Can Green Olives Go Bad?

In this short article, we are going to provide an answer to the question, “Can green olives go bad?”, with an in-depth analysis on how to tell if they have gone bad, how to store a green olive and what happens if you consume spoiled green olives..

Can green olives go bad?

Yes, green olives can go bad after its expiration date and if it is improperly stored. It is also possible that green olives have been contaminated and expired before their expiration date.

Signs that green olives have gone bad include a foul odor, mold growth, slimy texture, or a significant change in taste. If you notice any of these signs, it’s best to discard the olives to avoid any potential health risks (1,2).

The standard of brining, fermentation techniques are also an indication of the life span of green olives. Canned and jarred olives have a different expiry duration than the freshly obtained ones (3).

How to tell if green olive has gone bad??

The best way to identify if green olives have gone bad is by assessing the smell. If it has a remotely different smell or a strange odor, it should be discarded immediately. The table olive industry occasionally reports spoilage of fermented green olives associated with increases in brine pH and unpleasant odors (1).

You can check through the odor, in which three different types of malodorous deterioration have already been recognized in this product: zapatera, butyric and putrid. Although some odors are difficult to describe (zapatera), they are clearly abnormal and very distinct. The butterfly spoilage resembles the smell of rancid butter, while the putrid type resembles the smell of decaying organic matter (1).

The volatile metabolites produced by the microorganisms of the genus Clostridium are also involved in the deterioration of the olive and are responsible for the bad smell (1). The development of fungi during the fermentation of olives leads to softening of the fruits and sensory defects such as odors and moldy flavor (3).

Some varieties will also show signs of rot or mold, mainly due to moisture in the storage space or unhygienic handling of food. Mold can be white and thin and is easy to observe, if it is seen on a single olive, it is better to discard the entire jar or can. If rot is observed in fresh green olives, get rid of the whole batch, as it contains mostly infected bacteria (2).

The main microbial genus isolated in olives is Lactobacillus (4). Enterococcus, Pediococcus, Leuconostoc and Lactococcus have also been isolated, but to a lesser extent (5). In spoiled olives other bacteria were also found, including species of Suttonella and numerous unclassified Lactobacillaceae (6).

While bacteria Propionibacterium acidipropionici and Propionibacterium microaerophilum were isolated from anomalous fractions occurring in the post-packaging of hermetic plastic bags of green olives of Spanish style (5).

The presence of brine is also an indicator of the quality of the olives. If the brine dries, it is better to check other factors to see if the olives maintain the proper pattern for consumption: firmness, good coloration and absence of odors (14).

What is the shelf life of green olive?

The shelf life of green olives can vary depending on various factors, such as their packaging, storage conditions, and whether they are opened or unopened. Here we separate some general guidelines for you:

Unopened commercially packaged green olives

Unopened jars or cans of commercially packaged green olives typically have a long shelf life. They are often labeled with an expiration date, which indicates the estimated time frame for the olives to retain their best quality. These olives can often last for one to two years past the expiration date if stored properly (7).

Opened green olives (in brine)

When stored in the refrigerator, opened green olives can generally last for several weeks to a few months, depending on their condition at the time of opening. The brine or liquid in which the olives are packed helps preserve their freshness. However, it’s always advisable to check for signs of spoilage, such as a foul odor, slimy texture, mold growth, or off taste, before consuming them (8).

If you have purchased fresh green olives from a deli or farmer’s market, they are typically less processed and have a shorter shelf life. Fresh green olives should be stored in the refrigerator and consumed within a week or two for optimal quality (8,10).

What affects the shelf life of green olives?

Green Olive Packaging 

The type of packaging can significantly impact the shelf life of green olives. Commercially packaged green olives in jars or cans are usually sealed and designed to preserve the olives’ freshness and quality for an extended period. These containers help protect the olives from exposure to air, moisture, and contaminants. Properly sealed packaging helps to prevent spoilage and maintain the olives’ shelf life (7).

Green Olive Processing and Preservatives

Green olive shelf life can be affected by processing methods and the use of additives. Olives that have been thoroughly processed, such as curing or brining, and that have been treated with preservatives such as citric acid or vinegar have a longer shelf life. These procedures aid in the prevention of the growth of bacteria, yeast, and mold, which can lead to spoiling (9).

Storage Conditions of Green Olive

Proper storage conditions are critical in extending the shelf life of green olives. Temperature, light, and air exposure can all have an impact on the quality and durability of olives. Green olives should be stored in a cool, dry place away from direct sunlight. Once opened, it is best to keep them in the refrigerator to inhibit bacterial growth and keep them fresh (10).

Contamination

The presence of pollutants might hasten the deterioration of green olives. When serving or scooping olives from the jar, it is critical to use clean hands and utensils. Contaminants, such as filthy tools or double-dipping, might introduce bacteria or other germs into the olives, potentially shortening their shelf life (2,3).

How to properly store green olive?

