I think that many of us have experienced that olive oil has an unusual behavior. Why sometimes does it become bitter when it’s blended? Well there are many answers out there about the quality being secondary or because the heat, caused from the high speed spinning blades of the food processor or blender, turns the oil bitter. All these are myths and speculations, not facts.
The only explanation that is a scientific explanation and makes sense, is the one that came from Cook’s Illustrated. I have read a lot of great information about them and in my opinion their kitchen is run like a laboratory. That makes them very credible.
Cooks Illustrated states that extra virgin olive oil is the only oil that can become bitter easily. It is because its content of poly-phenols (these are the cancer fighting compounds) is very high and they are coated with fatty acids. Under normal conditions these fatty acids, prevent the poly-phenols from coming in contact with a wet environment. We know that oil and water don’t mix.
The poly-phenols when are broken into droplets in an emulsion, fall into the solution and then their bitter taste becomes noticeable. But when the emulsion is blended lightly, the bitterness is not noticeable. Because blenders and food processors break the droplets into smaller pieces, the poly-phenols get scattered and usually ruin a good recipe with bitterness.
The best way to avoid this problem is to avoid using extra virgin. You can use a pure olive oil or a vegetable oil.
For me not using extra virgin olive oil is out of the question. I wouldn’t replace it with anything else. My personal answer to this problem is that you can use a whisk and hand whisk your emulsion, instead of using a blender or food processor. There is always a way to choose to do things, so they turn out the best possible way.
Well, this way you can beat olive oil in its own game.
Olive Oil And Its Bitter Truth