1. Hold a votive glass or a similarly small glass from the bottom in a cupped hand to transfer body heat to the oil. Cover the top of votive with other hand and swirl oil around bottom of the cup. (Note: The traditional color for an olive-oil tasting votive glass is blue, so your perception won’t be affected by the oil’s color. Olive oil color is not an attribute of quality, according to Elvio Olave, owner and founder of Olave. Also, because hands may alter flavor and raise temperature inconsistently, the official heating method is to place a glass covering on the votive and warm oils to the same temperature.)
2. Raise votive glass and put your nose in to take a whiff. If you smell vinegar, alcohol, or mold, something is wrong with the oil. Instead, olive oil should smell grassy and fruity.
3. Next, take a little oil into your mouth. Suck in through closed teeth to mix oil with air. Then swallow the oil. It will feel odd at first to swallow straight-up olive oil, but the step enables you to pick up on subtle tones of a given oil. Notice two things: hot and bitter tastes and fruit tones. Both are attributes of olive oil quality. They reveal the level of polyphenols (antioxidants) in the oil, as well as predict its shelf life, according to Olave. The hotter and more bitter the oil, the greater the level of polyphenols and the longer it will last.
4. After trying four to five oils, Olave’s mouth is “anesthesia,” he says, trying to explain in English. In other words, numb. To cleanse his palate, he eats a sour green apple.
Source: Elvio Olave