Low-spore milk powders are difficult to produce consistently with the traditional operating schedule, and most milk spores and bacteria are in the milk coming into the plant. The dairy industry mainly deals with contamination from spore-forming thermophilic and mesophilic bacteria.
The Caloris system focuses on the evaporation part of the process, where the propagation of bacteria is done by growing biofilms. They stick to wet surfaces and grow a protective biofilm where it is a safe zone for bacteria to grow, develop and mature.
After about 10 hours, the biofilm reaches a mature level and releases live bacteria and spores into the milk product, effectively contaminating it.
Bruce Skinner of Caloris told DairyReporter that typical dairy evaporators run 20 hours continuously and then do a four-hour cleaning cycle. It’s common to use two feed preheaters because they are the first hotspot for biofilm growth.
One is run for the first 10 hours, than switched to the other, clean one for the second ten hours before both are cleaned in the four hour window. Skinner said it’s an effective method, but not fail-proof as the evaporator is still running for 20 continuous hours.
Caloris found that the simplest solution was to engineer a 10-hour product run followed by a two-hour cleaning cycle, on repeat. This gives it the same productivity schedule as conventional processes.
“We are not biochemists or biologists, we’re not focused on how can we prevent these bacteria from growing in the first place. They’re going to grow in these warm environments,” Skinner said.
Caloris decided to apply for the patent after supplying the Low-Spore Powder Production Process to two clients in 2017. Skinner shared that both clients have been “extremely happy and consistently producing low-spore powder” with the Caloris process.
Jim Peterson, president and CEO of Caloris, said "The Caloris Low-Spore Process is a valuable investment for processors looking to achieve the lowest possible spore levels in their produced powder. We are excited by the results we've seen with our customers and look forward to helping more companies improve their powder production systems."
Skinner said Caloris has looked into applying the technique at other plants, but adapting it to existing plants is challenging. Re-engineering it to clean in two hours can be difficult with older plants. Developing an evaporator from scratch is an easier engineering task.
“We were trying to create a process that was simple, yet following the customer’s routine and their current routine procedures for cleaning and production--just making it a simple process for them that is repeatable, day after day,” Skinner said.