Yoghurt lovers are eager to purchase yoghurts with large fruit chunks without giving a thought to how complicated the manufacturing technology of such a product is. To produce yoghurt with large fruit chunks a specially profiled static mixer is necessary. Dr habilitated Jan Limanowski, from the Department of Process Engineering and Equipment of the UWM, has authored 4 patented designs of mixers used in the industry for mixing yoghurt, for the production of juices, carbonised water, tzatziki sauce and even chocolate.
The mixers he has patented are fixed in the pipe into which yoghurt and fruits are pumped using suitable lobe pumps. Both streams of ingredients are separated and combined again in successive profiles of the mixer, arranged in series in the pipe. Fruit chunks are not crushed by the mixer. In contrast, drinkable fruit yoghurt is produced with traditional rotary mixers.
– Where did the idea of a mixers for the production of yoghurt with fruits come from? In the 1990s, yoghurts with whole fruits appeared in Poland. No company in our country could produce yoghurt with a similar texture. Therefore, I decided to develop a static mixer which would retain fruit chunks in yoghurt. I developed a special method of selecting mixers (including the number of profiled elements) suitable for a wide variety of mixed ingredients – answers Prof. Jan Limanowski.
Prof. Limanowski patented the first design in 2002. Chocolate producers have become interested in the latest design, developed in the previous year. His mixers are used in many Polish food processing plants and in the USA, Germany, Russia, Romania and several other countries. To develop one patent takes about 2-3 years of work.
As Prof. Limanowski emphasises, the idea is the most important. There have been attempts to copy the shape of his mixer, but the copied device did not work properly.
– As it may seem, the mere copying of the shape of the mixer is not of much use, if one does not know the basics of fluid mechanics and hydraulics. One has to be able to predict phenomena occurring in the pipe when yoghurt is mixed with fruits and how the mixture will run down the surface of the mixer profiles. New problems arise all the time, e.g. how to mix ingredients differing widely in viscosity, density, or with differentiated rheological properties, so as to obtain a product with homogeneous quality – explains Prof. Limanowski.
– Currently, I am working on static mixers for granular materials. They are in ever greater demand – adds Prof. Jan Limanowski.