Unlike wine, olive oil is not normally consumed on its own, but rather as a dressing or ingredient in cooking. So why the interest in olive oil tasting? As with wine, there is a tremendous variability in product quality, and when one examines some of the (imported) products available locally, one wonders whether we are not being used as the dumping ground of the world. The situation is compounded by the lack of legislation (and even greater lack of policing) in controlling the quality of olive oil imports into S.A. 

With all this variability in quality, the olive oil consumer runs quite a risk of purchasing a second rate product, which could easily end up completely ruining the very food it is supposed to improve . A good olive oil should subtly enhance the flavours of the specific dish, not distort or overpower them. One should thus get into the habit of tasting any untried olive oil before blindly using it over one’s food. The advantages of using a good olive oil in one’s everyday cooking are legion, not only from the flavour point of view, but also because of the associated health benefits. 

Tasting olive oil is an art, but it can also be fun and worth learning. As in the case of the wine connoisseur and his wines, a certain amount of knowledge (and quite a lot of practice) is required to objectively classify olive oils according to taste. An appreciation of exactly how various factors affect the final product is essential in order to sensibly proclaim the merits of one oil above another. Such factors, including cultural techniques in growing the olives, maturity of fruit, soil type, climate, geographic latitude, cultivar mix, production methods, post-harvest storage of olives, etc., all play a part in producing high quality olive oil. 

However, we aren’t going to take ourselves too seriously today. What I know about tasting oils is what I’ve picked up slowly over the years. I haven’t attended any formal tasting courses overseas, and don’t profess to be an expert taster, but I sometimes find it amusing to watch some of our local self-appointed “experts” score exactly the same oil completely differently in double blind tastings.

Classification of Olive Oil

 Broadly speaking, international legislation divides the various classes of olive oil into (a) virgin olive oils (i.e. those which have not been refined) and (b) the chemically refined oils (called “olive oil” or “pure olive oil”). The situation is rather complicated by subdivisions within the classes, based on blends, the degree of acidity and other analytical and organoleptic parameters. A third class of oil, called (c) olive-pomace oil, is made by solvent extracting the residual oil from the presscake. This type of oil, however, cannot be called “olive oil” (or “pomace olive oil”, a term used by certain unscrupulous operators).

For the technically inclined, here’s the latest Trade Standard on Olive Oil by the IOOC (COI/T.15/NC no. 2/Rev. 6 of 5 June 1997), in which the following definitions are specified in the classification of olive oil and olive-pomace oil:

 1.                  Olive oil is the oil obtained solely from the fruit of the olive tree (Olea europaea sativa Hoffm. et Link), to the exclusion of oils obtained using solvents or re-esterification processes and of any mixture with oils of other kinds. It is marketed in accordance with the following designations and definitions:

 1.1              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 (i.e. only physical  operations, not chemical refining).

 1.1.1        Virgin olive oil fit for consumption as is (i.e. “natural”) includes: 

i)                    Extra virgin olive oil: virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 1 gram per 100 grams, and the organoleptic characteristics of which correspond to those fixed for this category (i.e. median of defects = 0;  median of fruity attribute greater than 0)

ii)                  Virgin olive oil: (the qualifier “fine” may be used at the production and wholesale stage): virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 2 grams per 100 grams and the organoleptic characteristics of which correspond to those fixed for this category (i.e. median of defects greater than  0, but less than or equal to 2,5; median of the fruity attribute greater than 0)

iii)                 Ordinary virgin olive oil: virgin olive oil which has a free acidity, expressed as oleic acid, of not more than 3,3 grams per 100 grams and the organoleptic characteristics of which correspond to those fixed for this category (i.e. median of defects greater than 2,5  but less than or equal to

6,0 and fruity attribute greater than 0, or where median of defects is greater than 0 but less than or equal to 6,0 and the median of fruity attribute = 0) 

