Olives are a favorite addition to salad, pasta, and other fancy diner recipes. If you’ve ever thrown a late-night dinner party, you might have absentmindedly left out your olives overnight. Are they still safe to eat? Or should you throw them away?
Unless you live in a hot and humid region, olives should be safe to consume after being left out overnight. We do not recommend leaving dry, fresh, and marinated olives at room temperature though. However, unless it is very hot, they will probably be okay to consume if it only happens once.
Remember to always inspect the olives carefully before consuming them. If the olives are in a state that causes you to doubt whether or not the olives are edible, I do not recommend eating them.
Is there a difference between black olives and green olives? What about olives cured in brine? We have all the answers to these questions and more, so read on!
What Happens If Olives Are Left Out Overnight?
What happens to olives when left out overnight varies somewhat on the variety of olives you purchased or made.
Most experts agree that olives soaking in oil, marinade, or simply purchased at the deli counter are not shelf stable after opening. However, olives made in the traditional Mediterranean method are stable at room temperatures.
There are several ways olives are preserved. The most common include:
- Soaked in oil
- Marinated
- Pickled
- Brine
Olives sold at your typical deli are usually soaked in oil or marinated in some fashion. They may be seasoned with garlic, onion, and other seasonings. However, these olives are not aged and do not have the preservation compounds as other preservation methods.
Leaving these olives at room temperature can make them become soft and unpleasant. After a few hours, the amount of bacteria grown in the marinade can cause sickness. The fermented taste will also be unpleasant, and the olives will taste moldy or musty.
The best way to preserve olives is in brine or to pickle them. The bringing method involves placing olives in a salty mixture and letting them age for several months. Olives are placed into large ceramic jars and coated in copious amounts of salt to create a brine solution.
These salted olives are placed in a dark corner and covered with a lid. As the olives age, they ferment into a pickled substance, allowing them to stay good at room temperature. You can purchase these olives at specialized traditional Italian markets and at some specialized supermarkets.
You can keep these olives at room temperature as long as it is below 65 degrees Fahrenheit (18.3 degrees Celsius). They should be out of the sun and stored for up to 6 months.
Is There a Difference Between Green and Black Olives?
Black and green olives are both the same fruit. The primary difference between the two olives is the level of ripeness. Green olives are unripe fruits of the olive tree, whereas black olives are the fully ripe fruit of the olive tree.
Flavor may be the main distinguishing factor between green and black olives. Black olives tend to be sweeter and are flavored with sweet wines and coupled with more decadent dishes. Green olives are more bitter and are used to create olive oil, and pair best with more savory dishes.
Both varieties of olives have a similar shelf life. They can both be cured in brine, or marinated in oil or water. Both have similar nutritional and fat content.
Can You Get Food Poisoning From Olives Left Out?
Any food which develops E.Coli, Chlodistrium, or other toxins can give you food poisoning. This is also true for olives, but they are not likely to go bad after being left out.
This varies depending upon how they were preserved and for how long they were left out. After 4 hours, you should check the quality of your olives before eating.
Olives do not spoil as quickly as other foods, especially when preserved in brine. Olives do not have high sugar levels, which prevents them from spoiling. But, they can spoil when the following conditions are met:
- The room temperature is above 75 degrees Fahrenheit (24 degrees Celsius)
- Olives soaked in water
- Olives soaking with other foods
- Dry olives
- Fresh olives
- Cross-contamination
- Uncovered jar or container
Bringing replaces the cell membrane of the food in a process known as “osmosis.” Osmosis pulls water and bacteria out of the food and seals the cell membrane in a salt solution. Salt, a common form of early bicarbonate toothpaste, is a natural antiseptic/antibacterial substance.
Thus, if your olives are properly prepared in a brine solution, they will not spoil at room temperature. You can leave these out without fear of food poisoning. However, dry olives or olives prepared with other foods can spoil at room temperature.
If your olives are stuffed with cheese, garlic, or cappers, you should not leave them out. These foods have a shorter shelf life and will probably develop bacteria if left out for 2 hours at room temperature.
Dry or fresh olives should only be left out for 4-6 hours before refrigerating. Dry olives may have oil or marinade, but they are not preserved and are considered dry. Since there is no preservative, such as salt brine, they can develop bacteria and cause food poisoning.
How Can You Tell If Olives Have Gone Bad?
