METHOD FOR THE ORGANOLEPTIC ASSESSMENT OF VIRGIN OLIVE OIL
COI/T.20/Doc. No 15/Rev. 7 February 2015
The purpose of this international method is to determine the procedure for assessing the organoleptic characteristics of virgin olive oil and to establish the method for its classification on the basis of those characteristics.
2. FIELD OF APPLICATION
The method described is only applicable to virgin olive oils and to the classification of such oils according to the intensity of the defects perceived and of the fruitiness, as determined by a group of tasters selected, trained and monitored as a panel.
It also provides indications for optional labelling.
3. GENERAL BASIC VOCABULARY FOR SENSORY ANALYSIS
Refer to the standard COI/T.20/Doc. no. 4 “Sensory Analysis: General Basic Vocabulary”.
4. SPECIFIC VOCABULARY FOR VIRGIN OLIVE OIL
4.1. Negative attributes
Fusty/muddy sediment: Characteristic flavour of oil obtained from olives piled or stored in such conditions as to have undergone an advanced stage of anaerobic fermentation, or of oil which has been left in contact with the sediment that settles in underground tanks and vats and which has also undergone a process of anaerobic fermentation.
Musty-humid-earthy: Characteristic flavour of oils obtained from fruit in which large numbers of fungi and yeasts have developed as a result of its being stored in humid conditions for several days or of oil obtained from olives that have been collected with earth or mud on them and which have not been washed.
Winey-Vinegary: Characteristic flavour of certain oils reminiscent of wine or vinegar. This flavour is vinegary mainly due to a process of aerobic fermentation in the olives or in
Acid-sour: olive paste left on pressing mats which have not been properly cleaned and leads to the formation of acetic acid, ethyl acetate and ethanol.
Rancid: Flavour of oils which have undergone an intense process of oxidation.
Frostbitten olives (wet wood): Characteristic flavour of oils extracted from olives which have been injured by frost while on the tree.
4.2. Other negative attributes
Heated or burnt: Characteristic flavour of oils caused by excessive and/or prolonged
heating during processing, particularly when the paste is thermally mixed, if this is done under unsuitable thermal conditions.
Hay–wood: Characteristic flavour of certain oils produced from olives that have dried out.
Rough: Thick, pasty mouthfeel sensation produced by certain old oils.
Greasy: Flavour of oil reminiscent of that of diesel oil, grease or mineral oil.
Vegetable water: Flavour acquired by the oil as a result of prolonged contact with vegetable water which has undergone fermentation processes.
Brine: Flavour of oil extracted from olives which have been preserved in brine.
Metallic: Flavour that is reminiscent of metals. It is characteristic of oil which has been in prolonged contact with metallic surfaces during crushing, mixing, pressing or storage.
Esparto: Characteristic flavour of oil obtained from olives pressed in new esparto mats. The flavour may differ depending on whether the mats are made of green esparto or dried esparto.
Grubby: Flavour of oil obtained from olives which have been heavily attacked by the grubs of the olive fly (Bactrocera oleae).
Cucumber: Flavour produced when an oil is hermetically packed for too long, particularly in tin containers, and which is attributed to the formation of 2,6 nonadienal.
4.3. Atributos positivos
Fruity: Set of olfactory sensations characteristic of the oil which depends on the variety and comes from sound, fresh olives, either ripe or unripe. It is perceived directly and/or through the back of the nose.
Bitter: Characteristic primary taste of oil obtained from green olives or olives turning colour. It is perceived in the circumvallate papillae on the “V” region of the tongue.
Pungent: Biting tactile sensation characteristic of oils produced at the start of the crop year, primarily from olives that are still unripe. It can be perceived throughout the whole of the mouth cavity, particularly in the throat.
4.4. OPTIONAL TERMINOLOGY FOR LABELLING PURPOSES
Upon request, the panel leader may certify that the oils which have been assessed comply with the definitions and ranges corresponding to the following adjectives according to the intensity and perception of the attributes.
Positive attributes (fruity, bitter and pungent): According to the intensity of perception:
– Intense, when the median of the attribute is more than 6;
– Medium, when the median of the attribute is between 3 and 6; – Light, when the median of the attribute is less than 3.
