Are Malolactic Bacteria Still Viable After Shipping or Storage Problems?
Last updated: 6/2021
Applies to: Beverage producers who may have received malolactic bacteria with melted ice packs or who have stored them above recommended temperatures.
We recommend that our malolactic bacteria be kept cool. In fact, our recommendation is that bacteria be kept at -18ºC/0ºF for long-term storage. In the real world we know that bacteria can get warm during shipment and that not all wineries have perfect storage. The winemaker’s question then becomes: “How can I be confident that my malolactic culture is in good shape?” This is a good question and deserves a good answer.
MBR™ BACTERIA
Lallemand’s unique malolactic bacteria processing methods, called MBR™, have created important advantages. One advantage is that MBR cultures have very low water activity and are therefore more tolerant of moderate temperature variations when compared to other strain formats (frozen, liquid, etc.).
Lallemand ran studies to determine the effect of transport temperatures on MBR bacteria survival rate. Figure 1 shows the temperatures applied to bacteria during two simulated transport scenarios. The viability (survival rate), malolactic activity and water activity (directly linked to shelf life) were all tested. Results in both cases showed that MBR bacteria cell viability, malolactic activity, and shelf life were preserved.
Lallemand also tested the impact of moderate summer storage temperatures on MBR bacteria viability (see Fig. 2). The results showed good tolerance to short-term temperature exposure. Even after two weeks at 30°C(86°F) viability remained over 60% and over the guaranteed viable cell count of 10^11 CFU/g.
RECOMMENDATIONS
If despite our best efforts, the ice is melted and the container is not cold to the touch when your bacteria arrives, do not be alarmed. Lallemand’s proprietary manufacturing process means their bacteria are different. Provided that temperature variations are moderate (e.g. 30ºC/86ºF for less than 48 hours) viability should be excellent. In fact, sealed packets can be delivered and stored for 3 weeks at ambient temperature (<25°C/77°F) without critical loss of viability. So just put the bacteria in the cooler (-18ºC/0ºF is preferred, 4ºC/40ºF is acceptable) and keep it there until you need it.
Finally, we wish to emphasize that in spite of the superior temperature tolerance of Lallemand bacteria, cold is always preferred. To limit temperature variation, Lallemand ships MBR bacteria to Scott Laboratories by refrigerated transport. We ship to our customers overnight with icepacks. We ask that you store it cold. Such efforts will always have a positive impact on cell viability and malolactic activity.