How To Tell If Mustard Has Gone Bad

If you have a set of sauces in your fridge, you may find that some are not as fresh as some of the more processed sauces. Mustard is one of the sauces that last for years when in the fridge, but years can’t be forever so… how do you know when the mustard has gone bad?

When the mustard has a strong sour or rotten smell, the flavor is wrong, the overall look has changed, or mold has started to grow, it is bad. Some can last for over a year, while store-bought have printed labels that give you the exact date. 

Homemade mustard

The world of mustard has seen more recipes and adjusted expiration dates than almost any other sauce on earth. This condiment generally consists of mustard seeds, vinegar, water, and spices. We have looked at the most common recipes from around the world and determined how each one expires in hopes of helping you know when it is safe to eat. 

Homemade Vs Store-bought

It is very important to make this distinction first. Here’s a table for easy comparison between homemade and store-bought mustard:

AspectHomemade MustardStore-Bought Mustard
IngredientsCustomizable, often simple and natural ingredients (e.g., mustard seeds, vinegar, water, salt, spices)May contain a wider range of ingredients, including additives, preservatives, and artificial flavors
FlavorCustomizable and can have a complex, personalized flavor profileStandardized flavors with consistent taste
TextureVariable; can be smooth, coarse, or whole-grain, depending on preparationTypically has a uniform and smoother texture
CustomizationHighly customizable; can create unique varietiesLimited customization; choose from available options
FreshnessTypically fresher due to control over when it’s madeMay sit on store shelves for an extended period
PreservativesOptional; can be made preservative-free or use natural preservative.Usually contains preservatives and additives

This table summarizes the key differences between homemade and store-bought mustard across various aspects. 

However when it coes to determine if it has gone bad, there is not much difference at all.

There are generally no significant differences in the signs of spoilage between homemade and store-bought. The key indicators of spoilage, such as mold growth, off odors, changes in texture, color, or taste, are similar for both types of mustard. Whether it’s homemade or store-bought.

The main distinctions between the two types lie in their ingredients, flavor, and texture, as explained. 

When it comes to food safety and recognizing spoilage, the principles are largely the same, and it’s essential to rely on your senses and common sense to determine whether mustard is safe to consume or you should discard it to avoid any food poisoning.

What Are The Four Signs Mustard Has Gone Bad?

When it comes to knowing when this popular condiment has gone off or has turned fully into the home of a multitude of species, you need to remember four things. Each of these will tell you when something has gone wrong; however, observe the signs to know the severity of the expiration. 

You can often know that the condiment is going bad just by a few simple signs that you can see through the side of the can. We always recommend that you try to get rid of the mustard when it starts going bad, as the smell of bad mustard can linger in your fridge into your next one. 

The Look

When it starts going bad, it starts developing clumps with clear liquid instead of being uniformly yellow. If you see this through the side of the jar, it is time to replace it with store mustard, only showing this once you squirt some out. 

Note that you should shake mustard before using it each time to ensure everything mixes properly. This is often why the early signs of going bad are not noticed, as the shaking of the bottle allows the clumps to become mixed in. 

Fluid Levels

The second sign that mustard is bad is when the water content has started dropping, usually becoming harder and harder to use. Many homemade ones have a layer of water on top, with many mistakenly thinking it should just be mixed back in. 

We always recommend that you take a moment to check when the it was made; as the water separates from the mustard, it is a sign that things have gone bad. You can often discard it when it becomes so viscous that it no longer mixes or pours easily. 

The Smell

Different types have different kinds of smell, but all of them have the same great aroma of mustard when they are fresh. And that bad smell once it has gone bad. It is best described as a sour smell mixed in with something slowly rotting; once this smell starts to develop, it should be thrown away. 

If your mustard has started to smell bad, you cannot safely eat it anymore as it is a clear sign that bacteria dangerous to the human gut is growing. When this bacterium grows and you ingest it, it can cause deadly health risks that can cause weeks of problems that can land you in the hospital. 