Fruity: Set of olfactory sensations characteristic of the oil which depends on the variety of olive and comes from sound, fresh olives in which neither green nor ripe fruitiness predominates. It is perceived directly and/or through the back of the nose.
Greenly fruity: Set of olfactory sensations characteristic of the oil which is reminiscent of green fruit, depends on the variety of olive and comes from green, sound, fresh olives. It is perceived directly and/or through the back of the nose.
Ripely fruity: Setofolfactorysensationscharacteristicoftheoilwhichisreminiscentofripefruit, depends on the variety of olive and comes from sound, fresh olives. It is perceived directly and/or through the back of the nose.
Well balanced: Oil which does not display a lack of balance, by which is meant the olfactory– gustatory and tactile sensation where the median of the bitter and/or pungent attributes is two points higher than the median of the fruitiness.
Mild oil Oil: for which the median of the bitter and pungent attributes is 2 or less.
5. GLASS FOR OIL TASTING
Refer to the standard COI/T.20/Doc. no. 5, “Glass for Oil Tasting”.
6. TEST ROOM
Refer to the standard COI/T.20/Doc. no. 6, “Guide for the Installation of a Test Room”.
The following accessories, which are required by tasters to perform their task properly, shall be supplied in each booth and shall be within easy reach:
- glasses (standardised) containing the samples, code numbered, covered with a watch-glass and kept at 28 oC ± 2 oC;
- profile sheet (see Figure 1) on hard copy, or on soft copy provided that the conditions of the profile sheet are met, together with the instructions for its use if necessary;
- pen or indelible ink;
trays with slices of apple and/or water, carbonated water and/or rusks; glass of water at ambient temperature;
sheet recalling the general rules listed in sections 9.4 and 10.1.1; spittoons.
8. PANEL LEADER AND TASTERS
8.1. Panel leader
The panel leader must be a suitably trained person with an expert knowledge of the kinds of oils which he or she will come across in the course of their work. They are the key figure in the panel and responsible for its organisation and running.
The work of the panel leader calls for basic training in the tools of sensory analysis, sensory skill, meticulousness in the preparation, organisation and performance of the tests and skill and patience to plan and execute the tests in a scientific manner.
They are the sole person responsible for selecting, training and monitoring the tasters in order to ascertain their level of aptitude. They are thus responsible for the appraisal of the tasters, which must always be objective and for which they must develop specific procedures based on tests and solid acceptance and rejection criteria. See standard COI/T.20/Doc. no. 14, “Guide for the selection, training and monitoring of skilled virgin olive oil tasters”.
Panel leaders are responsible for the performance of the panel and hence for its evaluation, of which they must give reliable, objective proof. In any case, they must demonstrate at all times that the method and tasters are under control. Periodic calibration of the panel is recommended (COI/T.20/Doc. 14/Rev 4, § 5).
They hold ultimate responsibility for keeping the records of the panel. These records must always be traceable. They must comply with the assurance and quality requirements laid down in international sensory analysis standards and ensure the anonymity of the samples at all times.
They shall be responsible for inventorying and ensuring that the apparatus and equipment needed to comply with the specifications of this method is properly cleaned and maintained and shall keep written proof thereof, as well as of the compliance with the test conditions.
They shall be in charge of the reception and storage of the samples upon their arrival at the laboratory as well as of their storage after being tested. When doing so, they shall ensure at all times that the samples remain anonymous and are properly stored, for which purpose they must develop written procedures in order to ensure that the entire process is traceable and affords guarantees.
In addition, they are responsible for preparing, coding and presenting the samples to the tasters according to an appropriate experimental design in line with pre-established protocols, as well as for assembling and statistically processing the data obtained by the tasters.
They shall be in charge of developing and drafting any other procedures that might be necessary to complement this standard and to ensure that the panel functions properly.
They must seek ways of comparing the results of the panel with those obtained by other panels undertaking the analysis of virgin olive oil in order to ascertain whether the panel is working properly.
