Science

Organoleptic assessment of virgin olive oil

Organoleptic assessment of virgin olive oil
  • PublishedNovember 21, 2022

By Efi Christopoulou*, [GR]

*Expert chemist of IOC and EU and IOC panel leader, member of the Scientific Society of Olive Encyclopaedists (4E)  

efic52@gmail.com

INTRODUCTION

Since ancient times, the flavor and taste of a food has been one of the most important criteria for consumers to buy.

Various methods have been developed over time to evaluate the organoleptic characteristics of several foods.

In 1982, the International Olive Oil Council, within the framework of its aims, launches a program for the development and establishment of a method for the organoleptic assessment of virgin olive oil. Over the years the initially adopted method has undergone modifications. The current official organoleptic method is the Revision 10 of COI/T.20/Doc.No.15 of the International Olive Council (IOC).

 

what is VIRGIN OLIVE OIL?

“Virgin olive oil is the oil obtained from the fruit of the olive tree solely by mechanical or other physical means under conditions, particularly thermal conditions, that do not lead to alterations in the oil, and which has not undergone any treatment other than washing, decantation, centrifugation and filtration.“

 

That is, Virgin Olive Oil is the juice of the fruit of olive tree, of the tree that announces delight, peace and victory. However, there are some categories of it and some other categories produced by treating the non-edible virgin olive oil as it is or by processing the by-product of olives. Consequently, before going any further it would be useful at least the various categories of virgin olive oils to be referred and so have a clear view of what each category means from the very start.

The categories of olive oils and olive-pomace oils are defined by International Standards according to their values of quality criteria, which have established for the quality control of the above products.

For olive oils and olive pomace oils, the International Standards are the Trade Standard of the International Olive Council (IOC) and the CODEX ALIMENTARIUS standard. To these Standards the Regulation (EEC) 2568/91 should be added, which is applied to the European market and is harmonized with the IOC TRADE STANDARD. These standards have defined the physico-chemical and organoleptic characteristics of each category and the methods for their determination.

The quality criteria of virgin olive oil according to the Regulation (EEC) 2568/91, are:

 

In addition, in accordance with the Regulation (EEC) 2568/91, the olive fruit, depending on its quality, produces one of the following categories in the olive mill:

 

Extra virgin olive oil is the top category of virgin olive oils with high biological and nutritional value.

Lampante olive oil is not suitable for human consumption as it is and after its processing in the refinery (neutralization, deodorization and discoloration) it produces refined olive oil.

 

GENERAL FOR THE ORGANOLEPTIC METHOD

Virgin Olive Oil is the only food in which, according to International Standards, sensory analysis is a mandatory criterion for assessing its quality.

It evaluates quality attributes that are easily perceived by the consumer.

Organoleptic assessment or sensory analysis of virgin olive oil is the detection and the description of both qualitative and quantitative flavour characteristics of virgin olive oil using human senses (smell and taste).

The official method for the organoleptic assessment of virgin olive oil directly use a panel of tasters (8-12) selected, well-trained and controlled, analogous to an instrument.

Since the tasters of the panel is the measuring instrument in sensory analysis, the IOC has adopted strict procedures for the selection, initial training and continuous quality control of the tasters in order for the panel to produce reliable results.

For the correct application of the organoleptic method, there are specifications for the glass used for oil tasting and for the test room. In addition, instructions are provided for the tasters and for the control of the conditions during the performance of the organoleptic assessment.

 

SPECIFIC VOCABULARY FOR VIRGIN OLIVE OIL

The IOC has adopted specific vocabulary for virgin olive oil, including terms and definitions for negative (defects) and positive attributes of virgin olive oils.

According to this specific vocabulary and the profile sheet provided by the method for use by the tasters, the number of the used terms is 18 and the attributes are subdivided into three groups.

 

The researches have prove that the compounds which are responsible for the negative organoleptic attributes are not found in good quality olive fruit or in virgin olive oils produced following good manufacturing processes.

These compounds are secondary products of oxidation or of enzymatic reactions. The defects of virgin olive oil are generated from various causes. The presence of each one of the defects is the result of a bad applied practice. For example the defect fusty is caused by an advanced stage of anaerobic fermentation of piled olives, the defect musty is caused by large numbers of fungi and yeasts developed in olives stored in humid conditions for several days,  the defect rancid is caused by an intense process of oxidation of oils etc. For this reason,  a long list of words is used for defects. Idendifying the name of each defect is like determining the process that caused this defect. This is very useful for the producers and/or packers and/or traders of the oil being tasted, because they can be informed about the possible defect detected in their oil and the responsible practice that caused this defect. This knowledge will help them to improve the quality of the oils they produce or distribute.

