You’d be hard-pressed to find an ingredient that is more versatile in the kitchen than olive oil. But how long does olive oil last before it turns from liquid gold to rancid?
20 years ago, archaeologists in the prehistoric settlement of Castelleccio, Sicily, found an ancient dump.
But this wasn’t just any garbage pit. It was a pile of ancient Roman clay olive oil containers. The trace of olive oil recovered there dated back to 2,000 BC, and is the oldest in the world.
“Contrary to wine, which responds well to aging, olive oil is best used when it’s young and fresh, and at the height of its nutritional value,” said Astrid Liakou, an expert certified olive oil sommelier.
You certainly don’t own ancient storage containers full of olive oil — but you may have an old jug of oil that you were once gifted and seemingly has lived in the back of your cabinet since Roman times. But how can you tell if it’s still edible?
How Long Does Olive Oil Last?
On average, the typical bottle of olive oil you purchased from your local supermarket or gourmet store will last from two to four years. But olive oils are all unique, and their shelf lives vary depending on their quality, where and when they were harvested, how they’re pressed, and how they’re stored.
Check the Harvest and “Best By” Dates
Your best bet for determining the lifespan of that special bottle of olive oil you purchased on vacation in Barcelona last year (or, admit it, got on sale at Trader Joe’s) is evaluating the harvest and expiration dates. Most reputable brands will include these dates somewhere on the packaging.
The harvest date is a better indicator than the bottling date, which some producers also include, because olives are only picked to make oil once a year. There might be quite some time before the oil is actually bottled, distributed and put on the store shelf. Olives are usually harvested in the fall, so the freshest olive oil would have a harvest date from the most recent autumn.
Recommendations for how long a particular oil will stay fresh vary by manufacturer. Many producers will list a “best by” date around two years from the harvest date, but oils can begin to oxidize within a year of harvest. Bertolli’s estimate is more conservative, at 14 months. A good rule of thumb might be the Italian government’s guideline, which is 18 months from harvest. Bear in mind that extra virgin olive oil (EVOO) goes bad more quickly than lesser oils, and that fresh olive oil is always going to be better than aged oil.
While the harvest date is a great guideline, the best way to tell whether your oil has gone off is your own sense of smell and taste. Learning how and why olive oil goes bad — and training your palate to understand oil quality — can help you become a more discerning consumer, and a chef’s-kiss-worthy cook.
Learn a Little Chemistry
Olive oil goes bad thanks to the same chemicals that make it so healthy to begin with: antioxidants.
Antioxidants include components like vitamin E and polyphenols, and they help us by scavenging free radicals. That means they process oxygen molecules that have broken down into single atoms, which, if unchecked, can cause damage to the body’s cells.
While they can help us stay healthy, and hopefully live longer, antioxidants themselves don’t live forever. After a period of time oxidation will begin, meaning the oil will break down. This happens more rapidly when they’re exposed to light and air, which is why organizations like the California Olive Oil Council recommend choosing oils that are packaged in tin or a dark glass bottle.
Trust Your Taste
While harvest and best-by dates are the most obvious metric, the surefire technique for determining whether your olive oil has gone bad is also the most fun: Taste it!
“Good olive oil should taste and smell fresh, like a freshly-picked, still-green olive rubbed between your hands, or similar to a green almond picked fresh from the tree,” Liakou said.
Most people who don’t live near Italian or California olive ranches, of course, have never smelled a fresh olive. In that case, Liakou recommends looking for the “fresh, slightly green scent of a newly sprouted twig on an apple tree in the spring.”
Quality olive oils aren’t just fruity in taste. They may also have bitter or spicy notes, leaving a prickle at the back of your throat. This isn’t a sign that the oil has gone bad — it’s just a natural flavor variation.
Color isn’t necessarily an indication of freshness or quality. Variation in color, from golden to greenish, is natural.
How Do You Know If Olive Oil Has Gone Bad?
Olive oil that has gone bad will smell and taste — you guessed it — bad. According to Liakou, if your bottle of oil smells like the black olives left out too long on a table of appetizers last Thanksgiving, you’ve likely got a rancid bottle. Other aromas that some have used to describe the smell of bad olive oil: crayons, putty and Elmer’s glue.
The rancid taste of bad oil is different, by the way, from a spicy, tingly or slightly sharp oil. A high-quality oil can sizzle on the palate, like a dash of pepper on the back of your throat. In contrast, olive oil that has gone rancid will carry notes more reminiscent of French fries kept too long in the deep fryer.
There’s no single taste that’s associated with rancidity. Your best bet in figuring out when your olive oil has gone bad is knowing what it tastes like when it’s good. So cook with that gourmet bottle as soon as you receive it at your housewarming party, or head to a fancy olive oil store and help yourself to free samples. That’s not freeloading; it’s research.
Is It Okay To Use Expired Olive Oil?
