What is Puffing?
Puffing technology used for drying biological materials (such as fruit and vegetables) requires innovative solutions. Such a unique technological installation is the MIVAC-3 vacuum rotary drum dryer.
In conventional (belt, drum or chamber) driers the final stage of the drying process, when material humidity is below 20%, is very slow (it takes up to a few hours) and the temperature of the dried material is high. This has a negative impact on the quality of the dried product – it loses its biologically active ingredients, and, most of all, vitamins. In contrast, drying fruit at reduced pressure, using a heating with a properly selected intensity of the electric field in the processing chamber allows for obtaining dried material with unique properties unattainable using conventional methods.
In the process carried out using the MIVAC-3 drier, all the negative factors affecting the quality of the product are eliminated. The drying process is very fast (usually takes 1-3 minutes) and additionally by maintaining low pressure the boiling temperature of water is significantly reduced and then the temperature of the dried material is much lower as compare to the conventional methods.
The Drying process
The drying process in the multi-drum drier is divided into three cycles.
1. In the first cycle the material placed in the drum with reduced pressure is heated by energy. In this drum the “puffing” process takes place. It is possible, by properly reducing the pressure in the dielectric drum, to dry the product quickly in conditions of heating the enriched material to relatively low temperatures (for example, 40-60°C), which allows to obtain a final product with excellent quality parameters. After the drying cycle carried out with adequately selected heating time, the drum filled with material is moved to a new position, outside the heating area.
2. In the second cycle the material in the rotating drum is still maintained at reduced pressure. In this stage the product stabilisation takes place. The evaporation still takes place so the temperature of the dried product decreases. Concentrated organic sugars harden stabilising the dimension of the dried material (cubes, flakes, etc).
3. The stabilisation is followed by the third cycle. The pipe with dried product is moved to a position in which the drum rotation is turned off, the inside of the drum is aerated and the dried material is removed from the drum. Then a new batch of material is introduced into the drum.
This procedure allows for simultaneous effecting of the described cycles in three pipes that periodically move inside the metal chamber. The drying process is carried out in one pipe, the product is stabilised in the second pipe, and the loading and unloading of material batches takes place in the third pipe. The described solution allows for optimal use of the energy generators – one set of such generators is used for heating the dried product successively in all pipes. This has a significant impact on the efficiency of the drying process carried out using just a single drier.
What is MIVAC-3?
The MIVAC-3 is a device that allows the drying process to be carried out on an industrial scale. It is equipped with complex automation systems and can be entirely operated by one person.
The original design of the drier and the specific drying technologies are protected by a patent application.