How to Test Olive Oil

Reviewed by Marrow Private Chefs

Last Updated: December 31, 2024

Conducting the Fridge Test

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Trying the Oil Lamp Test

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Video

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Tips

If you’re unsure whether a certain brand of olive oil really is pure, there are a few ways of figuring it out. Unfortunately, lots of brands of olive oil are often tempered with. It's common to find olive oils that are diluted with lighter, cheaper oils. ^{[1]
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Research source} Luckily, there are ways of testing the purity of olive oil that are actually much simpler than you'd think.

Method 1

Method 1 of 2:

Conducting the Fridge Test

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Make sure you’re using a very clean jar, as you won’t want anything to mess with the test. Then go ahead and seal the jar shut.
This gives the olive oil enough time to solidify. You'll want to leave your olive oil as uninterrupted as possible, so avoid moving it around by placing it in a back corner of your fridge.

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Check to see if the oil is solid or liquid. After the 24 hours has passed, you should be able to tell which state the olive oil is in. At this point you can take it out of the fridge.
- If the oil turned into a solid, it's pure olive oil. This means its monounsaturated (containing only one carbon bond).^{[2]
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- If the oil has remained as a liquid, it's not pure olive oil. That would mean that it’s polyunsaturated (containing several carbon bonds).^{[3]
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Method 2

Method 2 of 2:

Trying the Oil Lamp Test

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Coat a wick in olive oil. Olive oil should be able to keep a wick lit if it is indeed extra-virgin. A pure olive oil should also burn smokeless.^{[4]
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- You may want to do this outside in anticipation of possible smoke.
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Put the wick in a glass container. This test is better and safer when done in a container rather than holding the wick in your hand. The more shallow the container is the better you’ll be able to light the wick.^{[5]
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- Use flame retardant gloves as well. Take care not to burn yourself.
If the wick doesn’t remain on fire then you'll know that you're using fake olive oil. If the wick is lit but it’s also producing smoke, you can assume that it's fake olive oil.^{[6]
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Tips

Avoid olive oils that don't say "extra-virgin" on the label.^{[7]
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Research source} Finding “pure” on the label isn’t as much of a guarantee.

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Look for the name of a farm or for a harvest date. It's always better the more specific details there about how or where the olive oil was produced.^{[8]
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You can find organic, extra-virgin olive oil at most organic markets. It can easily be found online as well, just be sure to use the keywords "extra-virgin olive oil."

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