29D-11 |
Use of modelling to design and improve sterilization processes for food |
S. I. WIJNANT and P. S. R. Kosters. Process Innovation, TNO, PO Box 342, Apeldoorn, 7300 AH, Netherlands Sterilisation and pasteurization are common practise to prevent spoilage by bacterial spores. The heat treatment does also cause considerable sideeffects like decrease of net weight, enzymatic inactivation, chemical reactions and pressure built up in packaged food. As some of these effects are not desirable heat intensity should be limited to the minimum. Finding the right balance is hampered by the fact that each application is more or less unique. Experimental approaches by sending in data loggers are common. These tests are costly and tedious, and do not guarantee that the best solution is found, and each time a small variation is introduced with respect to product or process the whole exercise has to be repeated. TNO developed software to assist in the design of processes, and to evaluate new products and packages for the optimal heat treatment. The software tool is based on finite element methods. It predicts F0 values, pressure built–up and many more product parameters. The package contains an extensive database of product properties, and it allows shaping specific cans, jars or bottles. It can handle different types of autoclaves and has good graphical representations. The modelling of both conductive transfer and convective heat transfer is feasible. The application of the software has led to considerable capacity increase of sterilisation, reduction of off-spec products, significant savings in energy and water and increased process know-how. The programme is used for optimisation of the sterilisation process for products in glass jars in sterilisation towers. Optimisation took place with respect to process time, energy and water consumption. In addition important quality parameters are monitored such as death time curves (Fo-curves) temperature gradients in the jar walls and pressure inside the jar. Batch sterilisation is the oldest industrial preservative method and is widely used in almost all branches of the food industry. Better product quality will stimulate Product development for these processes.
Session 29D, Food Engineering: Thermal processes
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