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Radiofrequency pasteurization is a form of electromagnetic energy which can be used to heat packed foods in a homogeneous way. With this technology every part of the packed product can be heated with the same heating rate.
At radiofrequency pasteurization ions in the product are being set in motion. The movement of the ions sets water molecules in motion which in their turn produce warmth. The product is being placed between an electrode and the “earth”. The energy moves via air and packing material through the product and heats the product from within. Radiofrequency pasteurization can also take place under water; the use of demineralized water quickens the heating rate. Radiofrequency pasteurization uses electromagnetic radiation with frequencies of 13.56 MHz, 27.12 MHz and 40.68 MHz. The frequency influences the depth of impact in the product; the lower the radio frequency, the bigger the wave length, the deeper the impact. Radiofrequency pasteurization has an impact of approximately 10 cm. Micro-organisms and enzymes are being killed off by heating.
Radiofrequency pasteurization in the food industry is mainly applied for drying or thawing of products or for the final baking of bakery products. This technique can also be used for the pasteurization of fruit, packed foods and fluid foods. This way of pasteurizing can be used either for batch productions or continuous systems and is fit for packed and unpacked products. Though radiofrequency pasteurizing can be applied to batch as well as continuous systems, the continuous system is most suitable. The reason being that in continuous systems it is easier to reproduce a homogeneous heating than in batch systems.
During radiofrequency pasteurization the product is being heated. Therefor the quality of the product is comparable to conventional heating techniques.
Pros and Cons
- Suitable for foods up to 10 cm thick
- Low investment costs
- Faster heating than with conventional, indirect heating
- Homogeneous heating
- Little impact of heat on product
- No need for a heating medium (such as steam)
- Energy efficient
- Heating of viscous fluids and fluids with particles
- Risk of bending of product
- Control of temperature (difficult to measure)
- The form of the packaging can lead to non-homogeneous heating
Availability of machinery
The costs of a generator are approximately €1000 per kW. Total running costs: €0.05 per kg.
- Sairem: tests can be performed by Sairem or at the customers’ location. Heating or thawing in a continuous system or batch system up to 300 kg/hr.