Does Mustard Go Bad?

In this brief guide, we will answer the question, “does mustard go bad?” as well as other questions,like how long does mustard take before going bad and how to store mustard to ensure optimum shelf life.

Does mustard go bad?

Yes, mustard can go bad, especially when not correctly stored or when it has been contaminated. 

What is the shelf life of mustard? 

The shelf life of mustard is 2 years if stored unopened. On the other hand, an opened package/jar of mustard will only last for about 1 year in the refrigerator. In addition, shelf-stable commercial mustard is safe even when stored at room temperature after opening (2).

However, if you store unopened mustard in the refrigerator, it can last longer. Refrigeration ensures that commercial sauces and condiments stay fresh for a longer period of time. 

How To Store Mustard?

Mustard should be stored in a cool and dark place, away from sources of heat and sunlight. You can store an unopened jar or bottle at room temperature, which means a pantry or a kitchen cabinet are the most indicated options.

Once you open the mustard, it is susceptible to the actions of the environment, the presence of oxygen and possible microbial contaminations. Therefore, it is necessary to maintain the bottle tightly closed when not in use. 

If the jar isn’t sealed well, the mustard may lose moisture. In addition, the presence of oxygen leads to oxidation. It is well accepted that higher temperatures increase lipid oxidation (4).

Always use clean utensils when scooping the mustard. Scooping the condiment with utensils already used for other purposes will likely transfer bacteria and contaminants to the mustard. Use plastic utensils. The contact with metal and possible release of metal ions lead to oxidation (4).

Light promotes the oxidation of unsaturated fats due to photo-synthesized oxidation (4). It is necessary to prevent mustard from the exposure of light. 

Mustard, if stored for a long time, tends to separate and this is quite normal. Emulsions are thermodynamically unstable systems, due basically to a high interface area, which leads to a spontaneous phenomenon of aggregation of drops. 

This phenomenon is accelerated at higher temperatures (3). Therefore, the quality of mustard will be longer preserved, when the product is stored in low temperatures.

What affects the shelf life of Mustard?

The main factors that affect the shelf life of mustard are the storage conditions, the composition of the product and its packaging material.

Mustard is an emulsion and the stability of emulsions are determined by their composition, as they will affect their physicochemical properties. Mustard is considered an acidic product, with a pH of around 4. Higher concentrations of acetic acid (as a form of vinegar) in the mustard formulation prevent the growth of most bacteria and all bacterial pathogens (5).

The antioxidant property of the mustard seed, which is due to the presence of isothiocyanates and other volatile sulfur compounds, may reduce the rate of lipid oxidation. Higher concentrations of mustard paste in the dressings are related to a lower rancidity during storage (4). 

Finally, the packaging material affects the shelf life of mustard. Mustard cannot be exposed to moisture, oxygen and light and therefore needs packaging with effective barriers to these environmental factors. 

In a study comparing different packaging materials used for salad dressings (PVC, PE/PA, and PS), PVC was shown to be able to achieve greater conservation of the sensory attributes of the sauces (6).  

Can you consume Mustard after the expiration date?

Yes, you consume mustard after the expiration date, unless you identify signs of deterioration of the product.

All mustards come with a “best-by” date which informs you of how long the mustard should retain freshness. The “best-by” date is an indication of quality rather than of safety and due to its high acidity, mustard may be safe to use after the expiration date. 

With an exception of infant formula, if the date passes during home storage, a product should still be safe and wholesome if handled properly until the time spoilage is evident. Spoiled foods will develop an off odor, flavor or texture due to naturally occurring spoilage bacteria. If a food has developed such spoilage characteristics, it should not be eaten (6).

Deteriorated mustard can be identified through off-odors and off-flavors, bloating of the packaging, formation of visible mold and formation of slime on the surface of the product (5).

Other FAQs about Mustard which you may be interested in.

What happens If you eat expired mustard?

Can you get sick from eating expired mustard?

How To Tell If Mustard Is Bad?

Like many other condiments, mustard can go bad, but that’s a quite rare occurrence. Check for the following signs that indicate unusable mustard:

Texture: One of the signs that indicate unusable mustard is the texture as it loses its texture over time. If there are any noticeable lumps below the container, then it is a sign that your mustard has gone bad (3).

Mold: Growing of mold inside the container is another sign that indicates unusable mustard. Common spoilage microorganisms in mustard are L. plantarum and Z. bailii. Some signs of microbial contaminations are slime formation, off-flavors, and off-odors. Mold growth is obvious with visible mycelia on the surface of the product or liquefaction of the product (5).

Taste: Taste is another sign that can indicate unusable mustard. When stored for a very long time, mustard usually loses its original flavors. If you notice any changes with its taste, then it is time to discard it. Lipid oxidation in dressings containing lipids leads to the development of potentially toxic reaction products, undesirable off-flavors and consequently decreases the shelf life of the products (4).

Smell: The most common way to tell if mustard has gone bad is its smell. Any unpleasant or sour smell indicates that the mustard has one bad smell. Lipids decompose to aldehydes, ketones, alcohols, hydrocarbons, volatile organic acids and epoxy compounds known as secondary oxidation products, which are responsible for the off-flavor and off-odor of the oil (4).

Other FAQs about Mustard that you may be interested in.

Does Mustard Get Rid Of Heartburn

How to counteract too much mustard in a dish?

Can dogs eat mustard?


In nutshell, mustard usually tends to stay fresh longer. However, the quality of your mustard cannot sustain forever. As mustard degrades in quality over time, it is quite possible that you will discard the condiment for quality purposes, not because it has spoiled. If there aren’t any signs of it going bad, give it a taste. If the flavor is good enough to use, feel free to continue using it. Otherwise, throw it out.


  1. Lietzow, Julika. Biologically Active Compounds in Mustard Seeds: A Toxicological Perspective. Foods, 2021, 10, 9. 
  2. FSIS’ FoodKeeper. US Department of Agriculture
  3. Lozano-Gendreau, M., and J. F. Vélez-Ruiz. Physicochemical and flow characterization of a mustard-vinaigrette salad dressing. J Food Sci Nutr Res, 2019, 2, 253-269.
  4. Gorji, Sara Ghorbani, et al. Lipid oxidation in mayonnaise and the role of natural antioxidants: A review. Trend Food Sci Technol, 2016, 56, 88-102.
  5. Sperber, William H. Microbiological spoilage of acidified specialty products. Compendium of the microbiological spoilage of foods and beverages. 2009.
  6. Giménez, Cecilia G., et al. Development of a bioactive sauce: Effect of the packaging and storage conditions. ChemEngineering, 2022, 6, 34.