Extra Virgin Olive Oil has long been one of the most adulterated food products in the world. Today's market is seeing a lot of oils blended with the previous years' crop, mystery cocktails of different sources, and just rancid, or defective oils, which can be bad for you. Regulations are tightening up a bit around the world but the best way to figure out if your olive oil is a true, pure, Extra Virgin Olive Oil is to taste it (also be sure to check harvest dates and make sure it's source from one place). You don't have to be a professional olive oil sommelier or a super sniffer to smell and taste freshness. A proper sensory analysis of the oil you have at home only takes a few steps and can be guided by a few simple guidelines.
Pour a tablespoon or two of olive oil in to a cup - a shot glass, stemless wineglass or small plastic cup will work, as long as you can get your nose into it. Try not to pay too much attention to the color of the oil, as it can unconsciously affect judgement. In certified tasting panels, tasters will pour oil in to blue tinted glasses.
Place the cup in your hand with another hand over the top and gently swirl. The bottom hand slightly warms the oil to help release the aromas as you swirl, and the top hand traps them in for when we're ready to take a whiff. Make sure your hands don't smell like lotion, perfume or soap.
Remove your hand and bring the cup to your nose. Inhale deeply with your nose. What you smell should remind you of something green or something fresh. Feel free to smell the oil a few times before going in for a sip. Really think about what you're smelling, as a good oil should have a fruity aroma that matches what you'll experience on the palate.
Slurp! Take a sip of oil while also "sipping" in some air, effectively spraying the oil across your palate. Take note of the bitterness of the oil, which is generally felt on the sides of the palate. The retro-nasal aroma will give you lingering flavor profiles to (hopefully) enjoy. Think of how the oil feels in your mouth - does it feel light and clean or heavy and greasy? Lastly, take note of how the oil feels in the back of the throat after you've swallowed it. A good oil will leave a tingly "pepperiness" or pungency which might make you want to cough. If you're tasting more than one oil, cleanse the palate with green apple or water. Be sure to document the fruitiness (the smell), the bitterness, and the pungency to compare notes.
The following descriptors will help you and your friends explore your olive oil tasting a bit deeper. Most green things that exist in the natural world can be used as a descriptor. Again, tasting extra virgin olive oil is simple; it should remind you of something green/fresh, leave your mouth feeling clean, and have a pleasant aroma.