Every morning, my husband makes a smoothie.
He throws frozen berries straight from the freezer into the blender, adds some yogurt or milk, a banana, maybe a little honey, and blends everything together.
I’ve always watched him do one thing that makes me uncomfortable.
He doesn’t rinse the frozen berries first.
When I mentioned it, he wasn’t worried at all.
His argument was simple:
“They’re frozen. Freezing kills bacteria.”
It sounded reasonable at first.
After all, freezing preserves food. We freeze meat, vegetables, fruit, leftovers, and all kinds of other foods specifically to make them last longer.
So I started wondering whether I was being overly cautious.
Should frozen berries really be rinsed before going into a smoothie?
Does freezing actually kill bacteria and viruses?
And if the berries are going directly into a blender without being cooked, is there a food-safety issue?
After looking into the science and food-safety guidance, the answer was much clearer than I expected.
My husband was right that freezing preserves berries—but he was wrong that freezing reliably kills harmful germs.
And there’s an important distinction between rinsing berries and actually making contaminated frozen berries safe to eat.
First: Freezing Does Not Mean Sterilizing
This is the biggest misconception in our kitchen.
Freezing and sterilization are completely different things.
Freezing slows or stops the growth of many microorganisms, which is why frozen foods can remain usable for long periods.
But freezing does not necessarily destroy the microorganisms already present.
The FDA specifically warns that freezing preserves berries but generally does not inactivate viruses such as hepatitis A virus and norovirus.
The FDA also explains that many kinds of bacteria can survive freezing temperatures. If enough bacteria survive in a frozen food, the food can still cause illness unless it is subsequently cooked sufficiently to kill them.
So my husband’s statement:
“Freezing kills bacteria.”
is simply too broad.
A more accurate statement would be:
“Freezing can preserve food and stop or slow microbial growth, but it doesn’t reliably eliminate all harmful microorganisms.”
That’s a very different thing.
Why Frozen Berries Deserve Special Attention
You might wonder why we’re talking specifically about berries.
After all, frozen vegetables and other foods are also exposed to potential contamination.
The reason is that berries have been associated with foodborne outbreaks.
The FDA has documented outbreaks of hepatitis A and norovirus associated with both fresh and frozen berries.
Berries can become contaminated at different points along the supply chain.
Possible sources include:
- Contaminated agricultural water
- Inadequate sanitation
- Contaminated surfaces
- Poor hand hygiene
- Handling during harvesting
- Processing and packaging
And because berries are often eaten without cooking, any contamination can potentially reach the consumer.
That’s particularly relevant to smoothies.
A smoothie isn’t cooked.
The blender doesn’t magically make contaminated food safe.
It simply breaks the berries into smaller pieces.
“But They’re Frozen!”
That was exactly my husband’s argument.
And I understand why it sounds convincing.
When we think of freezing, we think of preservation.
A freezer stops food from spoiling quickly.
It prevents many microorganisms from multiplying.
But stopping growth isn’t the same thing as killing everything that’s already there.
Imagine putting a contaminated berry into the freezer.
The cold environment can prevent or greatly slow microbial growth.
But some microorganisms can survive the freezing process.
When the berry eventually warms up, surviving organisms may still be present.
That’s why frozen foods aren’t automatically sterile.
The FDA’s food-safety guidance specifically states that many types of bacteria can live even at freezing temperatures.
So the freezer is a preservation tool.
It isn’t a sterilization machine.
What About Viruses?
This is where the issue becomes even more important.
People often think of food poisoning as something caused only by bacteria such as Salmonella or E. coli.
But viruses can also cause foodborne illness.
The FDA specifically identifies hepatitis A virus and norovirus as concerns associated with berries.
And freezing doesn’t reliably destroy those viruses.
In fact, the FDA’s berry safety strategy was developed partly because of repeated outbreaks involving fresh and frozen berries.
This isn’t merely a theoretical concern.
There have been real outbreaks.
A Recent Example Shows Why This Matters
In 2024–2025, an outbreak of hepatitis A in the Netherlands was linked to frozen blueberries.
According to a CDC-published investigation released in 2026, 24 people became ill, and epidemiological evidence combined with detection of the outbreak strain in frozen blueberry samples pointed to a particular frozen blueberry product as the likely source. Eight of the affected people were hospitalized, although no deaths occurred.
That’s an important reminder:
Frozen fruit can remain associated with a foodborne-virus risk.
Freezing didn’t magically eliminate the hepatitis A virus in the implicated berries.
And that’s exactly why the argument that “it’s frozen, so it’s safe” isn’t sufficient.
So Should You Rinse Frozen Berries?
Here’s where things get a little more complicated.
It would be tempting to say:
“Just rinse every frozen berry before putting it into your smoothie.”
But rinsing isn’t a perfect safety solution.
The FDA recommends washing produce thoroughly under running water before preparing or eating it, while also explaining that washing can reduce bacteria but won’t eliminate all bacteria.
So rinsing can be useful for removing dirt and reducing some surface contamination.
But it doesn’t turn contaminated berries into guaranteed-safe berries.
