How To Tell If Olive Oil Is Rancid + Uses for Rancid Olive Oil

Rancid Olive Oil Image

You were about to use your olive oil as an ingredient for your dinner recipe. Then you opened the bottle and ugh! It smells absolutely horrible. You think your olive oil has gone rancid, but you’re not sure. How can you find out?

To tell if your olive oil is rancid, do the following:

  • Don’t sniff straight from the bottle, but rather, put some olive oil in a container like a cup
  • Smell the oil for an odor that’s like a combination of glue and fermented fruit
  • Drink a small amount; if has no taste or a flavor like old peanuts and crayons, it’s rancid
  • Feel for greasiness as you drink, as that’s another sign of rancidity
  • Look at the expiration date

In this informative guide, we will elaborate on the above points as well as explain everything you’d ever want to know about olive oil rancidity. From why olive oil goes rancid to whether you can do anything with it at that point, keep reading!

Understanding Rancidification

Before we can talk more about the points we mentioned in the intro, we want to first make sure you understand what rancidity is in olive oil. Rancidification isn’t just another name for expired food. It’s its own process that can occur to many foods, olive oil included. Even extra virgin olive oil isn’t even safe from rancidification.

Okay, so what’s rancidification anyway? It’s when oils and fats hydrolyze or oxidize, but not always completely. The hydrolyzation and oxidization occur because the food got an excess of moisture, light, air, and even bacteria. In layman’s terms, your food now smells and tastes horrible. If your food had vitamins and other nutrients in it, it’s possible for the quality of these to deplete through rancidification.

Rancidification has three forms or pathways. These are microbial, oxidative, or hydrolytic rancidity. Let’s go over these three forms in more detail now.

Microbial Rancidification

With microbial rancidification, molds and other bacteria begin dissolving fat through lipases and other enzymes. This is defined as water-dependent. By adding vitamin E and antioxidants to food as well as pasteurizing certain products, it’s possible to avoid microbial rancidification, as the bacteria get destroyed.

Oxidative Rancidification

Next, there’s oxidative rancidification. As we mentioned before, oxygen can cause this rancidity. Unsaturated fatty acids and their double bonds break down due to molecular oxygen reactions with free radicals. The radicals make ketones and aldehydes, which begin the rancidification. By using antioxidants in foods as well as storing them in airtight containers, you can prevent oxidative rancidification. That’s often all that works, as some food will very slowly become rancid even when frozen.

Hydrolytic Rancidification

The third form of rancidification is hydrolytic. Free fatty acids come from the hydrolyzation of triglycerides. When water and lipids meet, glycerol and free fatty acids form, especially short-chain fatty acids. Some of these acids, including butyric acid, have a smell that’s quite unappealing.

How Can You Tell If Olive Oil Is Rancid?

Okay, so now you understand that rancidification is about more than just a food going bad. It’s a chemical process that affects food down to its very molecular level. All that being said, let’s dig deeper into the tests you can perform at home to determine if your olive oil has gone rancid.

Pour Olive Oil into a Container and Sniff

When you open a bottle of olive oil and stick your nose into the opening, you don’t really get a good sense for the true smell. You might have notes of spice or pepper as you sniff. To you, this might not seem right, but those scents aren’t bad. Instead, they’re an indicator of a high-quality olive oil, most often of the extra virgin variety.

That’s why we recommend you take some olive oil from the affected bottle and pour it into a container like a cup or small bowl. Thenyou can lean your nose in close and take a sniff or two. If your olive oil has gone rancid, it will have a pretty distinct odor that’s difficult to miss.

As you remember from the last section, with hydrolytic rancidification, the breakdown of fats produces short-chain fatty acids responsible for that terrible smell. Some olive oil lovers describe it as excessively sweet yet almost like Elmer’s glue. Others say it’s more like fermented fruit, so still sweet.

Now, if it’s extra virgin olive oil we’re talking about here, that will have a naturally sweet scent to begin with. Thus, it’s a bit harder to ascertain whether this oil has gone bad, but trust us when we say that when you know, you know.

If you’re still not sure, don’t despair. Luckily, there’s another way to check for olive oil rancidity that’s pretty much foolproof.

Consider Tasting the Oil

That method is to consume some of the olive oil for yourself. Yes, this is kind of gross, but it’s definitive proof that your olive oil has become rancid. Again, we don’t recommend taking a swig out of the bottle. Instead, you want to pour some into a cup. Let that cup get to room temperature, holding it to help warm it if you want to speed up the process.

You don’t want to drink a whole lot here, about a tablespoon’s worth. If you have a large kitchen spoon in your utensil drawer, it’s that much olive oil.

Now, what should it taste like? That’s where the crowd gets divided. Some olive oil fans mention the taste is like old peanuts or even putty or crayons. Others say it has no taste at all.

