Should frozen berries be rinsed before making smoothies?
It depends.
- If the berries are commercially packaged and labeled “ready to eat” or “washed,” most people use them directly from the bag.
- However, rinsing frozen berries can remove some dirt and reduce the number of microorganisms on the surface, although it does not guarantee they are safe from harmful germs.
Why are frozen berries sometimes a concern?
Frozen berries have been linked to outbreaks of:
- Hepatitis A
- Norovirus infection
These viruses can contaminate berries during harvesting or processing. Freezing does not kill these viruses.
Does freezing kill bacteria?
No. Freezing:
- Slows or stops bacterial growth.
- Does not reliably kill bacteria such as:
- Salmonellosis (caused by Salmonella)
- Listeriosis
- Escherichia coli infection
If these bacteria were present before freezing, many can survive frozen storage.
Is rinsing enough?
Rinsing:
- ✔️ Removes some dirt and surface microbes.
- ✔️ May slightly reduce contamination.
- ❌ Does not remove all bacteria or viruses.
- ❌ Does not make contaminated berries completely safe.
What is the safest option?
For people at higher risk, including:
- Pregnant women
- Adults over 65
- Young children
- People with weakened immune systems
The safest approach is to cook frozen berries before eating them. Heating them until they reach a boil for about 1 minute can inactivate viruses and kill harmful bacteria.
Practical advice
If you make smoothies with frozen berries:
- Buy berries from reputable manufacturers.
- Keep them frozen until use.
- If you choose to rinse them, use clean running water and wash your hands before handling them.
- If you or someone in your household is at high risk for foodborne illness, consider briefly cooking the berries and cooling them before adding them to a smoothie.
Bottom line
Your husband’s statement that “freezing kills bacteria” is not correct. Freezing preserves food by preventing microorganisms from multiplying, but it does not reliably kill bacteria or viruses. Rinsing can help reduce surface contamination, but it is not a guarantee of safety. For people at higher risk, cooking frozen berries before consumption provides the greatest protection.