On the contrary, the positive attributes in the specific vocabulary and the profile sheet provided by the method for use by the tasters are the pleasant sensation fruity together with the attributes bitter and pungent.

Bitter is the characteristic primary taste of oil obtained from green olives or olives turning colour and pungent is the biting tactile sensation characteristic of oils produced at the start of the crop year, primarily from olives that are still unripe.

With the name fruity we mean set of olfactory and retronasal olfactory sensations characteristic of the oil which depends on the variety and comes from sound, fresh olives, either ripe or unripe. Despite the fact that various varieties worldwide exhibit variations regarding the type of fruitiness, the name for this positive attribute cannot be differentiated according to the variety.

 

TASTING TECHNIQUE

As mentioned above, the organoleptic assessment of virgin olive oils includes the tasting of this oil by using the human sense organs of smell and taste.

Smell

The taster shall pick up the special glass for oil tasting, keeping it covered with the watch-glass, and shall bend it gently; they shall then rotate the glass fully in this position so as to wet the inside as much as possible.

Once this stage is completed, they shall remove the watch-glass and smell the sample, taking slow deep breaths to evaluate the oil. Smelling should not exceed 30s.

They shall concentrate thoroughly on detecting the positive or negative “notes” that emerge. They should bring in his mind all the characteristic odors of olive oil, which they have been familiar to, and start thinking as to how to express those notes in terms of the descriptors listed in the specific vocabulary and the profile sheet provided by the method for use by the tasters. If no conclusion has been reached during this time, they shall take a short rest before trying again.

Taste

When the olfactory test has been performed, the taster will then judge the flavor (overall olfactory -gustatory-tactile sensation).

To do so, they shall take a small sip of approximately 3 ml of oil. It is very important to distribute the oil throughout the whole of the mouth cavity, from the front part of the mouth and tongue along the sides to the back part and to the palate support and throat, since it is a known fact that the perception of tastes and tactile sensations varies in intensity depending on the area of the tongue, palate and throat.

Taking short, successive breaths, drawing in air through the mouth, enables the taster not only to spread the sample extensively over the whole of the mouth but also to perceive the volatile aromatic compounds via the back of the nose by forcing the use of this channel.

The tactile sensation of pungency should be taken into consideration. For this purpose, it is advisable to ingest the oil.

In order to eliminate a “taste” they will use a slice of apple, or in any case, it is essential to rinse his mouth carefully and to wait until he starts to secrete saliva again as normal.

Then, they will enter in the profile sheet provided the intensity with which they perceives each of the negative and positive attributes.

 

CLASSIFICATION OF VIRGIN OLIVE OIL REGARDING ORGANOLEPTIC CHARACTERISTICS

The organoleptic method is only applicable for the classification of virgin olive oils according to the perceived intensity of the predominant defect and the presence or absence of the fruity attribute. Particularly, according to Reg. (EEC) 2568/91:

 

Classification of virgin olive oil (according to Reg. (EEC) 2568/91) 

 

CONCLUSIONS

Organoleptic assessment of virgin olive oil by the official method is an objective analytical parameter that occupies the same position as other chemical quality parameters and cannot be replaced by chemical quality parameters, nor has an instrumental method been found to replace it.

This method is objective and produces results with known margins of errors, as any analytical method, because:

  • The physical conditions of the test have been properly controlled and standardized.
  • The psychophysiological factors have been appropriately compensated for by preventing biases or tendencies from appearing and by ensuring that the panel has the necessary number of well-trained assessors.
  • The results are statistically processed.

The organoleptic evaluation is an irreplaceable quality criterion of virgin olive oil, because chemical quality criteria are not sufficient on their own to evaluate the quality of a virgin olive oil and there are currently no physicochemical methods to determine all the organoleptic attributes of virgin olive oils or the weakening or strengthening of the combination of stimuli, which is perceived through the sense organs.

The long experience in the application of organoleptic method reveals that it is a very effective tool to substantiate the true quality of virgin olive oil, since it detects bad practices during

  • the cultivation, harvesting, transporting and storing of the olives,
  • the processing of olives into oil and
  • the storage, transportation and packaging of olive oil.

Therefore, the organoleptic assessment by a panel of tasters is, no doubt, absolutely necessary for and beneficial to the consumers and traders as well. It has helped to improve the quality of virgin olive oil and thus to ensure the good reputation and marketing of the product on the International Market.

 

END NOTE BY THE AUTHOR

I have been working on the organoleptic method of virgin olive oil since its first steps in 1982 till nowadays.

Μy parallel work on olive oil chemistry and organoleptic evaluation for so many years, made me to devote and love olive oil, feelings which get stronger and deeper the more you get acquainted with this precious product.

 

 

Italia Olivicola
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Vassilis Zampounis