Microwaves are well-established as sources of dry heat and are widely used in the home and some industrial applications. Traditional microwaves, based on magnetrons, however, suffer from non-uniform heating, and crust formation is difficult in commonly baked products such as bread (https://doi.org/10.1080/10408398.2017.1408564). Emerging solid-state microwave technology has the potential to overcome many of the disadvantages of conventional magnetron systems through their ability to provide uniform heating and modulate radiation intensity to satisfy specific product characteristics (https://doi.org/10.1016/j.jfoodeng.2018.04.009). Due their very recent emergence, only limited research has been carried out to-date, on establishing their performance characteristics and quantification of their quality and energy efficiency advantages over conventional magnetron technologies.
Hypothesis: Our hypothesis is that solid state microwave food processing (SSMP) can provide more uniform heating, better product sensorial and nutritional attributes and lower energy consumption and carbon footprint compared to conventional electrical resistance, gas or magnetron microwave heating and can provide a route to decarbonisation of domestic, commercial and industrial cooking and baking.
Main objectives:
a. Undertake a comprehensive literature review to develop in-depth understanding of baking processes in domestic, service and high volume industrial applications to enable characterisation and comparison of the performance of the SSMO against conventional technologies (electric resistance, gas and microwave-magnetron ovens) through extensive testing in the laboratory to establish benchmarks for the research outputs.
b. Undertake detailed investigations to explore the nutrient-retentive advantages of SSMOs for "temperature agile" controlled dehydration of fresh vegetables and fruit into snack forms against conventional dehydration processes (convection heating, freeze drying). Analyses of the effect of different dehydration methods on the nutritional qualities, structure (electron microscopy) and texture (crispiness, hardness, chewiness) of the product will be performed.
c. Undertake research on the ability of SSMO to recreate the physicochemical changes that happen during convection heating for bread making, such us the thermal setting of the structure, moisture loss, browning and crust formation in order to develop a product with a soft and elastic crumb texture, toasty (colour and acrylamide evaluation) and crunchy crust (electron microscopy and texture analysis) and roasty aroma (flavour and aroma analysis) which are very difficult to achieve with conventional microwave ovens.
d. Extensive simulation of solid state microwave food processing using appropriate software and techniques such as Multiphysics CFD with Radio Frequency modelling capabilities to be validated and calibrated with data from the experimental programme and used to investigate the influence of important design and control parameters on product quality and energy consumption.
e. Use the data from the tests and modelling to draw conclusions on the potential of SSMOs to provide improved product quality with lower energy input compared to conventional baking and cooking approaches and provide recommendations on areas and approaches for further improvement.