The development of food simulants for microwave oven testing

The microwave heating characteristics of foods vary with temperature, chemical composition, physical state and geometry. The purpose of the food simulates reported in this paper is to provide heating loads that will enable reliable and reproducible characterization of the heating performance of microwave ovens (2.45 GHz), specifically when heating chilled convenience meals. An extensive literature search was done to identify food simulants that had been used to mimic the heating responses of foods when heated both conventionally and in microwave fields. Each prospective food simulant was initially assessed against a set of criteria that included ease of manufacture, stability and formability. Four meals were chosen to represent the range of chilled convenience meals available in the UK. Tests, using continuous fibre-optic temperature measurement during heating, indicated that the meals could be separated into two broad categories according to heating times, i.e. ‘slow’ and ‘fast’ responders. Food simulants were developed for the two food categories. A good match between food simulant and meal was achieved for the main indicators, i.e. temperatures at central and intermediate locations and weight loss. A close match (a difference of 2% between food simulant and meal) was achieved for the centre location, which is important, as this is often the coolest area in the meal after heating in domestic microwave ovens.