The best way to truly experience the taste, as bad as it could be, is to slurp. No, it’s not appealing, but do it anyway. Take your time as you slurp and make sure you don’t exhale. You don’t want to swallow right away either. Instead, slurp and then release your breath. Then swallow. By that point, you get a full depth of flavor…well, if the olive oil has flavor. Not all rancid oil does.

Sometimes you might notice you get a mouthful of sediment. Sorry about that. This sediment isn’t a sign your olive oil has become rancid. In fact, sediment is normal, especially if you buy your olive oil unfiltered. Olive pieces comprise the sediment, so it’s not as disgusting as it sounds. However, if you’re used to liquid smooth olive oil and you’re already concerned about rancidity, some sediment can definitely be off-putting.

If by chance tasting the olive oil still doesn’t clue you in on whether it’s rancid, then stop for a moment and think about how it felt sitting in your mouth and going down your throat. Was it greasy? That’s how a lot of people describe the mouthfeel when tasting rancid olive oil. If you felt this, too, that’s about as clear a sign as any that your olive oil has unfortunately become rancid.

Check the Expiration Date

You also want to inspect your bottle, looking for a best by or expiration date. You generally get about two years of use with olive oil. If you’ve noticed the above unpleasant odor and taste andyour olive oil expired two or three years ago, then it’s way past its prime.

Is the Expiration Date Always Accurate?

We want to talk about the expiration date a little more. These dates can cause a great deal of confusion for consumers as people question their accuracy. That’s because there’s a variety of dates printed on food products, and not all of them mean the same thing.

For instance, the sell by date is just that. It’s how long the retailer recommends the product sits on store shelves. It’s not the expiration date, just when you should buy it.

The use by, best by, or expiration date doesrefer to the period in which your food is freshest. It doesn’t mean the food will automatically expire on that day or even the next, just that its freshness will begin degrading from there. You can generally use your common sense to tell when a food has gone bad. If it’s milk, it will curdle and reek. Bread goes moldy and olive oil becomes rancid.

With olive oil, it’s best to follow its harvest date for freshness. This date lets you know when the olives got harvested and then milled. Unfortunately, not every brand of olive oil shares this information, leaving you with only the expiration date.

Is Your Olive Oil Rancid or Defective?

Did you know you could face yet another issue with your olive oil besides rancidification? It could also be defective. An olive oil defect occurs during the production process and unfortunately does affect flavor. The olive oil isn’t rancid, and it’s not even bad, per se. There’s just something wrong with it that makes it not so pleasant to use.

For example, there’s olive oil mustiness. If some moldy olives slipped into the olive oil production, then your oil will decidedly taste quite strange. It’ll have a taste like a musty basement, so it’s not nice at all. Also, manufacturers might accidentally ferment the olive oil incorrectly. That could give the oil a vinegary taste that some people liken to nail polish.

Another big defect that sometimes comes up is fustiness. The olives sadly wait too long after harvesting and get funky. A fusty olive oil has a smell and taste that’s hard to pick up on unless you’ve had a lot of good olive oil before. Then you can tell there’s something in the flavor that shouldn’t be.

Can You Still Cook with Rancid Olive Oil?

What if you spent good money on a bottle of olive oil but kind of forgot it was there until now and it’s rancid? There’s got to be a way to turn things around and make the oil more edible, right? If only that were true.

Once your olive oil becomes rancid, that’s it, it’s over. You can’t make it un-rancid. Freezing it or storing it somewhere dark won’t make it better. You have to throw out the bottle. Rancid olive oil has no place in dishes or recipes. Even if you parted with a lot of cash for the bottle, chalk it up to a lesson learned and take better care of your olive oil in the future.

You always want to keep your olive oil in a dark, cool environment like a cabinet or drawer. Don’t refrigerate it either. If it develops too much condensation, then the flavor could go downhill. Never freeze the bottle, as it could potentially explode and it won’t help the oil stay fresher longer.

Related Questions

Is rancid olive oil bad for you?

While olive oil has a host of health benefits, that only applies to oil that isn’t rancid. If yours has become rancid, then you need to throw it away, as we said. Consuming it is bad for you, as you could get ill for your troubles.

Rancid olive oil lacks antioxidants as well, so there are truly no health reasons to eat olive oil that has gone bad.

How long does it take for olive oil to turn rancid?

As mentioned, most olive oil has an expiration date good for two years. You could get several more months out of it from there, but the rancidification process will occur sooner than later. Even if your olive oil hasn’t become rancid after two years, it’s still within your best interest to consider buying a new bottle anyway. You don’t want to ever have to smell or taste rancid olive oil if you can help it!

Does rancid olive oil have any use?

Some people advocate for sparing your rancid olive oil from the trash bin and repurposing it for non-edible purposes. These include:

  • Using it for animal feed or in soap
  • As a finish for wicker or rattan furniture
  • For cleaning and preserving your leather surfaces
  • For polishing and conditioning furniture
  • As oil for lamps
  • As a preventer of rust and as a lubricant

Now, if you can stand the smell, then by all means, try using rancid olive oil for the above jobs. To each his or her own!

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