Rancidity is a process that only occurs in oils or foods that contain fats and oils. Rancid oils have a characteristic rank smell or taste, which is a result of chemical decomposition. This process not only makes the oil unpalatable, it deprives it of antioxidant polyphenol, the crux of its nutritional value.

Here's how you can detect a rancid oil: Rancidity is hard to detect but with these few steps, you can do so using your sense of smell and taste:

1. The Odor Test:

Pour a small amount of the olive oil into a cup so you can get a good whiff. If rancid, the olive oil will smell of an unpleasant sweetness much like fermented or rotten fruit. Some have also likened the smell to that like Elmer's glue.

2. The Taste Test:

This step is required because numerous EVOOs have a naturally sweet smell that the average person may mistake as rancidity.

Firstly, warm the cup in your hands to bring it to room temperature. Slurp about a "tablespoon of oil into your mouth without swallowing or exhaling, keep slurping, breathe out, and if it's completely tasteless, it's rancid."

If your EVOO does happen to be rancid, you have no choice, but to discard it. Therefore, it is crucial that you store them properly. Here are some tips that'll help you do that:

  • Check the harvest date on the bottle when shopping. Buy the newest bottle available because the shelf life of EVOO is about two years after harvest, even with proper storage.
  • Go for olive oils packaged in dark glass or metal tins, they protect the oil from light, and so make it last longer.
  • Store your olive oil in a cool, dry, dark place.

Good luck!