Evaluation of a hybrid microwave process to replace malt kilning: feasibility and impacts on malt quality

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Malt kilning is a traditional hot-air drying process that is energy intensive, accounting for around 78% of primary energy usage in the malting process, a sector which is responsible for 300,000 t of CO2 annually in the UK alone. The sector needs to find energy efficient alternatives to this process, to reduce its carbon footprint. This project will bring together Boortmalt, the world's largest malting company, with academic partners specialising in malting and brewing science (Cook) and microwave process engineering (Dodds). Boortmalt is the largest malting company in the world with 27 malting plants across the globe and sustainability and innovation are two of its strategic pillars. The partners are already collaborating on a Boortmalt funded project to develop novel roasted malts and snack foods using hybrid microwave/ hot-air drying technology. This fluidised bed technology is being developed commercially with the expertise of the Microwave Process Engineering Team at Nottingham. It offers unique levels of control over temperature gradients within individual particles during drying. The present project targets applications where the survival of enzymes is of no importance and the aim is to produce novel products rather than to match existing specifications. The PhD studentship will evaluate the feasibility of applying the technology to the production of pale malts, which are used as base malts in brewing worldwide, with a global annual production of 24 million tonnes. This is a much more demanding application because the combination of air and microwave drying must be tuned in order to achieve a realistic throughput in continuous operation, whilst ensuring that key brewing enzymes (e.g. amylases, -glucanases) are not thermally denatured. Furthermore, other key specifications such as colour and flavour must be closely matched to conventional kilned products. The project will evaluate both the environmental impact, technical and economic feasibility of this approach working closely and benchmarking the proposed technology against the current state of the art.