A recent consumer report cited microwave ovens as being one of the most common electrical
appliances in use today, despite the fact that many foods cannot be satisfactorily cooked using this
technique. Some new software produced in the Department's Electricity Utilisation Group will help
manufacturers produce microwave ovens and package containers that are better at cooking some of the latest
products from the food industry.
 Some producers of 'ready-to-microwave' meals have now introduced so called 'active
packaging'.This involves coating the inside of a conventional cardboard food-container with a thin film of
metal. The metallic layer can then act as a reflector, or it can absorb microwaves and become an additional
heat source to warm up food.
How the coatings act depend on their thickness and the type of metal used. By putting metallic layers down in
specific patterns, the component items of a 'ready meal' can be differentially heated. Thus meat can be
cooked more than the sauce adjacent to it. This clever business is already going on (check the insides of
your food containers for metallic layers) but as yet, the packaging designs are being formulated on a trial
and error basis.
Richard Ehlers, a research student with Dr Ricky Metaxas, has now developed some software to analyse the
heating patterns created by active packaging used in conjunction with microwave ovens. This predictive
modelling tool can be used to assess how different packaging designs will affect the heating up of the food.
Information about how the use of different types of metal and different thicknesses of coatings will affect
the heating process can be determined.
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Numerical prediction of heating pattern (left) produced by packaging shown above, compared
with thermal image produced experimentally (right). Click on images for larger view.
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As well as leading to changes in packaging design, this could also be used to improve the design of microwave
ovens. It even seems likely that we will be able to produce crisp tasty Pizzas using microwave heating with
this technology. Now that's something to look forward to.
The software is to be transferred initially to Unilever who sponsored the project. For further information,
please contact Dr Ricky Metaxas.
The development of software to analyse the hot spots in both domestic and industrial microwave ovens, on
which this work has been based, was described in Enginuity 5. This provides manufacturers with
a design tool to produce ovens giving more uniform heating, without the need to build a number of expensive
prototypes. |
