Gemini said
It’s a common concern for winemakers: you open your package of malolactic (ML) bacteria and find that the ice pack has melted and the packet feels warm. While it’s natural to worry about the health of your culture, there is usually no need for alarm.
Here is a guide to help you understand why your ML bacteria is likely still in great shape and how to store it correctly.
"Help! My Bacteria Arrived Warm"
If your malolactic bacteria arrived and the container isn't cold to the touch, don't panic. Most modern malolactic cultures (specifically those produced using the MBR™ process) are much heartier than they used to be.
While we ship these cultures with ice to provide a buffer against extreme heat, they are designed to withstand moderate temperature fluctuations during transit without losing their effectiveness.
The Science: Why They Are Still Good
Most of the malolactic bacteria we carry are produced using a proprietary "MBR" (Mutations, Selection, and Adaptation) process. This method creates bacteria with very low water activity, making them significantly more stable than liquid or frozen formats.
Temperature Tolerance: Research shows that these cultures can withstand temperatures up to 86°F (30°C) for as long as 48 hours with virtually no loss in viability.
Shelf Stability: In fact, sealed packets can often remain at ambient room temperature (under 77°F) for up to three weeks without a critical loss of cell count.
Performance: Even if the packet feels warm, the bacteria's ability to complete malolactic fermentation (MLF) remains intact as long as the exposure was short-term.
When Should I Be Concerned?
You should only be concerned if the bacteria was exposed to extreme heat (well over 100°F) for multiple days, or if the internal seal of the packet has been compromised. If the package arrived bloated or damaged, please reach out to our support team.
Storage Best Practices
Once your bacteria arrives, the goal is to "put them to sleep" to preserve their shelf life until you're ready to inoculate.
Refrigerate or Freeze Immediately: As soon as you receive your package, place the bacteria in the fridge or freezer.
Short-Term Storage (<18 Months): Store at 39°F (4°C) in a standard refrigerator.
Long-Term Storage (>18 Months): Store at 0°F (-18°C) in a freezer. This will ensure the highest possible cell count for the duration of the product's shelf life.
Keep it Sealed: Do not open the foil packet until the moment you are ready to add the bacteria to your wine.
Pro-Tip: Don't Forget the Nutrient!
Success with MLF isn't just about the bacteria; it’s about the environment. If you are worried about the health of your culture or if you are working with a difficult wine (low pH or high SO2), we highly recommend using an ML-specific nutrient like Acti-ML to give your bacteria the best chance of success.
Still have questions? If you have concerns about a specific shipment or a stuck fermentation, our tech team is here to help you troubleshoot. Happy winemaking!