ABSTRACT
Partial dehydration in high-water-content foodstuff such as fruits, vegetables, and juices has become of great interest in order to diminish water activity and thus prolong shelf life during refrigeration. In this chapter, we are going to describe some of the pretreatments that can be used before refrigeration to accomplish the preceding
10.1 Introduction .................................................................................................. 197 10.2 Pretreatments for Fruits and Vegetables ....................................................... 198
10.2.1 Partial Air-Drying ............................................................................ 199 10.2.2 Heat and Mass Transfer Characteristics in Air Partial
Dehydration .................................................................................... 200 10.2.2.1 Surface Area ......................................................................200 10.2.2.2 Temperature .......................................................................200 10.2.2.3 Air Velocity ........................................................................ 201 10.2.2.4 Dryness of Air ................................................................... 201 10.2.2.5 Atmospheric Pressure and Vacuum ................................... 201 10.2.2.6 Evaporation and Temperature ............................................ 201 10.2.2.7 Time and Temperature ....................................................... 201
10.3 Osmotic Dehydration ....................................................................................202 10.3.1 Mass Transfer Characteristics during Osmotic Dehydration ...........206 10.3.2 Formulation of Food .........................................................................207 10.3.3 Osmotic Solution Recycling .............................................................207 10.3.4 Solution Concentration Restoring .....................................................208 10.3.5 Microbial Contamination of the Solution .........................................209
10.4 Juice Concentration ......................................................................................209 10.4.1 Evaporation .......................................................................................209 10.4.2 Hyperžltration and Ultražltration .................................................... 210
References .............................................................................................................. 211
goals. In order to get a better understanding of the subject, we are going to approach it considering žrst, the possible pretreatments for fruits and vegetables, and then the available methods for juice concentration.
