title: Variable frequency microwave heating of food.
abstract: Industrial microwave food processing is universally based on single frequency microwave sources. With the emergence of variable frequency microwave ovens, it is possible to exploit the frequency dependence of a food's permittivity and/or choice of heating frequency, for example as a new route to achieving targeted heating. Variable frequency heating procedures are developed to overcome the geometry of a roughly spherical foodstuff dominating the heating pattern when heated in fixed frequency applicators. Target mean temperatures of 55, 75 and 90 degrees C within 2 minutes and without physical damage were set; means of 54.5 +/- 4.1, 75.1 +/- 4.7 and 87.6 +/- 3.5 degrees C respectively were achieved within the time constraint and with no major physical damage, based on combining 8 discrete frequencies between 2.4 and 6.2 GHz.
authors.affiliation: Unilever Research Colworth, Sharnbrook, Bedfordshire, UK.
authors.forename: J R
authors.initials: JR
authors.lastname: Bows
mesh_terms: D003296:Cooking; D005502:Food; D006358:Hot Temperature; D008872:Microwaves