Mild conductive drying of foods

Samenvatting (Engelstalig)

Drying operations in the food industry are responsible for a large share of the energy consumption. To reduce energy use we should shift towards a more efficient drying technology, for example replacing hot air drying by conductive drying technology. This could save up to 40% energy. However, mechanism-based knowledge to guide effective use of conductive drying approaches for high quality foods is lacking. The objective of this thesis was therefore to create insight in the drying mechanism of conductive drying for foods. This was realised by studying conductive drying of model foods (e.g. tomato paste, potato starch and spinach juice) in dedicated small-scale conductive drying devices. Experiments supported the development of kinetic models predicting quality changes and process models predicting drying kinetics. Finally, pilot-scale trials and a techno-economic assessment via a collaboration with ECN were carried out to compare the impact of different conductive drying technologies on product quality, energy consumption and costs. Guidelines are proposed to select the optimum conductive drying method balancing product quality, energy use and costs using tomato paste as an example.