It is the duty of the panel leader to motivate the panel members by encouraging interest, curiosity and a competitive spirit among them. To do so, they are strongly recommended to ensure a smooth two-way flow of information with the panel members by keeping them informed about all the tasks they carry out and the results obtained. In addition, they shall ensure that their opinion is not known and shall prevent possible leaders from asserting their criteria over the other tasters.
They shall summon the tasters sufficiently in advance and shall answer any queries regarding the performance of the tests, but shall refrain from suggesting any opinion to them on the sample.
8.1.1 Deputy panel head
The panel leader may, on justified grounds, be replaced by a deputy panel leader who may stand in for duties regarding the performance of the tests. This substitute must have all the necessary skills required of a panel leader.
The people acting as tasters in organoleptic tests carried out on olive oils must do so voluntarily. It is therefore advisable for candidates to submit an application in writing. Candidates shall be selected, trained and monitored by the panel leader in accordance with their skills in distinguishing between similar samples; it should be borne in mind that their accuracy will improve with training.
Tasters must act like real sensory observers, setting aside their personal tastes and solely reporting the sensations they perceive. To do so, they must always work in silence, in a relaxed, unhurried manner, paying the fullest possible sensory attention to the sample they are tasting.
Between 8 and 12 tasters are required for each test, although it is wise to keep some extra tasters in reserve to cover possible absences.
9. TEST CONDITIONS
9.1. Presentation of the sample
The oil sample for analysis shall be presented in standardised tasting glasses conforming to the standard COI/T.20/Doc. No 5 “Glass for oil tasting”.
The glass shall contain 14–16 ml of oil, or between 12.8 and 14.6 g if the samples are to be weighed, and shall be covered with a watch-glass.
Each glass shall be marked with a code made up of digits or a combination of letters and digits chosen at random. The code will be marked by means of an odourfree system.
9.2. Test and sample temperature
The oil samples intended for tasting shall be kept in the glasses at 28o C ± 2o C throughout the test. This temperature has been chosen because it makes it easier to observe organoleptic differences than at ambient temperature and because at lower temperatures the aromatic compounds peculiar to these oils volatilise poorly while higher temperatures lead to the formation of volatile compounds peculiar to heated oils. See the standard COI/T.20/Doc. No 5 “Glass for Oil Tasting” for the method which has to be used for heating the samples when in the glass.
The test room must be at a temperature between 20o and 25o C (see COI/T.20/Doc. No 6).
9.3 Test times
The morning is the best time for tasting oils. It has been proved that there are optimum perception periods as regards taste and smell during the day. Meals are preceded by a period in which olfactory–gustatory sensitivity increases, whereas afterwards this perception decreases.
However, this criterion should not be taken to the extreme where hunger may distract the tasters, thus decreasing their discriminatory capacity; therefore, it is recommended to hold the tasting sessions between 10.00 in the morning and 12 noon.
9.4. Tasters: general rules of conduct
The following recommendations apply to the conduct of the tasters during their work.
When called by the panel leader to participate in an organoleptic test, tasters should be able to attend at the time set beforehand and shall observe the following:
- They shall not smoke or drink coffee at least 30 minutes before the time set for the test.
- They must not have used any fragrance, cosmetic or soap whose smell could linger until the time of the test.
- They must use an unperfumed soap to wash their hands which they shall then rinse and dry as often as necessary to eliminate any smell.
- They shall fast at least one hour before the tasting is carried out.
- Should they feel physically unwell, and in particular if their sense of smell or taste is affected, or if they are under any psychological effect that prevents them from concentrating on their work, the tasters shall refrain from tasting and shall inform the panel leader accordingly.
- When they have complied with the above, the tasters shall take up their place in the booth allotted to them in an orderly, quiet manner.
- They shall carefully read the instructions given on the profile sheet and shall not begin to examine the sample until fully prepared for the task they have to perform (relaxed and unhurried). If any doubts should arise, they should consult the panel leader in private.
- They must remain silent while performing their tasks.
- They must keep their mobile phone switched off at all times to avoid interfering with the concentration and work of their colleagues.
10. PROCEDURE FOR THE ORGANOLEPTIC ASSESSMENT AND CLASSIFICATION OF VIRGIN OLIVE OIL
10.1. Tasting technique
10.1.1. The tasters shall pick up the glass, 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