Technically, yes. But does olive oil go bad? Also, yes. Here’s the explanation. You can use expired olive oil and it shouldn’t make you sick or cause serious side effects. However, rancid olive oil will lack in nutritional value and health benefits, compared to a freshly acquired bottle. It will also cause whatever dish you’re making to have a weird and unappealing taste. If flavor is important to you, it’s probably best not to use olive oil that has gone bad.
How to Store Olive Oil
Olive oil should be stored in an airtight container that can shield it from sunlight, such as dark glass or pottery. Keeping it in a dark place like a pantry or cabinet is also recommended.
“The archenemies of olive oil are exposure to air, light, too high or low temperatures and strong odors that it can pick up,” Liakou said.
It’s important to keep olive oils away from heat sources like stoves or ovens (so don’t store it in the shelf right over your cooktop). It’s best stored in a cool place, or in a cabinet at room temperature. Because olive oil generally goes rancid after one-to-two years, buy accordingly.
If you have an Italian grandmother or come from a Mediterranean country, you might have grown up with vats of olive oil bought either directly from the grower or from the grocery store, kept in a cabinet and then regularly transferred to a container for liberal use in cooking.
If you foresee using much less oil than a Mediterranean granny, however, it’s better to buy smaller bottles when you need them. It’s expensive to stock up on large ones and end up throwing them away.
“If you are unsure about whether you can use up your bottle in say 2-3 months, opt for buying a smaller one to start with and move to larger bottles when you increase your consumption,” said Liakou.
How Can I Pick The Best Quality Olive Oil?
Another way to extend the life of your oil, and to make sure you’re having the best taste experience, is to choose better-quality oils in the first place. While price isn’t always indicative of quality, the best oils are more expensive than olive oils adulterated with other kinds of vegetable oils, like canola oil. A 750 mL bottle of very high quality oil can cost upwards of $50.
You can easily access more affordable extra virgin oils at your local grocery store or online, where three-liter tins can go for $20 or $30. But price isn’t the only indication, or even the primary indication, of an oil’s quality. Instead, you can look for packaging indications that an oil is fresh and made well.
The quality of an oil depends largely on the conditions of the olives as they are picked, stored and transported. According to Liakou, good oil should be pressed from slightly unripe olives within a day of harvest. If the olives are bruised or not very fresh, the resulting oil will oxidize rapidly, leading to a shorter shelf life and a musty or rancid smell and taste.
Grocery store conditions matter, too. Olive oil should be stored in an opaque container to prevent light from oxidizing the oil, so avoid clear bottles that let you see how beautiful the olive oil appears. Look for dark glass or tin containers instead.
Look For an ‘Extra Virgin’ Label
Extra virgin certification, the highest quality grade an oil can receive, indicates that high standards of production have been met. According to the California Olive Oil Council, extra virgin labeling means that the oil has been tested in a lab; EVOO must be unrefined, cannot contain chemical additives, and cannot have been altered by temperature.
Besides the chemical testing, oils are certified extra virgin through the most sensitive instrument: a panel of olive oil sommeliers who taste the product to make sure it’s of superior quality with no defects in taste or odor.
Professional and governmental bodies — from the European Union’s olive oil marketing standards and Protected Geographical Indication, to the California Olive Oil Council’s Seal Certification Program — offer further assurance to consumers.
Why would you pay extra for extra virgin olive oil? In short, it’s the purest and cleanest-tasting type of olive oil you can buy. Just be aware that it has a lower smoke point than other oils, so it’s not the best choice for sautéing or baking. Savor its goodness in dressings or dips instead. (There’s only way to eat a great piece of bread, of course: dipping it in extra virgin olive oil.)
Beware of Olive Oil Fraud
There have been many recent reports of olive oil adulteration, from adulterated oil being sold under the “extra virgin” label, to the mafia profiting from olive oil fraud. In fact, olive oil fraud is as old as civilization itself: The world’s first written mention of olive oil, found on a 24th century BC Syrian tablet, concerns detection of fraudulent olive oil.
Nonetheless, some research suggests the problem may not be as widespread as alarmists might have you think. In a 2015 study, the FDA found that only three of 88 tested olive oils had been adulterated. Still, researchers are hard at work developing affordable, convenient ways to test olive oil for purity, including near-infrared spectroscopy that can test the purity of large quantities of oil in a relatively short amount of time.
The Final Taste Test: Educate Your Palate
The best way to tell whether your olive oil is of good quality or has gone rancid isn’t fancy machines, or even the labeling on the bottle. It’s your own sense of taste and smell. While the idea of “educating your palate” may sound unattainably posh, the most accessible and fun way to learn about food is by eating it.
Try free samples at gourmet stores, hint to your loved ones that a fancier-than-usual bottle is exactly what you want for your next birthday, and sprinkle your food with as much of that good, golden stuff as you want. It’s healthy and delicious – and the more you eat it, the more educated you’ll be.
Download Our Free Guide to Sustainable Living.
From reducing waste to recycling and upcycling, our e-book shows simple ways to make choices you can feel good about.