Will a protein shake stay good in the fridge?


Protein shakes have become a popular dietary supplement for many looking to increase their protein intake. Typically made by blending protein powder with water or milk, protein shakes provide a quick and convenient way to get extra protein. However, like other prepared foods and beverages, protein shakes have a limited shelf life. So how long do protein shakes stay fresh in the fridge after mixing? Here is a detailed look at how long protein shakes last refrigerated and signs that your shake has gone bad.

How Long Do Protein Shakes Last Refrigerated?

The shelf life of a protein shake depends primarily on the ingredients. Here are some general guidelines for how long different types of protein shakes will last refrigerated:

Protein Shake Type Refrigerator Life
Whey protein shake made with water 3-4 days
Whey protein shake made with milk 2-3 days
Plant protein shake made with water 3-4 days
Plant protein shake made with milk 2-3 days
Premade protein shake bottle 3-5 days

As you can see, whey and plant-based protein powders dissolved in water tend to last a bit longer (3-4 days) compared to shakes made with milk which sour faster (2-3 days). Premade bottled shakes fall in the middle with an average fridge life of 3-5 days.

Now let’s look at the reasons why protein shakes spoil and how to tell if your refrigerated shake has gone bad.

Why Do Protein Shakes Go Bad?

There are a few main reasons why protein shakes spoil even when refrigerated:

1. Bacterial growth

Like any food product, protein shakes can grow bacteria over time. While chilling protein shakes helps slow bacteria growth, it does not completely prevent it. Even refrigerated, shakes can start developing mold, yeast, and harmful pathogens after several days.

2. Nutrient degradation

The proteins, vitamins, and minerals in protein shakes also slowly degrade with time. Refrigeration helps slow the breakdown, but cannot stop it completely. So the nutritional value of shakes declines each passing day.

3. Separation and curdling

The ingredients in a protein shake – especially in shakes containing dairy milk – also tend to separate and curdle as they sit. The proteins clump together while the liquid whey separates. This results in a lumpy, curdled texture.

4. Oxidation

Exposure to oxygen causes the fats and other compounds in protein shakes to slowly oxidize. This chemical change leads to stale, rancid odors and flavors.

So in summary, the main factors limiting the shelf life of refrigerated protein shakes are bacteria growth, nutrient loss, separation/curdling, and oxidation. But how can you tell when your protein shake has spoiled and should be thrown out?

Signs Your Protein Shake Has Gone Bad

Watch for these signs that indicate your refrigerated protein shake has spoiled and should not be consumed:

1. Sour smell

A rancid, sour, or “off” odor is one of the most telling signs of a spoiled shake. If your shake smells bad, it likely has growing bacteria or oxidation.

2. Change in texture

Separation, clumping, sliminess, or fuzziness are red flags. A spoiled shake may look curdled or have lumps or film floating in it.

3. Change in color

While natural separating may cause some light color changes, a dramatic shift to grey, yellow, pink, or green hues indicates mold growth.

4. Fizzing or bubbling

carbonation, bubbles, or fizz can signify fermentation and gas-producing bacteria. Shake shouldn’t bubble when you open it.

5. Mold growth

The presence of any fuzzy spots or mold – even just a few specks – means your shake is past safe consumption. Don’t take any chances with mold.

6. Sour taste

An overly tart, bitter, or acidic flavor can also betray spoiled protein. A major shift in taste is not normal.

So in summary, foul odors, changes in appearance, texture, or taste all signal that protein shake is no longer fresh and should be discarded. But what if your shake just looks a little separated – is it still safe to drink?

Is Separated Protein Shake Still Safe to Drink?

It’s common for protein shakes made with dairy milk to separate in the fridge over time. The milk fats and proteins clump together while the thin whey separates out. You’ll notice a thick, yogurt-like layer at the top with more liquid at the bottom.

This natural separation alone does not mean your refrigerated protein shake has spoiled. As long as it has been kept cold, is within the safe fridge life outlined above, and shows no other signs of spoilage like fouling smell or mold, a separated shake is still safe consume.

To mix it back together, simply shake the container vigorously before drinking. The clumps should redistribute evenly. You can also use a spoon or blender to fully reincorporate and smooth out the texture.

However, if your shake has taken on a cottage cheese consistency with very thick clumps or chunks, it is likely past its prime and best discarded.

How to Make Your Protein Shake Last Longer

Here are some tips to maximize the shelf life of refrigerated protein shakes:

– Start with fresh ingredients. Don’t use old protein powder or milk.

– Use water instead of milk for a longer-lasting shake.

– Refrigerate shake immediately after mixing. Don’t leave sitting out.

– Store in an airtight container to prevent oxidation and contamination.

– Avoid introducing bacteria – use clean blender and utensils. Don’t double dip spoons.

– Check seal on premade bottles to ensure no leaking or contamination.

– Keep fridge cold, below 40°F. Higher temps accelerate spoilage.

– Consume within 3-5 days for best flavor and nutritional value.

– Don’t mix in any extra fruits, veggies, or other perishable ingredients.

Following proper storage and handling methods can help extend the fridge life of your protein shakes by a day or two. But remember, even refrigerated shakes only last about 3-5 days at max before spoiling. So it’s always smart to make shakes fresh if stocking up for the week.

The Bottom Line

So when does a protein shake go bad? As a general rule of thumb:

– Whey or plant protein shakes made with water will last 3-4 days refrigerated.

– Shakes made with milk will keep 2-3 days.

– Premade bottled shakes last 3-5 days after opening.

Properly stored shakes remain safe if consumed within these time frames. However, for best taste and nutritional value, drink refrigerated shakes within 3 days.

Be on the lookout for signs of spoilage like sour smell, changed texture, mold, bubbling, or separation beyond the norm. When in doubt, remember this rule: if your refrigerated protein shake smells or looks bad, throw it out! Your body will thank you.


In summary, protein shakes can last 3-5 days when properly stored in the refrigerator. Separation alone doesn’t necessarily mean a protein shake is spoiled, but drastic changes in smell, texture, taste, or appearance likely mean it is past safe consumption and should be discarded. Following proper storage methods, using quality ingredients, keeping shakes chilled, and consuming within a few days are the best ways to extend the shelf life. But remember, even refrigerated protein shakes have a relatively short fridge life. Heed expiration or best by dates, and when in doubt, throw it out! Making shakes fresh is always the safest option.

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