THE EFFECT OF STRUCTURE AND IMBIBITION MODE ON THE REHYDRATION KINETICS OF FREEZE-DRIED CARROTS

摘要

Fruits and vegetables (F&V's) are an important source of (micro)nutrients and sustained dietary intake has been associated with beneficial health effects. Drying of F&V's is an important process in prolonging shelf-life and provide convenience to the consumer;" Market growth is however impeded by the relative poor textural quality of rehydrated F&V's, which is not seen yet as a fair compromise with respect to convenience. Due to its cost-effectiveness, air drying is currently the dominating technology, although product quality is significantly compromised with respect to appearance, nutritional value and flavor. Furthermore, rehydration rates tend to be slow. Freeze drying yields high quality products which also rehydrate more rapidly, albeit at larger operational costs. Freeze-dried F&V's still tend to be frail and upon rehydration the texture of the native products is still not fully recovered. Current approaches to understand and improve the quality of freeze-dried food products do so by balancing the rehydration rate and final texture in an empirical manner. A prerequisite for more rational approaches is availability of models describing rehydration behavior of porous food materials based on physical principles. To this date, most physical modeling approaches make simplifications regarding the multiscale structure which is however inherent to F&V's.