Polytechnic University of Valencia Congress, 21st International Drying Symposium

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Modeling of atmospheric freeze-drying for sliced fruit
Akane Horie, Takashi Kobayashi, Kyuya Nakagawa

Last modified: 02-01-2019


A mathematical model that simulates atmospheric freeze-drying for apple slices was developed based on the classical mass and heat balance equations. When operated above the glass transition temperature, product shrinkage and micro-collapse due to the glass-rubber transition occurred. So, instead of assuming formation of dried and frozen zones, a glassy matrix with particular vapor pressure was assumed. Apparent vapor pressure of apple slices in the glassy state was experimentally measured and summarized in a diagram, and the values in this diagram were employed for the simulation. This approach well predicted drying kinetics with reasonable accuracy with simplified equations.

Keywords: atmospheric freeze-drying; food; mathematical model; glassy state


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