Pasteurizers are substantially used to kill off bacterial loads in pasta products through pasteurization treatment, this term giving the machine its name, where the products undergoes a thermal treatment in which the temperature of the product is sent about 70° C for a determined period of time.
The treatment, which cannot take place in a dry environment due to product damage, must be carried out with humidity, water vapour, so that the surface of the product does not undergo dangerous surface tension.
Furthermore, the presence of water vapour increases the thermal exchange and thus the effectiveness of the treatment, facilitating the surface gelatinization of the starch found in pasta, bringing out the colour and creating a shiny gloss on the product’s surface, which increases the consistency and thus resistance to the product becoming cooked.
Therefore the presence of water vapour is fundamental during the pasteurization process.
In the SCLV family of plants, the pasteurization process in carried out through saturated vapour injection in the pasteurization chamber, which has the double role of raising the product temperature and maintaining the correct level of humidity. The injected vapour is very near saturation conditions and therefore the amount of thermal energy transmitted to the product must be such that it doesn’t condense the vapour. One can deduce that only a small part of the thermal energy of the vapour is used, while the majority is expelled through suction hoods placed at the entrance and exit of the pasteurization chamber. For this reason, the vapour used during the process is called wasted vapour, based on the fact that it cannot be reused.
In order to compensate for this “inconvenience”, the vapour is overheated, version HT, in such a way that its internal energy is remarkably above that of saturation, but seeing that the process is taking place at atmospheric pressure, only part of this energy is actually used, based on the fact that the thermal conductivity coefficient undergoes a noteworthy reduction, partially cancelling out all the advantages derived from overheating. This particular method, notwithstanding this defect, is used above all in the treatment of high-yield fresh filled pasta when the quantity of filling is much greater than that of the pasta. As a matter of fact, when overheated vapour is applied, part of its energy is used to evaporate the humidity found in the filling, which – seeing that it cannot be reabsorbed by the pasta – stagnates on the product’s surface. In this way, at the end of the process the product has a surface that is almost dry and free of surface water vapour, thus avoiding future problems in the processes that follow.
In order to compensate for this “inconvenience”, the vapour is overheated, version HT, in such a way that its internal energy is remarkably above that of saturation, but seeing that the process is taking place at atmospheric pressure, only part of this energy is actually used, based on the fact that the thermal conductivity coefficient undergoes a noteworthy reduction, partially cancelling out all the advantages derived from overheating. This particular method, notwithstanding this defect, is used above all in the treatment of high-yield fresh filled pasta when the quantity of filling is much greater than that of the pasta. As a matter of fact, when overheated vapour is applied, part of its energy is used to evaporate the humidity found in the filling, which – seeing that it cannot be reabsorbed by the pasta – stagnates on the product’s surface. In this way, at the end of the process the product has a surface that is almost dry and free of surface water vapour, thus avoiding future problems in the processes that follow.
Therefore, the choice of which plant to use must be made carefully, taking into consideration the various types of products to be treated and the goals that need to be reached, both in an aesthetic sense as well as those regarding microbiological requirements.
Our production of pasteurizers is framed around various design options where the pasteurization stage is coupled together with the quick dry and surface drying of the product, carried out in controlled temperature and humidity, eventually following by a cooling stage in order to lower the product temperature below the critical temperature for bacterial proliferation.
