This means that for the first time the high pressure treatment of foods within the packaging process can be seen as a viable option. As one of the first packaging manufacturers worldwide to master the process, Multivac can offer it not only for vacuum- but also for MAP packs. The necessary technical innovations have already been filed for patent.
A clear trend towards more naturalness combined with ever increasing requirements by the supervisory authorities for the exclusion of harmful microorganisms from foods has meant that the high pressure treatment of packaged foods is gaining in importance. With high pressure treatment packaged food is subjected for a sufficiently long period to a high pressure of up to 6,000 bar in a so-called autoclave, which is a lockable and gas tight pressure container. Through this reliable process microorganisms in the food such as listeria and salmonella are killed. As the process is conducted under ambient temperature, even heat-sensitive food products can be treated and this way be preserved for up to four times longer. At the same time the original nutritional value and taste remain nearly unimpaired.
Until now high pressure treatment was mostly carried out in a separate manufacturing stage. Moreover the manual loading of the high pressure container is not very efficient. With some new technical innovations, which have already been filed for patent, MultivaC has developed a pioneering solution for the line integration of high pressure equipment for the treatment of packaged foods. The solution comprises a high pressure unit (one ore more autoclaves), which has been developed by the ThyssenKrupp daughter company, Uhde High Pressure Technologies, as well as an automatisation concept to integrate the process into packaging lines which are laid out to meet the demands of the food industry. In addition Multivac offers a high pressure compatible packaging concept which makes the process suitable for even MAP packs, and it also offers a wide range of services within which customers can receive individually tailored advice and make use of testing facilities.
With the integration solution developed by Multivac the finished food packs are automatically loaded into the transport containers (patent pending) and, following the high pressure treatment in the autoclave, then automatically unloaded, dried, printed or labelled if required, and finally packed into cartons. "In this way, it is for the first time that we can process large, industrial scale production quantities fully automatically in a quasi continuous operation", says Tobias Richter, Product Manager in the Systems Business Group and responsible for high pressure equipment at Multivac.
In order to achieve as high a machine throughput as possible the available space in the autoclave must be used as intelligently as possible. "Since the high pressure equipment is round for reasons of optimising the distribution of pressure forces, the loading pattern also has to be designed accordingly", says Richter. With a favourable pack shape it is possible to handle two to four tonnes of packed food per hour in the high pressure equipment. With its extensive know-how and comprehensive range of services Multivac supports its customers in choosing the optimum pack shape, in selecting the packaging materials for the pack and in carrying out the high pressure process. As part of this there is the construction of the necessary test facilities with Uhde as well as the provision of a wide range of advisory services.
As the only manufacturer to date worldwide, Multivac has also mastered the process for MAP packs. The packaging specialist from the Allgäu designs not only high pressure stable MAP pack concepts but has also in cooperation with Uhde High Pressure Technologies optimised the HPP unit itself so that the high pressures in the autoclave are relieved in a controlled manner. "With the help of so-called 'holding torque' we create short rest periods in which the polymer can regenerate. In this way the packaging material is stressed considerably less and retains its functionality even after the high pressure treatment", says Tobias Richter. Patent applications for the process have been filed.