Yes, nutritional yeast does go bad. However, nutritional yeast is very resistant to expiring if stored correctly since it is a dried product.
One published review of nutritional yeast found that nutritional yeast powder has an average shelf life of 12-24 months.
If nutritional yeast is stored in an air-tight container in a cool and dark area, it often lasts a few months past the expiration date without any significant signs of degradation.
Let’s look at how to tell if nutritional yeast is expired, and ways to extend its shelf life.
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Food Spoilage 101: How Does Food Go Bad?
Food can go bad in many ways, but ultimately it’s usually degradation caused by one of the following:
- Enzyme activity
The good news is that:
- Nutritional yeast is already heated (i.e. cooked), so it has very little enzyme activity
- As a dried food, there shouldn’t be enough moisture for significant microorganism growth
- If sealed in an air-tight container, oxidation will be very slow
Putting all this together is why you’ll see an expiry date of 12-24 months on packages of nutritional yeast.
This may vary based on manufacturer, who may have different manufacturing processes, risk tolerances, or levels of sterilization.
How to Tell If Nutritional Yeast Has Gone Bad
Compared to other foods, it’s tougher to tell if nutritional yeast has gone bad because it naturally has a bit of a weird smell.
Still, there are various hints that nutritional yeast has gone bad:
- Color – Nutritional yeast tends to turn a darker, brownish color as it goes bad, compared to the bright yellow of fresh nutritional yeast. If mold exists, there will be obvious green spots (in which case, toss it).
- Clumping – Spoiled nutritional yeast has a tendency to stick together. This may be as a result of moisture entering the food, or just degradation of the yeast.
- Smell – While nutritional yeast smells a bit weird even when fresh, expired nutritional yeast smells different. If possible, compare your nutritional yeast to a new package and see if the old yeast smells off.
- Taste – Taste testing a food that might be bad is the last resort. Eat a small amount and if it lacks flavor or tastes weirdly bitter, it’s likely bad.
Can Expired Nutritional Yeast Make You Sick?
If nutritional yeast is only a bit expired, it’s unlikely to make you very sick. The most likely symptoms are some gas and an upset stomach.
If you notice these symptoms after eating food with nutritional yeast in it, toss the package. Even just a tablespoon or two can cause these symptoms.
In the case that the nutritional yeast is very expired, and there’s obvious mold growth, then yes, it could make you quite sick. But it should be obviously bad in that case.
Why Does Nutritional Yeast Go Bad?
Even though nutritional yeast is a dried food that’s already been heated, it can still go bad.
Unless the manufacturing environment is perfectly sterile, there’s always going to be some microorganisms in a package of nutritional yeast. Over time, those will replicate and grow, which degrades the food.
In addition, since packages aren’t vacuum sealed, there’s obviously exposure to air, which leads to some level of oxidation (although it’s relatively low in air-tight containers).
Does Nutritional Yeast Go Bad in the Fridge?
Cold temperatures slow the growth of all microorganisms (some more than others, like yeasts).
So if you store nutritional yeast in the fridge, it will last longer. However, it will still eventually go bad (i.e. there’s still oxidation and some level of microorganism growth).
While it depends on the temperature, storing nutritional yeast in the fridge will help extend the shelf-life by at least a few months in most cases.
Can Unopened Nutritional Yeast Go Bad?
Unopened nutritional yeast is less likely to go bad early than an opened package, but if you leave a bag of nutritional yeast on the shelf for years, it can still go bad.
While it wouldn’t have been exposed to additional moisture or fresh air, there’s still a slow level of degradation occurring due to the reasons we looked at above.
How Long Is Nutritional Yeast Good After the Expiration Date?
I’ve had nutritional yeast that was still perfectly fine a year past the expiration date. But I’ve also had nutritional yeast go bad before the expiration date.
If you’ve stored it in an air-tight container in a cool and dry environment, nutritional yeast is more likely to last months after the expiration date.
On the other hand, if it’s been exposed to air and moisture, it likely will go bad by the expiration date.
In either case, look for the signs of spoilage that we went over before, it’s the only way to know if it’s gone bad. If you want to be on the safe side, buy small packages of nutritional yeast and throw them out if you have any left by the expiration date.