Nitrogen-frozen bacteria: GEA technology boosts active cell count, cuts fermentation costs

29 Nov 2019 --- By freezing bacteria into pellets before drying, GEA is aiming to elevate the utility of fermentation lines, while reducing costs. The company’s new nitrogen freezing pilot pant for bacteria targets dairy and food processors, as well as suppliers of probiotic products, who use live bacteria as part of their production process. The technology tackles some typical problems of production processes using live bacteria, while raising the active cell count of cultures.

Traditionally, producers keep their own strains of bacteria and transfer them from one batch to the next. However, as more specialized strains of bacteria have emerged, so too the need to distribute them more widely. This is typically done by freezing them to -50° Celsius and then storing them under temperature-controlled conditions until they are required. However, this requires a continuous cold chain, which might not be a problem in more developed countries, but challenging elsewhere.

For this reason, freeze-dried bacteria have become popular because they can be transported and stored at ambient temperature and rehydrated as required. But, freeze-drying bacteria is a long process and can be expensive. 

GEA’s technology freezes the bacteria droplets using a liquid nitrogen bath outside the freeze dryer.GEA’s technology aims to overcome such hurdles with a different approach. It freezes the bacteria droplets using a liquid nitrogen bath outside the freeze dryer then dries the pellets via the standard procedure.

The company notes how the method has many significant advantages. 

• Rather than freezing all of the bacteria in a single batch, it can be collected from a continuous stream which improves flexibility and equipment utilization. 
• Fermentation and freeze-drying are separate, so the freeze dryer does not need to be available when the product is frozen: bacteria can be stored at -50°C until it is required.
• The bacteria cell count resulting from this process is nearly double that of traditional freeze-drying techniques.
• Frozen pellets dry much quicker than bacteria in slab form; therefore the lyophilization process is also faster, typically 24 to 36 hours compared to up to 72 hours.

“Although there is a cost for the liquid nitrogen, this is more than offset by the optimized utilization of the freeze dryer,” explains Morten Pedersen, Area Sales Manager for GEA Process Engineering. “Freeze dryers are expensive so we need to make sure customers are getting the best possible output from them.”

Regarding the higher cell count from this technique, Morten states, “Bacteria that is frozen quickly via liquid nitrogen and dried in this way, is retaining twice as many viable cells than other techniques. This product is more effective than other options and, ultimately, reduces the customer’s costs.” 

The new pilot plant has a simple design, is easy to use and can be cleaned in place. “We are absolutely committed to this technology and want our customers to have the opportunity of trying it out for themselves in their own factories,” says Morten. “The results already seen with this new pilot plant are impressive, and we’re confident that our customers will also be delighted with the results.”

The GEA nitrogen freezing pilot plant will be on display at stand 6F141 in Hall H6 at the upcoming Food Ingredients Europe Exhibition (FiE) in Paris from December 3 to 5. 

Edited by Laxmi Haigh