The scent of olives is the best way to determine if they have spoiled. Spoiled olives will smell musty, moldy, or otherwise unpleasant. They may also appear mushy or soft or develop black or brown spots. Black olives will smell like vinegar and may get a syrup-like consistency.
Green and black olives have similar manifestations when they start to spoil. They usually start to break down due to age or contamination. This will usually cause their structural integrity to break down and become unpleasant.
If you notice your olives are no longer in their full form, this could mean they are spoiled. They may also break when you touch them with a utensil, signifying their structure is breaking down.
Just keep in mind they must appear mushy. Just because you can break an olive with a utensil does not mean they are spoiled.
If your green or black olives smell like mold, you should not consume them. This indicates that your olives are developing mold or fungal spores. Although some molds are harmless in small quantities, others can cause severe reactions.
Even harmless molds can be deadly when consumed in large quantities. All molds contain something known as mycotoxins. Mycotoxins harm the body and nervous system and can cause liver, kidney, and other organ failures.
To prevent mold and fungus from developing in your olives, keep them in a cool area. Olives stored in brine should be kept away from ovens and other heat sources. Refrigerate your olives if they are dry, fresh, or unpreserved.
Keep all olives covered, and avoid putting your hands in the container. Cross-contamination is the most common cause of food poisoning. Always use a properly cleaned utensil and cover olives after every use.
Should Olives Be Refrigerated After Opening?
Dry and marinated olives should be refrigerated after opening. However, when properly pickled or preserved in brine, olives can be kept at room temperature for up to 6 months. Proper storage of olives varies based upon preservation method and local environment.
If you purchase a jar of olives at the local grocery store, you should probably refrigerate them after opening. This is especially true for varieties where the manufacturer recommends you to refrigerate them.
Refrigeration will likely extend the shelf life of your olives. This is especially true for areas of the world where temperatures are regularly above 80 degrees Fahrenheit (27 degrees Celsius). If you have brine olives, make sure the space you store them is cool and dry.
The best place for brine olives is a basement or cold cellar. These spaces should be between 50-70 degrees at all times, and humidity should be limited (10-21 degrees Celsius). If your space is humid, try using dehumidifiers to keep the environment dry.
If you are worried your space is too warm or humid, keep your olives in the fridge. This will prevent them from spoiling and potentially growing harmful bacteria.
How Long Does an Open Jar of Olives Last?
Refrigerated olives can last up to 12-18 months when properly stored and treated. Properly cured and prepared olives can be kept in a cool, dry space for up to 2 years. Proper food handling and temperature control are olives’ most important storage factors.
If your jar of dry or marinaded olives is left out for prolonged periods, this will decrease its shelf life. It is important that you keep your olives in the proper environment to prevent mold and bacteria growth.
Follow the manufacturer’s recommendation if you are uncertain how to properly store your olives. However, if there are no specific directions on the container, follow these general guidelines:
| Type | Refrigerator | Shelf/room temperature |
| Dry or Fresh Olives | 12-18 months | 4-6 hours |
| Marinated w/ other ingredients | 6-12 months | 2-4 hours |
| Brine/pickled olives | 2 years | 2 years |
How Should Olives Be Stored?
Olives should be refrigerated when the directions specify you to do so. Olives stored on the shelf should be properly covered and away from heat and sunlight. Cool, dry environments are important for all types of olives, regardless of preparation.
Always keep your olives in a sealed jar or container with a proper lid. If you lose or break the original jar, replace it with a sealed plastic, glass, or ceramic container. Cover the container with plastic wrap or tin foil if you do not have a proper lid.
We recommend using a large ceramic container designed for this process if you make olives in brine at home. Do not use a metal container or plastic container for long-term storage. Plastic and metal containers might react with the acidic brine and contaminate the olives after a few months of storage.
Can You Store Olives in the Freezer?
You can keep olives in the freezer for up to 2-3 years in a properly sealed container or bag. However, we recommend using them within 6 months for optimal freshness and quality. Olives are sturdy fruits, but when frozen their structure becomes mushier and may deteriorate over time.
Freezer-safe, zipper-sealed bags are one of the best ways to store dry and fresh olives. Or, you can use a freezer-stable plastic or glass container.
Olives cured in brine store the best in the freezer. These can be stored in a glass container along with the brine solution. This liquid help preserve the olives’ structural integrity and flavors.