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Can Whey Protein Go Bad?

If you always buy whey protein in bulk, sooner or later one of the containers or pouches will hit its best-by date. When that happens, should you toss out the rest, or continue using it?

You already know that powdered products don’t spoil the same way meat or dairy does. And if whey powder is only a week or two past that date, it looks pretty much like it always does. There are no visible changes, the smell stays the same, and so does the taste.

But as an athlete, you’re also concerned with the nutritional side of things. So you’re wondering if the expired protein powder is as effective as one that’s still in date.

In this article, we will go through the most common questions related to long term storage of whey protein. We will talk specifically about when and if you should discard the expired powder, and how to store it, so it lasts as long as possible.

Scoop of cocoa whey powder
Scoop of cocoa whey powder

Can Whey Protein Go Bad and How To Tell If It Is Bad?

I think we can agree that it’s common knowledge that powdered food products such as whey protein (or protein powder in general) don’t go off or moldy. Not on their own, at least.

Even if some microbes got into the container during the packaging process, there’s very little water in there. There’s nothing for them to feed on and grow.

So, does that mean whey protein can’t go off? Of course not.

If water gets inside the container or pouch, it will form lumps and likely grow mold within a few days. So when you notice that your protein supplement is wet, starts to resemble wet sand, or has some big wet lumps in it, discard it. Same thing if you notice any signs of mold in the package, obviously.

Post Workout Nutrition
Image used under Creative Commons from Tomos

One thing to note here is that some whey protein supplements are most dust-like than others. Thus you shouldn’t compare the consistencies of different products, because they can be slightly different. Always check the current “wetness” of the product against how “wet” it was when you first opened the package.

One more thing we need to talk about here is quality. At a certain point, the whey protein might stop tasting as good as it used to. The flavor of the powder tends to degrade over time, and when it reaches a point that you’re no longer happy with it, toss it out.

Okay, now you know how to tell if whey protein is bad. And you see that yours is fine, but it’s after the date on the label. What should you do?

Whey Protein
Image used under Creative Commons from David van der Mark

Does Whey Protein Expire or Lose Effectiveness?

The date on the label of whey protein is there for at least two reasons. One of them is quality. Even though the product is in powdered form, it gradually degrades in quality. It’s like with spices, such as cinnamon, that over time lose some of their tastes.

The same is with protein powders, especially those with very distinct flavors. That flavor gradually fades, and at a certain point, it won’t be good enough anymore. Usually, the shelf life of whey protein is between a year and two years ([PN]). It all depends on the kind and amount of preservatives and flavorings used in making the supplement.

Male body from protein powder
Male body from protein powder

The second reason is that at a certain point the whey protein starts to slowly digest itself, so to speak. The process is called the Maillard reaction ([WIKI]) and it occurs in old whey powder ([NCBI]).

It sounds much worse than it really is. Basically, the sugar in the powder starts to break down the amino acid called lysine, which makes the protein “less complete.” In layman’s terms, you lose some of the nutritional value of the supplement.

If you can live with that, it’s still okay to eat whey powder that’s technically “expired.” So whey protein might lose a bit of its “potency” over time, but it’s definitely not like baking powder that after a certain period it’s virtually useless.

When it comes to the shelf life of whey protein, opening the pouch or container doesn’t really change much. In many places, you can read that you should finish the opened container of the supplement within six months or a year. But that has more to do with the storage and handling of the product, than with the product itself.

I guess it’s time to talk about how to store it, so it lasts as long as possible.

Three measuring metal scoops of whey protein powder
Three measuring metal scoops of whey protein powder

How To Store Whey Protein?

Like all powdered products, you should keep whey protein in a dry spot away from sources of heat. A dark cupboard in the kitchen or pantry is just fine. Keeping the moisture at bay is the most important thing to take care of.

Once you open the package, make sure it’s always sealed tight. If it’s a resealable pouch or container, the producer took care of that for you. If not, use an airtight container. Or if you have one of those cereal dispensers gathering dust in the closet, you can use that too.

Protein scoops and some gym equipment
Protein scoops and some gym equipment

Now let’s talk a bit about handling the product. If you want your whey protein to retain quality for as long as possible, always use dry utensils and keep the milk or water you add the powder to away.

Occasional use of a slightly wet teaspoon probably won’t cause the substance to go moldy, but you never know. Same thing with those few drops of water when preparing the protein shake. If it happens once or twice, it’ll probably be okay. But if it becomes a regular occurrence, that powder likely won’t survive to the date on the label.

Once you’ve mixed your whey protein with the liquid of your choice, it’s best to drink it right away.

If you need some liquid power to supply your workouts or a post-workout shake, it’s best to take the ingredients separately and prepare everything in the locker room. That’s especially true in the summer, as you definitely don’t want to have a prepped protein shake sit in the car when the weather is sweltering.

Generally speaking, you can refrigerate a mixed protein shake for up to two days, but I’ve never heard of anyone doing that regularly or even occasionally.

In a Nutshell

  • Keep whey protein in a dry place away from heat
  • Whey gradually degrades in quality, so it might not taste that great after a few months past the date on the label
  • “Expired” whey protein might have slightly less nutritional value than one that’s in date has, but it’s generally safe to eat