Results & Discussion
3.1 Drying experiments
Within this study it was found, that drying at low pressures (1 – 15 mbar) leads to a series of
drawbacks. At low pressure the coffee extract is undergoing a huge increase in volume during drying and
the resulting porous product cake has a very low thermal conductivity. Therefore the further drying
process is very slow. Furthermore, the final porous structure leads to a lighter, finer and glittering
product, which is undesirable with respect to present requirements for instant coffee appearance. Higher
system pressures (