Mold On The Mustard

The sign that you should seal the mustard bowl or bottle and throw it all away is when there is mold growing. The mold can be greyish, green, or black; smelling it can cause mold spores to enter your lungs and cause permanent health problems. 

We can never stress enough that mold growing on anything is never safe to ingest or even smell as it can be deadly. Skipping one or two meals is always better than trying to risk your life just because you are assuming that the mustard made three years ago is safe to eat. 

Store-bought mustard

Is It Ok To Eat Expired Mustard?

Store-bought one has a specific day on which it expires, after which it will rapidly degrade in quality, taste, and smell. Note that this expiration date is common in store-bought products as they have several chemicals that expire after several weeks. 

When making it homemade, you will usually use much fewer additives, which means the mustard can last much longer. Pure mustard does not expire easily, with most sauces that use mustard having the other ingredients expire before the mustard itself goes bad. 

We recommend you write the date on the tin or jar in which you are storing it. Only using it for the maximum time of one year after this date, allowing you always to be safe and to make a fresh batch of mustard at the same time each year. 

Do you Have to Keep Mustard in the Fridge?

Whether you need to keep it in the fridge depends on the type:

  1. Store-Bought : Most commercially produced mustard, such as yellow mustard, Dijon mustard, or spicy brown mustard, usually contains preservatives and vinegar, which help prolong its shelf life. These store-bought ones are typically safe to store in a cool, dry pantry or cupboard. However, refrigeration can extend their shelf life and help maintain flavor and quality, especially after opening. If you use store-bought mustard infrequently or want to maximize its freshness, the right spot to store it is in the refrigerator after opening.
  2. Homemade: Homemade mustard, which may lack commercial preservatives, vinegar, or other stabilizers, benefits from refrigeration, particularly after opening. Storing it in the fridge can help prevent spoilage and maintain its quality for a more extended period.

In summary, while it’s not always necessary to keep store-bought one in the fridge, refrigeration can help preserve its freshness and extend its shelf life. For homemade mustard, it’s generally a good practice to refrigerate it, especially if it lacks commercial preservatives. Always check the label for any specific storage recommendations provided by the manufacturer, and use your judgment based on the mustard’s ingredients and your usage patterns.

Shelf life of mustard past their best-by dates:

Mustard TypeUnopened Shelf LifeOpened (Refrigerated) Shelf Life
Yellow Mustard1-2 years1 year
Dijon and Brown Mustard2-3 years1 year
Honey Mustard2-3 years1-2 years
Dry Mustard1-2 yearsN/A (store in the pantry)

*Please note that these are approximate timeframes and can vary depending on storage conditions. 

How Long Does Mustard Last Once Opened?

How long mustard will last once you have opened it is around two to three months before it expires and becomes inedible. We recommend that you use it as fast as possible to ensure that the taste is always as good as possible, avoiding disappointment in the future. 

The mustard you bought is filled with nitrogen gas to ensure no bacteria or contaminants can grow. Once you open it, oxygen enters the bottle, and things can start going bad, causing your mustard to be full but still be inedible if you have only used it once or twice. 

We recommend that you only open it when you know it will be completely used up within a few weeks from opening it. 

Your homemade one though won’t spoil that quick. If it has been freshly packed will usually last significantly longer than this once opened because of the process and the higher concentration of a mustard powder. 


You will know that your mustard has gone bad when the parts have started to separate, and the smell of the mustard has turned bad. Once mold has started growing on the mustard, the only safe thing you can do is to throw everything away, making sure not to open it. 

Although there are different types of mustard, there is not much difference when it comes to going bad.

So consider these essential tips. Store it at room temperature in a cool, dry place, away from direct sunlight. Opt for a glass jar instead of plastic squeeze bottles, as they are less likely to absorb odors and flavors and can maintain the mustard’s quality. Always use clean utensils.

These measures help preserve mustard’s freshness and flavor, ensuring it remains safe and enjoyable for longer periods. Remember though, that fresh mustard always tastes much better than almost any other mustard you can buy.

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