Store olives at 41° to 50 °F, especially in shallow, ventilated crates, for the greatest quality. Fresh olives stored at cooler temperatures (32° to 36 °F) for 2 weeks or more might suffer from chill injury, resulting in internal browning and skin browning (10).

Chill injury should not be an issue if the olives are only exposed to cooler temperatures over brief periods of time. Sevillano olives are the most vulnerable to chill injury, followed by Ascolano, Manzanillo, and Mission (the least). Surface pitting can occur when fresh olives are stored at 50 °F for an extended period of time (6 weeks or more) (10).

In general, the way you store them indicates the longevity of the olives (1,10,11).

• Storing olives in brine is the most effective way, as they can be preserved for a long period of time, even years, if they remain closed. However, open jars even in brine last much less time than that.
• Canning is a common olive preservation process in the food industry. During canning, food is sealed in airtight containers and pasteurized by heat.
• The low concentration of salt is the main factor for deterioration. The different levels of alkalinization and washing were not significant to prevent or favor the deterioration of green olives.
• Oilseed green olives should be consumed within 2 weeks. Otherwise, they may spoil or exude an unpleasant odor.
• Maintaining a good standard of hygiene after opening the package is also a way to keep the olive within the standard.
• Make sure that the olives are completely submerged in the brine, as the dried olives become brittle and prone to rotting.
• It is advisable to store the olives in brine or oil stored in the refrigerator, as this prolongs the shelf life of the olives and prevents them from developing mold.
• Proper salting techniques and maintaining a stable salty environment keep the olives fresh for a long time.

·        

What happens if you consume spoiled green olives? 

Spoiled green olives can present molds in the brines such as Penicillium, Aspergillus and Fusarium, and can compromise the safety of the product, especially in the case of mycotoxin-producing fungi  (12).  In addition to altering the taste, odor, color and texture of food, rep mycotoxins pose a risk to human health (13).

Knowing that consuming expired green olive has many negative impacts on the general health of an individual; that is why it is advisable to thoroughly check the quality of one before consuming it. But if due to some reason you have accidentally consumed one, here are some effects it might have on you.

• Stomachache is the first and most common symptom.
•  Eating a moldy or rotten olive can lead to nausea and dizziness.

•  In some cases, a bad olive can result in a severe case of dehydration.
• Some people have also experienced vomiting and diarrhea because of a faulty olive.

Conclusion:

In this short article, we have answered the question, “Can green olives go bad?”, with an in-depth analysis on how to tell if they have gone bad, how to store a green olive and what happens if you consume spoiled green olives. 

References:

1. De Castro, A., et al. “A Microbiota and metabolite profiling of spoiled Spanish-style green table olives”. Metabolites. 2018; 8(4): 73. 

2. F. Pérez-Nevado, P.P., et al. “Identification of molds associated with green table olives”. Microorganisms in Industry and Environment, 2010, 398-402. 

3. Cocolin, L.,et al. “NaOH-debittering induces changes in bacterial ecology during table olives fermentation”. PLoS One. 2013; 8 (7), e69074. 

4. Hurtado, A., Reguant, C., Bordons, A., & Rozès, N. “Lactic acid bacteria from fermented table olives”. Food microbiology. 2012; 31 (1), 1-8.

5. Lucena-Padros, H., et al. “Propionibacterium olivae sp. nov. and Propionibacterium damnosum sp. nov., isolated from spoiled packaged Spanish-style green olives”. International journal of systematic and evolutionary microbiology. 2014; 64 (9): 2980-2985. 

6. Golomb, B. L., et al. “Effects of pectinolytic yeast on the microbial composition and spoilage of olive fermentations”. Food microbiology, 2013, 33(1), 97-106.

7. Aikaterini Tzamourani . “Effect of Packaging on Microbial Survival and Physicochemical Characteristics of Non-Thermally Preserved Green Spanish-Style Olives”. Proceedings, 2021, 70, 61

8. Lombardi, S. J. et al. “Effect of different storage conditions on the shelf life of natural green table olives”. Italian Journal of Food Science, 2018, 30(2).

9. Alves, M. “Effect of preservatives and acidifying agents on the shelf life of packed cracked green table olives from Maçanilha cultivar”. Food Packaging and Shelf Life, 2015, 5, 32-40

10. Yada, S. et al. “Olives: Safe Methods for Home Pickling”. Home Food Preservation and Food Safety, 2007 

11. 9. Jafarpour, D. The effect of heat treatment and thermosonication on the microbial and quality properties of green olive. Journal of Food Measurement and Characterization, 2022, 16(3), 2172-2180. 

12. Zinedine, A., & Mañes, J. Occurrence and legislation of mycotoxins in food and feed from Morocco. Food Control. 2009, 20, 334-344.

13.  Moretti, A.; Logrieco, AF; Susca, A. “micotoxinas: um problema alimentar dissimulado”. Mycotoxigenic Fungi,  2017, 1541 , 3–12. 

14. Lanza, B. Nutritional and Sensory Quality of Table Olives. InTech. 2012