Because of its consistency and texture, raw meat is difficult to cut to specification at high volumes. Therefore, Tönnies needed to stabilize the product surface without freezing the entire portion. Doing this would allow the product to be labeled and marketed as fresh while also making the cutting process easier and uniform.
Tönnies first tried cryogenics to rapidly chill the meat, spraying liquid nitrogen on the product. Because the gas is sprayed, it was difficult to measure and could result in uneven freezing. Not fully satisfied with the cryogenic method, Tönnies decided to continue to evaluate alternatives. The company then discovered impingement freezing and cooling systems from FMC FoodTech for rapidly chilling products.
After comprehensive testing at FMC FoodTech’s laboratory in Helsingborg, Sweden, a procedure was developed to stabilize the outer surface of the meat product. In this process, the meat is frozen in FMC FoodTech’s Advantec freezer at an air temperature of -22 to -40oF (-30 to -40 oC) at very high air velocities. Using this method, an even ice zone forms on the outer surface of the product to a depth of 0.08 to 0.2". The ice zone reduced the enthalpy just enough to give an equalization temperature in the range of 32 to 36oF (0 to 2oC).
The impingement process also minimized dehydration and weight loss. However, to ensure that this was the right chilling method for Tönnies, the companies worked together to conduct testing at a Tönnies facility. There, testing showed the process did not affect the taste of the meat or the way the meat could be prepared for consumption, whether it was fried, grilled or roasted.
Satisfied with the results of testing, Tönnies moved ahead to full production levels. Currently, the company has five Advantec freezers that are used to produce approximately 4,400 lb/hr per line, for a total of 22,000 lb/hr. The freezers and their ability to rapidly chill meat products enable Tönnies to streamline its costs and generate more revenue with mass production capabilities.
In addition to meat, impingement freezing can be used on bread, eggs and candy products.