1.1.2        Virgin olive oil not fit for consumption as it is, designated lampante virgin olive oil, is virgin olive oil which has a free acidity, expressed as oleic acid, of more than 3,3 grams per 100 grams and/or the organoleptic characteristics of which correspond to those fixed for this category (i.e. median of defects greater than 6,0). Such olive oil is intended for refining or for technical purposes 

1.2              Refined olive oil is the olive oil obtained from virgin olive oils by refining methods which do not lead to alterations in the initial glyceridic structure 

1.3              Olive oil is the oil consisting of a blend of refined olive oil and virgin olive oil fit for consumption as it is (normally ordinary virgin olive oil) 

2.                  Olive-pomace oil is the oil obtained by treating olive pomace with solvents, to the exclusion of oils obtained by re-esterification processes and of any mixture with oils of other kinds. It is marketed in accordance with the following designations and definitions: 

2.1              Crude olive-pomace oil is olive-pomace oil intended for refining with a view to its use in food for human consumption, or intended for technical purposes 

2.2              Refined olive-pomace oil is the oil obtained from crude olive-pomace oil by refining methods which do not lead to alterations in the initial glyceridic structure 

2.3              Olive-pomace oil is the oil comprising the blend of refined olive-pomace oil and virgin olive oil fit for consumption as it is (usually ordinary virgin olive oil). In no case shall this blend be called “olive oil” 

Factors affecting the quality of olive oil 

In the major olive oil producing countries of the Mediterranean, adequate control of olive fruit quality is impossible, due to the massive scale of operation. At present over 50% of the olive oil produced in these countries has high acidity and poor organoleptic 

characteristics, and is unsuitable for human consumption unless refined. Extra virgin oil accounts for barely 10% of the oil produced in many of these countries. South Africa, in  contrast, produces a very high proportion of the extra virgin quality, due to the small scale of the local industry, and the much tighter control of fruit quality. 

The following factors play a role in the quality of olive oil produced: 

-         Health of fruit (degree of pest and disease infestation)

-         Method and period of post-harvest fruit storage

-         Oil extraction system ( including extraction temperatures)

-         Method and period of oil storage prior to packing

-         Cultivar of olive

-         Climate (latitude of production area)

-         Cultural techniques (irrigation, drainage, pesticide residues, etc.)

-         Maturity of fruit (time of harvesting)

Any weak link in the chain from the fruit on the tree to the oil in the final retail pack will impact upon the quality of the oil. 

The above factors affect both the quality and keeping quality of olive oils by altering one or more of the following chemical components or indices of the oil: 

-         Free fatty acidity  (the degree of chemical breakdown of the triacylglycerols)

-         Peroxide value  (the degree of peroxidation of the oil)

-         Antioxidant content (the content of polyphenols and tocopherols)

-         Spectrophotometric constants  (mainly UV extinction coefficient at 270nm)

-         Fatty acid profile of triacylglycerols  (content of oleic, palmitic, linoleic, etc.)

-         Pigment content  (chlorophylls and carotenoids)

-         Aroma compounds  (alcohols, aldehydes, ketones, esters,  phenols, terpenes)

-         Mono- and diacylglycerol content  (partially formed triacylglycerols)

-         Sterol content  (beta-sitosterol, campesterol, stigmasterol, etc.) 

The delicate flavour of quality extra virgin olive oil is related to the presence of a large number of chemical compounds. These flavour compounds comprise aliphatic and aromatic hydrocarbons, aliphatic and triterpenic alcohols, aldehydes, ketones, esters, furan and thiophene derivatives. Over 100 such compounds have been identified which,as a whole, contribute to the distinctive organoleptic characteristics which make extra virgin olive oil so select. These aroma compounds form part of the unsaponifiable fraction, which makes up about 1% of the oil. 

These tastes and fragrances derive from compounds like hexanal (green, grassy), trans-2-hexenal (green, bitter), 1-hexanol and 3-methylbutan-1-ol, which are the major volatile compounds of olive oil. Many of these flavour compounds decompose if temperatures during milling exceed 30°C. Thus the importance of  “cold pressing”. 