That’s an important distinction.
Rinsing is not the same as disinfection.
And You Shouldn’t Wash Berries With Soap
If you’re thinking:
“Then I’ll just wash the berries really well with soap.”
Don’t.
The FDA specifically advises against washing fruits and vegetables with soap, detergent, or commercial produce washes.
Produce is porous, and soap or detergent can be absorbed.
Plain running water is the appropriate approach for washing produce.
But again, washing reduces contamination rather than eliminating every possible pathogen.
What About Frozen Berries Labeled “Ready to Eat”?
This is an important detail.
Some packaged fruits may be labeled as ready to eat or may have been processed under conditions intended to reduce contamination.
Follow the package directions.
If the package specifically says the berries are ready to eat, there may be no need for additional washing.
The FDA notes that packaged produce identified as pre-washed or ready-to-eat can generally be used without further washing, provided it doesn’t come into contact with contaminated surfaces or utensils.
So don’t automatically assume that every frozen berry product needs to be treated exactly the same way.
Read the package.
The Bigger Issue With Smoothies
Here’s why I became more concerned about our morning smoothies.
When we eat berries in a baked dessert, the berries may be exposed to significant heat.
That changes the food-safety picture.
But a smoothie is completely different.
The berries go:
Freezer → blender → glass → mouth.
There is no cooking step.
The blender doesn’t reach a temperature high enough to reliably kill pathogens.
It just physically breaks the berries apart.
So if contaminated berries go into the blender, the resulting smoothie can contain the contamination throughout the drink.
That’s why using raw frozen berries deserves more thought than using frozen berries in a recipe that will be thoroughly cooked.
Could Rinsing Spread Contamination?
It can if you’re careless.
Washing produce isn’t inherently dangerous, but splashing contaminated water around your kitchen can create cross-contamination.
If you rinse frozen berries in the sink, clean the sink and surrounding surfaces afterward.
Wash your hands before and after handling the berries.
Don’t let the berries touch surfaces that are used for ready-to-eat foods.
The goal is to reduce contamination rather than move it around the kitchen.
What I Would Do With Frozen Berries for Smoothies
If I’m using frozen berries in a smoothie, I’d start with the simplest safety measure:
Check the package for recalls or preparation instructions.
This is especially important because food-safety problems can be associated with specific batches or suppliers.
If there is a recall, don’t try to rescue the berries by rinsing them.
Don’t eat recalled food.
For example, during the 2023 U.S. hepatitis A outbreak, FDA and CDC advised consumers not to eat the implicated recalled frozen strawberries.
A recall means the product has been identified as presenting a food-safety concern.
Washing isn’t a substitute for following a recall notice.
What If the Berries Look and Smell Fine?
Unfortunately, appearance isn’t enough.
A contaminated berry may look completely normal.
It may smell normal.
It may taste normal.
That’s true of many foodborne pathogens.
You can’t reliably inspect a berry and determine whether it contains hepatitis A virus, norovirus, or certain bacteria.
That’s why safe handling practices and reliable product information matter.
Don’t use appearance as your only safety test.
Does Organic Mean Safer?
Not automatically.
Organic berries can be nutritious and perfectly safe, but organic certification doesn’t mean the berries are immune to contamination.
The FDA has investigated outbreaks involving imported organic strawberries.
In 2023, an outbreak of hepatitis A was linked to frozen organic strawberries imported from Mexico.
The lesson isn’t “never buy organic.”
The lesson is:
Organic doesn’t mean pathogen-proof.
The same basic food-safety principles still apply.
What About Washing the Berries While They’re Frozen?
This can be awkward.
Frozen berries can stick together, and water can quickly turn them into a cold, wet mass.
If you’re going to wash berries, handling them according to the package directions is best.
You don’t need to aggressively scrub them.
Produce washing is primarily about rinsing away dirt and reducing some surface contamination.
And remember:
Rinsing doesn’t make a recalled product safe.
Should You Thaw the Berries First?
Not necessarily.
If you’re making a smoothie, frozen berries can go directly into the blender if the product instructions allow it.
Thawing isn’t what makes berries safe.
And thawing them does not kill pathogens either.
In fact, once food warms, microorganisms that survived freezing may become capable of growing again if conditions allow.
So don’t thaw berries on the counter and assume that they’re becoming safer.
They’re not.
The Best Food-Safety Question Isn’t “Frozen or Fresh?”
This whole discussion taught me something important.
I had been thinking about the problem as:
Fresh berries = potentially unsafe.
Frozen berries = safe.
But that’s too simplistic.
The better questions are:
Where did the berries come from?
Were they processed properly?
Are there any recalls?
Does the package provide preparation instructions?
Are they being eaten raw or cooked?
Are they being handled hygienically?
Those questions give you a much more realistic picture of risk.
What About Cooking the Berries?
Cooking is a much more effective way of reducing microbial risk than simply freezing or rinsing.
The FDA notes that thorough cooking kills harmful bacteria and reduces the risk of illness.
That’s why frozen berries used in a cooked pie, sauce, or other thoroughly heated dish are different from frozen berries thrown directly into a cold smoothie.
