Shrinkage during convective drying of whole rose hip (Rosa rubiginosa L.) fruits

Volume and area shrinkages occur during food dehydration. The food behaviour must be characterized not only for using in process and equipment simulation models but also to evaluate the final quality of the product. No litature reports were found on the rose hip behaviour. After removing the peduncles, whole fruits were dehydrated in heated air at temperatures of 50, 55, 60, 65, and 75degreesC, air velocities of 1, 2, 3 , 5 m/s, and air relative humidities of 5 and 50%. Volume changes were evaluated by picnometric techniques and with geometric measurements by micrometer and superficial area from geometric measurements. In agreement with previous reports on other foods, volume and area changes do not depend on dehydration operating variables. A linear relationship was found between the dimensionless volume change and the moisture content of the partially dehydrated fruits. The area depended on moisture according to a third-grade polynomial.