Does oyster sauce go bad?

In this brief guide, we are going to answer the question “Does oyster sauce go bad” with an in-depth analysis of whether or not oyster sauce can go bad. Moreover, we are going to discuss the shelf life of oyster sauce, ways to spot bad oyster sauce, and the proper way to store it.

So without much ado, let’s dive in and figure out more about it.

Does oyster sauce go bad?

So like all other food items oyster sauce also goes bad after a certain time. Once the oyster sauce goes bad, you will feel a difference in its smell, taste as well as appearance.

The oyster market accounts for more than 12% of EU aquaculture in terms of production value and it is therefore relevant for the whole seafood sector (1).

How long does oyster sauce last?

Commercially bottled, store-bought oyster sauce, lasts for about 18 months to 2 years in the fridge at or below 40 degrees Fahrenheit, once it gets opened and that’s quite a long shelf life. Refrigeration ensures that commercial sauces and condiments stay fresh for a longer period of time. Shelf-stable commercial sauces are safe when stored at room temperature after opening. Quality, not safety, is the reason the labels on these products suggest that they be refrigerated after opening. But according to the FoodKeeper app, you should consume your oyster sauce within 3-6 months, once it gets opened (2).

On the other hand, an unopened bottle of oyster sauce stored in a cool, dry, and dark corner of your pantry away from direct sunlight and heat lasts for about 18-24 months easily (2).

It is worth mentioning that these figures are just the estimated shelf life of oyster sauce and oyster sauce can even last for more than this, provided that it was stored properly. 

You can read about how to use oyster sauce here.

Is oyster sauce safe to use after the best-before date?

The “best by” or “best before” date that is written on the bottle of oyster sauce refers to the quality rather than safety so the oyster sauce doesn’t necessarily go bad immediately after the best before date (7). It is the time during which you can enjoy the peak quality and flavor of oyster but you can still use oyster that is past this date as long as it was stored properly and there is no leakage or mold in the bottle of oyster sauce.

How to tell if the oyster sauce has gone bad?

You should consider the appearance, smell, texture, and taste of oyster sauce to give a final verdict of whether or not oyster sauce has gone bad.

Oyster sauce, similarly to fish sauce, contains high amounts of salt, which acts as a food preservative, preventing microbial growth. However, some bacteria, called osmophilic and halophilic microorganisms (yeasts and bacteria) can grow in food with a high amount of salt. In the case of oyster sauce, which contains up to 20% by weight of salt, some moderately halophilic bacteria are involved in the spoilage. In general, the spoilage can be detected by using organoleptic tests (odor and visual evidence of spoilage such as slime or gas formation) (3).

Appearance

If you spot a microbial biofilm, slime or organic growth on your oyster sauce, then the best thing you can do is to get rid of the sauce as it is an indication of bad oyster sauce but it is a really rare phenomenon (8). If you consume such oyster sauce, it can cause many foodborne illnesses including food poisoning that is characterized by nausea, vomiting, diarrhea, abdominal cramps, and sometimes even fever. 

Moreover, if you see a green or white fuzz in the bottle of your oyster sauce then it is better to get rid of it.

Smell

If you smell something unpleasant or something that quite does not feel like the oyster sauce itself while taking a sniff test of oyster sauce then it most probably means that your sauce has gone bad and you should get rid of it.

During long storage, oyster sauce, which contains fatty acids, may oxidize and produce off-odors. Oxidative rancidity generally occurs in fatty fish. Primary and secondary lipid oxidation products are the biological amino compounds, proteins, peptides, free amino acids and phospholipids; these react to produce interaction compounds and this makes the color of the product brown, causes a change in flavor and loss in aromatic nutrient elements (4).

Texture

Cornstarch is added to the oyster sauce during its processing to thicken it, so if you notice that water has started to get separated from the rest of the sauce and there can be seen separated layers based on the difference in densities that don’t make one homogenous layer again even after shaking or swirling the bottle, then it is better to discard such oyster sauce. Microbial contamination may cause changes in the texture. In addition, degradation of proteins can cause gelation and aggregation of protein molecules, followed by the formation of an irreversible three-dimensional network, resulting in precipitation (5).

Taste

With time, the flavor of oyster sauce begins to get stronger, so if it gets too strong that it begins to mess up the taste of the dish in which you are using it, then it is recommended to get rid of such oyster sauce.

How to properly store oyster sauce?

  1. Oyster sauce darkens in color and becomes stronger in flavor quickly when it comes in contact with oxygen or sunlight owing to the oxidation reaction. Therefore to seal the freshness of oyster sauce for quite a long time, you should close the lid of oyster sauce as soon as you are done with pouring out the quantity that you need and you should always store it away from direct sunlight.
  2. You can store the unopened oyster sauce easily in a cool, dry, and dark corner of the pantry or kitchen cabinet away from direct sunlight and heat (6).
  3. When you have opened the oyster sauce it is better to store it in the refrigerator at or below 40 degrees Fahrenheit (2).

Conclusion

In this brief guide, we answered the question “Does oyster sauce go bad” with an in-depth analysis of whether or not oyster sauce can go bad. Moreover, we discussed the shelf life of oyster sauce, ways to spot bad oyster sauce, and the proper way to store it.

Citations

  1. Santeramo, Fabio Gaetano, et al. On consumption patterns in oyster markets: the role of attitudes. Marine Policy, 2017, 79, 54-61.
  2. FoodKeeper. United States Department of Agriculture. 
  3. Kim, J., Elena Enache, and Melinda Hayman. Halophilic and osmophilic microorganisms. Compendium of Methods for the Microbiological Examination of Food. 2014.
  4. Kilinc, Berna, et al. Chemical, microbiological and sensory changes associated with fish sauce processing. Euro Food Res Technol, 2006, 222, 604-613.
  5. Moon, Kyung-Whan, et al. Prevention of precipitation in sand lance fish sauce by chelating agents. Food Sci Biotechnol, 2008, 17, 114-117.
  6. Food Storage in Home. Utah State University.
  7. Gravely, M. Before you toss food, wait. Check it out!. United States Department of Agriculture. 2022. 
  8. Rawat, Seema. Food Spoilage: Microorganisms and their prevention. Asian j plant sci Res, 2015, 5, 47-56.   

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