If you are particularly concerned about the safety of frozen berries for a raw preparation, cooking them first is a more robust pathogen-control step.
Of course, cooking changes the berries.
They won’t remain cold, firm, and fresh-tasting.
But from a food-safety perspective, heat is doing something that freezing does not reliably do.
What About Children, Older Adults, or People at Higher Risk?
Food-safety decisions can become more important for people who are more vulnerable to serious foodborne illness.
Young children, older adults, pregnant people, and people with certain underlying health conditions can face greater consequences from some foodborne infections.
If you’re preparing smoothies for someone in a higher-risk group, it’s especially reasonable to follow official product instructions, recall notices, and conservative food-safety practices.
When in doubt, choose a preparation method that includes a validated cooking step.
My Husband’s Argument Was Half Right
After researching this, I had to give my husband a little credit.
He wasn’t completely wrong.
Freezing does preserve food.
It can slow microbial growth dramatically.
That’s one of the reasons frozen foods can last so long.
But he was wrong about the second part.
Freezing does not reliably kill all bacteria or viruses.
The FDA explicitly says that many bacteria can survive freezing, and freezing generally doesn’t inactivate viruses such as hepatitis A and norovirus.
So his argument was based on a real fact—but he took that fact one step too far.
The Answer Isn’t Simply “Rinse Them”
I also realized that I wasn’t completely right either.
My instinct was:
“He doesn’t rinse them, so they must be unsafe.”
But that’s also too simplistic.
Rinsing can reduce some contamination on produce, but it doesn’t eliminate all pathogens.
And if a frozen berry product has been recalled because of contamination, rinsing it isn’t an acceptable fix.
So the most accurate answer is somewhere in the middle.
Don’t assume frozen means sterile.
But also:
Don’t assume rinsing makes frozen berries completely safe.
A Safer Smoothie Routine
If you regularly make smoothies with frozen berries, a few habits can make sense.
Check the packaging
Look for storage and preparation instructions.
Check for recalls
Especially if you’re using berries that have been stored for a long time.
Keep frozen fruit frozen
Don’t repeatedly allow the berries to thaw and refreeze.
Wash your hands
Clean hands before preparing food are one of the simplest food-safety measures.
Keep equipment clean
Wash the blender jar, lid, blades, and utensils properly after use.
Prevent cross-contamination
Don’t let frozen fruit or its packaging contact dirty surfaces.
Don’t rely on smell or appearance
Contaminated food can look perfectly normal.
Follow specific package instructions
If the manufacturer says the product needs to be cooked, don’t use it raw in a smoothie.
Consider cooking if you want a stronger pathogen-control step
Thorough cooking is much more effective at killing harmful microorganisms than freezing or rinsing.
Frequently Asked Questions
Does freezing kill bacteria in berries?
No—not reliably. Freezing can stop or slow bacterial growth, but many bacteria can survive freezing temperatures.
Does freezing kill hepatitis A virus?
Freezing does not reliably inactivate hepatitis A virus. The FDA specifically warns that freezing generally does not inactivate viruses such as hepatitis A and norovirus.
Should frozen berries be washed before eating?
Follow the package instructions. Washing produce under running water can reduce some surface contamination, but it does not eliminate all pathogens.
Can I wash frozen berries with soap?
No. The FDA advises against washing produce with soap or detergent.
Can frozen berries make you sick?
Yes. Frozen berries have been associated with foodborne outbreaks, including hepatitis A and norovirus outbreaks.
Are frozen berries safe in smoothies?
They can be, but they are being eaten without a cooking step, so don’t assume freezing has eliminated pathogens. Follow package instructions and check recall information.
Does blending kill bacteria?
No. A household blender is not a validated pathogen-killing step. It breaks food apart but does not reliably heat it enough to destroy pathogens.
What should I do if my frozen berries are recalled?
Don’t eat them, even if you plan to wash or cook them. Follow the recall instructions for disposal or return.
The Final Verdict: Who Was Right?
After all this, I had to admit that neither of us had the complete answer.
My husband was wrong to say:
“Freezing kills bacteria.”
Freezing preserves food, but it does not reliably eliminate all bacteria, and it generally doesn’t inactivate viruses such as hepatitis A and norovirus.
But I was also wrong if I thought:
“Just rinsing the berries makes them completely safe.”
Washing can reduce some surface contamination, but it can’t guarantee that all harmful microorganisms are gone.
And that’s the most important lesson.
Frozen doesn’t mean sterile.
Frozen berries have been involved in real foodborne outbreaks, including a hepatitis A outbreak linked to frozen blueberries in the Netherlands in 2024–2025.
So these days, when my husband reaches into the freezer for the berries, I don’t simply ask whether they’re frozen.
I look at the package.
I check the instructions.
I pay attention to recalls.
And I remember that a freezer is designed to preserve food—not sterilize it.
If the berries are intended to be eaten raw, such as in a smoothie, that’s worth remembering.
Because sometimes the simplest kitchen assumptions are the ones that deserve a second look.