Olive oil is a popular cooking oil that is made by crushing whole olives. It has many culinary uses and potential health benefits. However, some people wonder if olive oil can go bad if it is left uncovered or exposed to air.
Quick answers
- Yes, olive oil can go bad if left uncovered and exposed to air, light, and/or heat.
- Olive oil contains delicate fats that are sensitive to oxidation, which causes oil to go rancid over time.
- Storing olive oil in a cool, dark place and keeping it sealed can help extend its shelf life.
- Signs that olive oil has gone bad include changes in color, smell, and taste.
- Rancid olive oil should be discarded and not consumed.
Does olive oil need to be refrigerated?
In general, olive oil does not need to be refrigerated. Cold temperatures can actually cause olive oil to become cloudy and solidify. The ideal storage temperature for olive oil is 57-60°F.
However, refrigerating olive oil is not necessarily harmful. If stored properly in an airtight container, refrigeration can help slow down the oxidation process and extend shelf life. Just be sure to allow refrigerated olive oil to come to room temperature before use.
Why does olive oil go bad if left uncovered?
There are a few reasons why olive oil can go bad if it is left uncovered:
- Oxidation: When exposed to oxygen, olive oil undergoes an oxidation process that causes it to go rancid over time. Leaving olive oil uncovered allows more air contact and accelerates oxidation.
- Light exposure: Olive oil is photosensitive, meaning exposure to light can degrade the oil and nutrients over time. Sunlight and other UV sources can speed up spoilage.
- Heat: High temperatures also accelerate the oxidation rate of olive oil. Leaving olive oil uncovered near a heat source like the stove can shorten its shelf life.
The delicate fatty acids in olive oil break down when exposed to these elements, leading to undesirable changes in taste, smell, color and nutrition. Keeping olive oil sealed in an airtight, UV-protective container helps minimize exposure and slows down spoilage.
How long does olive oil last if left uncovered?
The exact shelf life of olive oil can vary based on factors like storage methods and olive variety. But in general:
- Unopened, high quality extra virgin olive oil can last 12-24 months from the harvest date if stored properly.
- Once opened, olive oil will last 3-6 months if kept sealed and stored away from heat and light.
- If left uncovered and exposed to air, light, and heat, olive oil will go bad much faster—within 1-3 months.
Consumption frequency also impacts shelf life once a bottle is opened. Olive oil will deteriorate faster in a half-empty bottle repeatedly exposed to air versus a bottle that is used up more quickly.
How to tell if olive oil has gone bad
Watch for the following signs that your olive oil has spoiled and should be discarded:
- Change in color: Fresh olive oil is a bright greenish-yellow. As it goes bad, the color fades to a pale yellow or golden shade.
- Cloudiness: The oil will look hazy or murky rather than clear.
- Foam: Bubbles or foam accumulate on the surface.
- Unusual odor: Rancid olive oil smells stale, nutty, or waxy compared to fresh olive oil’s fruity aroma.
- Change in taste: Instead of tasting bold, bright, and peppery, rancid olive oil may taste cardboard-like, soapy, or bitter.
If you notice any of these characteristics, safely dispose of the olive oil. Do not try to salvage or consume rancid olive oil.
How to store olive oil properly
Follow these tips to help maximize the shelf life of your olive oil:
- Purchase smaller bottles: Opt for 375mL or 500mL bottles to minimize air exposure once opened. Or buy olive oil in tin or foil pouches.
- Keep sealed when not in use: Always replace the cap or lid securely after using to block oxygen.
- Store in a cool, dark place: Keep olive oil away from heat and light sources like stoves, windowsills, and lamps.
- Use within 3-6 months: Try to use up opened bottles within 3-6 months.
- Check the harvest date: For the best flavor and shelf life, look for bottles with a harvest date less than 18 months ago.
- Buy from reputable sources: Get olive oil from producers that harvest, store, bottle, and ship oil properly.
Glass and tin containers are ideal for blocking light exposure. Storage temperatures between 57-60°F are optimal to slow oxidation while avoiding cloudiness.
Can you restore spoiled olive oil?
Unfortunately, there is no way to reverse olive oil spoilage. The oxidation process cannot be undone. Attempting to “refresh” rancid olive oil by filtering, freezing, or adding ingredients will not restore quality or make it safe to consume.
