Tasting like a professional
As with wine, olive oil production involves professional "tasters" who identify the oil's aromas and flavours. To confirm the "extra virgin" category, this tasting is compulsory and is carried out by an approved panel: if the oil does not score above 0 for fruitiness with no sensory defects at all, it cannot be called extra virgin.
Some mills have in-house tasters who adjust the sensory characteristics during extraction and prepare blends. Most of the positive attributes and aromas come from polyphenols; they are all the more intense when the olives are picked and milled close to veraison.
Ideally, tasting takes place in small round blue glasses covered with a watch glass (a small transparent lid). The blue colour prevents the taster from being influenced by the colour of the oil. The lid traps the aromas, which are released strongly when the taster lifts it. The oil should be at 28 °C.
Tasting is done much like wine tasting: first by smell, then by taking small sips that coat the tongue and the back of the mouth down to the throat. It is not advisable to taste more than four oils in a row. Between oils, to clear the previous one, eat a piece of apple and then rinse your mouth with water. Water alone is not enough, because oil does not dissolve in water; the apple picks up the oil molecules that cling to the inside of the mouth.
Positive attributes
- Fruity: the set of aromas characteristic of the oil, which depend on the olive variety and come from healthy, fresh fruit, green or ripe, perceived directly or retronasally.
- Bitter: a basic taste characteristic of oil obtained from green olives or olives at veraison.
- Pungent: a peppery, prickling sensation typical of oils produced early in the season, mainly from olives that are still green, felt throughout the mouth and particularly in the throat.
- Notes and aromas: the range of aroma and flavour nuances perceived during tasting. The most common fall into four groups:
- herbs and spices: cut grass, basil, thyme;
- nuts and dried fruit: green almond, toasted almond, walnut, hazelnut, fig;
- fruit: apple, tomato, banana;
- vegetables: artichoke, avocado.
Negative attributes
- Winey or vinegary: a taste reminiscent of wine or vinegar.
- Acid or sour: a sour sensation caused by excessive oxidation during production.
- Rancid: oil that has oxidised significantly since bottling.
- Frostbitten: a cooked-endive taste in oil from olives that have been frozen.
- Heated or burnt: oil that has been overheated during extraction.
- Fusty: a dense, pasty mouthfeel and a manure-like smell, caused by olives piled up too long before milling.
- Vegetable water: a defect caused by prolonged contact with fermented vegetation water.
- Pressing mats: a smell reminiscent of wet straw. Pressing mats are fibre discs used to separate water and oil; normally neutral in taste, they can ferment or oxidise and pass this defect on to the oil.
- Metallic: a taste in oil that has been in contact with metal surfaces for a long time during milling.
- Grubby: a cold-coffee smell in oil from olives heavily attacked by olive fly larvae.