Marco Oreggia e Laura MarinelliThe human sensory organs, subject to external stimulations, behave like real measuring instruments. In the gastronomic sector and particularly in the olive oil world, sensory analysis has been introduced quite recently. The experience acquired up to now induces us to think that expectations are great and above all correspond to those mathematical rules that base their applicability on the repetitiveness of the analytical methods. In the field of professional tasters sensory analysis was codified by the International Olive Oil Council by appropriate committees of experts called panel. But is it really possible for everyone to assess the quality and the origin of a virgin olive oil only by tasting it? The answer is positive, provided that he who approaches the tasting world follows a series of rules of conduct: the knowledge of senses, the sequence of operations to be carried out and a supporting background of experience. For neophytes we are going to describe in detail the fun damental operations to reach a good knowledge of the main features of an olive oil. Before you start tasting, it is advisable to supply yourself with green apples preferably of the “Granny Smith” variety in order to clean your mouth with a morsel before each sample.
This has a notable importance for the final assessment. There are in fact many variables that make the operation difficult for the taster. First of all the human olfactory ability is one of the most complex perception laboratories. This natural aptitude of man will never be replaced by any technology or method of analysis and the panel test is a further confirmation of this statement. In fact, until some years ago olive oil was only submitted to chemical analysis, which evidenced the regularity of the analytical parameters, but it could not assess the correct and harmonic perception of sensations. In short, although an olive oil fell into the values of acidity, peroxides and so on, it could (very often) be distasteful to sensory analysis. For this reason the legislator thought it necessary to put tasting before the chemical assessment. As to olfactive analysis, after pouring the olive oil in a glass (about 20 ml.), it should be brought to the ideal temperature for tasting (about 28 °C). The official method includes the use of appropriate instruments to heat olive oil, called thermostats; the most common method instead consists in heating the glass containing the olive oil with the hands, covering it for some minutes and shaking it delicately in order to make this process faster. Afterwards the glass is brought near the nose and you breathe in deeply through both nostrils. After a short time, the operation is repeated a second time for confirmation. The perceived aroma can immediate ly be assessed, both in case of pleasant scents due to positive characteristics, and in case of unpleasant sensations indicating the presence of defects. These positive and negative properties should be confirmed by the subsequent taste analysis.
The olive oil is brought to your oral cavity. The advisable method consists in taking it (without swallowing) by a slow and delicate suction at first, which subsequently becomes increasingly stronger. In this phase, the olive oil must be heated for a few moments to favour the evaporation of the volatile components. At the same time, you breathe in air to oxygenate the olive oil (stripping) and move it around in your mouth for some time so it can come into contact with all the taste buds. This phase is the most critical. In fact, the contemporary heating, oxygenation and rotation you can perceive qualities and defects of an olive oil in the best way. The olive oil should be spread over the whole oral cavity and especially on all the tongue, from the tip to the back, the sides and the end part. In this phase memorization and the order of perception of the sensations is fundamental. The sensations can be tactile, when they describe fluidity, consistency and viscosity or taste, which means sweet, bitter, pungent, etc., as the olive oil reaches the end part of the tongue. After that, the olive oil can be expelled. All the tactile and taste sensations, together with the olfactory and visual analysis, allow you to give a final assessment, which will have to also consider the global harmony of the sensations.
It seems strange, but it does not have a particular importance during the assessment of the olive oil quality. This is shown by the fact that in official tasting committees (panels) , the tasting glasses are purposely coloured in rusty brown or cobalt blue. The reason for this choice is due to the necessity to hide the visual characteristics, which could influence the taster’s assessment. Only later, after the taster has assessed the olfactive and taste characteristics, he will examine the visual aspects. Three different characteristics are to be assessed: limpidity, density and colour. The limpidity is a parameter which varies according to the age and the filtering processes the olive oil is submitted to, as well as to the production objectives of the factories. In fact over time non filtered oils tend to develop olfactory and taste defects, due to the presence of processing residues. The density depends instead on the territorial origin of the olive oil, whereas the colour, which varies from light golden yellow to intense green, depends on the olive variety, the harvesting period (that is the olive ripening degree) and the transformation techniques. Moreover it should be taken into account that the green colour grows less intense over the months that constitute the lifetime of an oil. the lifetime of an oil.