LAUSR

Abstract Ice recrystallization occurring in vegetables during frozen storage causes changes in crystal morphology, and, thus, may affect product microstructure and quality. A mathematical model to describe the evolution of the crystal number density in frozen carrot tissue during dynamically changing temperatures was introduced to get a more comprehensive insight into microstructural changes. The model was based on a population balance equation that incorporated the ice crystal size distribution and a lumped heat transfer model, which assumed ice recrystallization via Ostwald ripening. Ice recrystallization was governed first by the dissolution of small crystals and then by redeposition at the surface of large crystals. This was observed mainly at the beginning of storage and gradually decreased as storage time proceeded. Sensitivity analysis showed that the activation energy is the most important model parameter, followed by the growth and dissolution coefficients. The model was validated based on measurements of the ice crystal size distribution and mean ice crystal size of carrot tissue to describe ice recrystallization during a two-month storage period under dynamically changing temperature condition. The PBE model was then applied to simulate ice recrystallization in carrots under industrial relevant conditions. The simulation results indicate that PBE model may be used to improve storage of frozen vegetables with respect to microstructure and quality.