Mikrobiologische Grundlagen zur Kurzzeit-Sterilisation von Flüssigkeiten mit stückigen Anteilen

In comparison to autoclave sterilization aseptic processing offers several advantages, e.g. less damage of important ingredients or high energy recovery. New applications of aseptic packaging would be offered for food products which still are mostly heated in containers, such as food containing particles, e.g. soups, dessert or baby food. Therefore, the count reductions of bacterial spores in solid materials were investigated. Comparing the count reductions in the liquid and in the solid phase a distinct shifting to higher D-values in the solid phase was observed. These kinetic data of the count reduction of spores in solid food offered the possibility of calculating the necessary heating parameters for particulate food in continous flow-systems. Using the kinetic data for the destruction of 5 orders of magnitude in the case of Cl. sporogenes PA 3679 spores in the centre of the particles and the kinetic data of destruction of thiamine the heating time of meat particles was calculated i n dependence of the particle diameter: If a liquid phase of low viscosity is assumed or heat transfer is improved, e.g. in a scraped heat exchanger, preservation of high food quality up to diameters of 20 mm to 30 mm is possible. If a liquid phase of high viscosity is used, a heating process which preserves food quality in a wide range is only possible up to diameters of about 10 mm. Continuous heating of particles up to 30 mm reduces the quality of food in the same way as conventional sterilization process.