Studies in Food Process Engineering
Christian Trägårdh, Department of Food Technology

Food Engineering Introduction Research in food engineering is based on mathematical modelling of phenomena occurring in the food processing chain. Its scientific foundation is heat and mass transfer, fluid mechanics, rheology, biophysics, colloid science and physical chemistry, and understanding of compositional and structural complexities of foods and biomaterials. Own expertise is programmatically complemented by collaborations with other departments, in and outside LTH. The unit operations studied include membrane separations, mixing, emulsification, cleaning, osmotic dehydration, pulsed electric field application and comminution. Fluid mechanics in solutions and dispersions The core activities may be summarised as the study of fluid flow and its effects on the dispersion, aggregation, coalescence and adhesion of molecules, particles, drops and bubbles. Experimental techniques used include planar Laser induced fluorescence (PLIF), particle image velocimetry (PIV), phase Doppler anemometry (PDA), and thermal anemometry (CTA). Projects: (1) Powder-liquid mixing (2) Laminar mixing in static mixers (3) Flow and mixing in bubbly flow in stirred tan reactors (4) Impingement and IR heat transfer in baking (5) In-line rheology in food processing equipment Unit operations Membrane separations Membrane technology research is focused on pervaporation, crossflow microfiltration, ultrafiltration, nanofiltration and reverse osmosis and includes fundamental as well as applied research. Recovery of volatile organic compounds by pervaporation is studied with dilute aqueous multicomponent aroma solutions as a model. The research includes the effect of operating conditions such as feed flow velocity, permeate pressure and temperature on mass transfer and selectivity and the effect of hydrophobicity, and liquid molar volume of aroma compounds. Basic research concerning transport properties, characterisation and fouling of MF, UF and NF membranes are performed. Applied research and process development for the recovery of valuable substances, fractionation, concentration and purification using membrane technology is continuously carried out. Projects: (1) Separation of volatile organic compounds by pervaporation (2) Transport phenomena in nanofiltration (3) Process development for concentration and/or purification of liquid foods and food wastewaters Emulsification Concerns the dynamics of droplet formation in flow systems either this are at pore mouths of cross flow membranes or in elongational and turbulent flows in homogenizer heads Projects: (1) Membrane technology for the production of pectin-enclosed microemulsions (2) Foam formation using membrane technology (3) Flow characteristics and droplet break-up phenomena in high pressure homogenizers