental chemical criteria are applied to determine the grade of the olive oil. It is essential to do an organoleptic test to determine the oil’s chemical and sensorial attributes and whether the oil’s physical attributes are positive or negative.
Below is a table illustrating all the different types of olive oil, their names, pH (a basic assessment criterion for oil) and extraction method.
Olive oil intended for sale that has not been blended or undergone complex processing is called virgin olive oil.
Virgin Olive Oils
Below, we explain how and why an oil is given the grade “virgin olive oil”
Virgin olive oil is obtained from olive fruit using only natural (mechanical or physical) processes at a temperature that does not alter the oil and involves nothing but washing, decanting, centrifugation and filtering.
Chemical and sensory criteria are applied to grade virgin oils as: extra virgin, virgin and lampante.
Extra-virgin Olive Oil
Extra-virgin olive oil has a pH of no more than 0.8%, no defects and positive fruity attributes based on a sensory assessment called a “panel test” carried out by professionals who assess oil quality by tasting it.
Virgin olive oil
Virgin olive oil has a pH of around 2% (clearly higher than extra-virgin olive oil), slight defects and fruity attributes.
Lampante olive oil
Lampante olive oil has a pH higher than 2%. The panel test shows more marked defects and no fruity attributes.
Lampante olive oils are not meant for consumption. However, these oils are treated and undergo chemical refining processes, then are treated and blended with extra-virgin olive oil to make virgin olive oil.
What are the attributes that define a good extra vergin olive oil?
Free acidity
(the percentage of free fatty acids in oil)
This attribute is mainly determined by the quality of the olives. It guarantees the oil’s freshness and is an indicator of how healthy the olives are.
Free acidity forms when the olives’ cellular structure begins to break down, when the oil normally contained in the vacuole comes into contact with cell enzymes, which free the fatty acids from the triglycerides.
Oil pH can be compromised by external factors such as olive fruit fly damage or internal factors such as improper storage.
Extra-virgin olive oil pH must not exceed 0.80 g per 100 g. The ideal pH of high-quality oil is around 0.1-0.3%.
Virgin olive oil has low pH because the olives are harvested during the first ripening phase, when they are still fresh and green.
When olives are harvested during the ripening phase, they are rich in polyphenols and antioxidants, which are excellent for your health because they prevent cell aging.
This means that low pH is essential to determine the grade of the oil. Though, low pH is not enough to guarantee an optimal product. For this, you need to find out if additional quality criteria are met by doing an organoleptic test. If you remember from the table, even non-virgin oils have low pH. However, this is because these oils have undergone chemical processes and refining. In order to recognize genuine extra-virgin olive oil, you need to do an organoleptic test.
Organoleptic test
In order to objectively assess oil quality, common terminology has been established which apply to all olive-producing countries and goes beyond just generic taste, setting out clear criteria for each grade of olive oil.
There are two parts to this test: the sensory assessment (done by the taster) and the grading of the sample (done through calculation).
Sensory assessment
The first phase is carried out by an assessment group or “panel” whose job is to taste the oil and assess its sensory attributes.
Judging an oil entails objectively describing both its positive and negative attributes.
The positive sensory attributes of extra-virgin olive oil are: fruity, bitter and pungent.
The negative sensory attributes are: fusty, vinegary or metallic.
Sample grading
Not only do the sensory attributes of the oil need to be assessed, the organoleptic properties need to be analyzed as well in a lab.
What are the organoleptic properties of oil and what do they tell us?
Peroxide value: A peroxide value that is no greater than 20 meq/2 kg guarantees the oil is fresh. Peroxides are primary oxidation products and their value determines oil quality. These values are affected by sunlight, high temperatures and traces of oxygen in the oil. So, a high peroxide value may be an indicator of improper olive treatment and storage.
Spectrophotometric index (K232, K270 and DK respectively ≤2.5, 0.22 and 0.01): This index provides information on the oil’s degree of oxidation, which is used in turn to determine the oil’s age.
Wax content: This criterion helps determine whether pomace oil has been added to virgin olive oil, which results in higher wax content due to extraction using solvents. In extra-virgin olive oil wax content should be ≤ 250 mg/kg.
Fatty acid ethyl esters (≤ 35 mg/kg): This value gives us information about olive health and whether fermentation processes are underway.
We hope this helps you understand the organoleptic attributes of olive oil and how oil is assessed so you can recognize genuine, quality extra-virgin olive oil.
Beware of imitation oils!