Tastes and fragrances regarded as defective include the following so-called negative attributes: 

Tasting the oils 

Now that we have learned something about the various factors that influence the aroma, flavour and mouthfeel of olive oil, we can try our hand (tongue) at a few samples. All the oils chosen for our test are labeled as “extra virgin”. As we have seen, extra virgin oil is a completely natural and nutritious product (no refining or blending with refined oil is permitted) and stands apart from the “industrial” oils obtained by such refining. Remember that the refining of olive oil removes or destroys almost all of the specific characteristics we are looking for in a good oil. The delicate flavour compounds, the natural antioxidants, vitamins and pigments are completely denatured during refining, so it makes no sense to include this class of oil in our sample.

Certain obvious  precautions need to be taken before tasting the oils: 

-         ideally limit the number of samples to a maximum of about 3 or 4 per sitting. This is because one’s mouth becomes sensitized to especially the peppery and bitter tastes (not to mention off-flavours!). Also, it is much more difficult to cleanse one’s mouth completely between samples than in the case of wine

-         screen the oils by their aroma to decide the order in which they should be tasted: the milder oils first, the more intense oils last. An initial strong and overpowering oil can cause all subsequent oils to taste stronger than they really are

-         avoid the use of perfumes, deodorants, perfumed soaps and lipstick, and don’t smoke, eat sweets or drink coffee within 30 minutes before or during the tasting. Health and cleanliness of hands, and mouth are obviously essential

-         taste the oils in a  clean, light and airy locality, using separate tasting glasses for each sample 

The initial screening is done by pouring about a tablespoon of each oil into separate small tasting glasses. Taking one at a time, rotate the glass to wet the sides fully. Warm the sides of the glass with the palms of your hands to liberate the volatile aromas. Bring the oil as closely as possible to your nose and inhale slowly and deeply two or three times in succession. Note the sensations with reference to the positive and negative attributes referred to previously. If necessary, repeat after about a minute. Note your findings. 

The actual tasting can be done in one of two ways: with the oil spread on unsalted white bread, or directly from tasting glasses. Either way, taste the milder smelling oils first. 

 When using tasting glasses, take a small sip of approximately 2 to 3 ml. It is very important to distribute the oil throughout the whole of the mouth cavity, because the perception of the four primary tastes (sweet, salty, acid and bitter) varies in intensity depending on the area of the tongue, palate and throat. With your lips semi-closed, inhale rapidly two or three times in succession to atomise the oil in your mouth. The air, mixed with the oil, sprays onto your tongue and palate. Memorize the flavours, then spit the oil out. If necessary, repeat the tasting, but only after you’ve rinsed your mouth with clean water. It may help to chew a slice of apple between samples, obviously rinsing again. The stronger the flavour of the oil, the longer you’ll need to wait before the next tasting. Any oils with obvious defects should be tasted last. Note your findings with reference to the previously mentioned positive and negative attributes. A well-made reasonably fresh oil should exhibit firstly a definite olive-fruity note, followed by pungent, green and bitter (and other desirable) notes, normally in decreasing strength. No negative attributes or defects should be present. 

For an oil to be classified as extra virgin (or virgin) in terms of IOOC legislation, it is necessary for it to clearly exhibit this “olive-fruity” note. 

IOOC accredited taste panels operate in various participating producer countries with the specific task of classifying virgin olive oils according to IOOC organoleptic specifications. This is rather different to the ranking and rating of similar oils from within the same place of production, as done by various tasting clubs and associations. 

The IOOC profile sheet incorporates a continuous scale for measuring the various intensities of attributes. Panel members score the perceived intensities by marking the straight line alongside each particular attribute at exactly that point judged to correspond to the specific intensity of that attribute. Fully left represents zero units of intensity, and fully right represents a maximum intensity of 10 units. This continuous scale is supposed to facilitate statistical processing of results and the calculation of median scores, used to aid in classifying the oil as extra virgin, virgin, or ordinary virgin.