Some ways people try to revive spoiled olive oil include:
- Refrigerating or freezing the oil
- Filtering the oil through clay, charcoal, or coffee filters
- Adding salt, citrus zest, rosemary, or oregano
While these methods may help mask some unpleasant flavors, they do not reverse the chemical breakdown of fatty acids that occurs as oil goes rancid. Olive oil that has spoiled should always be discarded.
Health risks of rancid olive oil
Consuming rancid olive oil poses some potential health risks:
- Decreased nutritional value: As olive oil deteriorates, it loses some of its beneficial vitamins, antioxidants, and healthy fats.
- Gastrointestinal distress: Spoiled olive oil can irritate the digestive tract, causing symptoms like nausea, diarrhea, vomiting, and stomach cramps.
- Negative health effects: Animal studies link oxidized fats to increased inflammation, liver damage, arterial plaques, and other adverse effects.
The main concern is that oxidation produces free radicals that can damage cells in the body. The free fatty acids and aldehydes created as olive oil goes rancid are pro-inflammatory. It’s best not to take a chance and avoid rancid olive oil entirely.
Uses for olive oil past its prime
If your olive oil is nearing the end of its prime but not completely rancid, you may wonder if you can still use it up. Here are some safe ways to use up olive oil that is just starting to degrade in quality:
- Apply to wooden cutting boards and utensils to condition and protect wood from stains and cracks.
- Use to lubricate kitchen tools and appliances, like meat grinders, juicers, and food processors.
- Mix with sugar or salt to make homemade olive oil scrubs for body exfoliation.
- Combine with baking soda and soap to make olive oil soap bars for hands and body.
- Rub onto leather goods, like shoes, purses, and furniture, to moisturize and condition.
- Use as a natural rust remover and polish for iron-based tools, metals, and cast iron.
Avoid consuming olive oil that smells, tastes, or looks off in any way. But olive oil that is nearing expiration can still be useful for non-food purposes.
Frequently asked questions
Does extra virgin olive oil go bad?
Yes, extra virgin olive oil (EVOO) does eventually go bad. EVOO is less processed than other types of olive oil, so it retains more flavor compounds and antioxidants. But this also makes it more susceptible to oxidation. Opened bottles should be used within 3-6 months.
Can you get food poisoning from rancid olive oil?
Consuming rancid olive oil is unlikely to cause food poisoning or acute illness. But the oxidation byproducts and free radicals created as olive oil spoils may irritate the digestive tract. In large amounts, rancid olive oil can potentially cause diarrhea, vomiting, and stomach pain.
Does heat affect olive oil shelf life?
Yes, heat can greatly accelerate olive oil spoilage. Leaving olive oil near heat sources like stoves or ovens causes it to oxidize faster. High temperatures break down olive oil’s fatty acids and delicate nutrients more quickly. Store olive oil away from heat for maximum shelf life.
How can you tell if olive oil is old?
Signs that olive oil is past its prime and should be discarded include:
- Pale or golden color instead of bright green-yellow
- Cloudy or murky appearance
- Bubbles on the surface
- Lack of fruitiness or peppery flavor
- Stale, waxy, or rancid smell
- Unpleasant bitter or soapy taste
An older olive oil may also feel viscous, greasy, or leave persistent oil slicks on surfaces. If in doubt, do a taste test to detect rancidity before consuming.
Should you rinse olive oil after frying?
It’s generally not necessary to rinse olive oil after frying foods. Rinsing away olive oil also washes away some of the flavor and crunchy texture it imparts during frying or sautéing. Instead, try these tips:
- Blot fried foods with paper towels to remove excess grease.
- Use an oil strainer to filter out food particles so oil can be reused.
- Allow used oil to cool completely before pouring back into the container.
- Discard oil that smells or looks heavily degraded.
But if the olive oil seems compromised in any way, rinsing it off is better than consuming rancid oil.
Conclusion
To summarize, olive oil does have the potential to go rancid if left uncovered. Exposure to oxygen, light, and heat degrades olive oil’s quality over time. Sticking to proper storage methods, buying smaller bottles, monitoring for signs of spoilage, and using opened bottles within 3-6 months can help prevent oxidation and prolong shelf life. While not a health threat, consuming rancid olive oil is not recommended. Discard any olive oil that smells or tastes unpleasant, and do not try to revive spoiled olive oil.
