Drying kinetics and color retention of dehydrated rosehips

Abstract

Freshly harvested rosehips (Rosa canina L.) were dehydrated in a parallel flow type air dryer at six air temperatures (30, 40, 50, 60, and 70degreesC) at air velocities of 0.5, 1.0, and 1.5m/s. Drying air temperature and velocity significantly influenced drying time and energy requirement. Minimum and maximum energy requirement for drying of rosehips were determined as 6.69kWh/kg for 70degreesC at 0.5m/s, and 42.46kWh/kg for 50degreesC, 1.5m/s. In order to reduce drying energy consumption, it is recommended that the drying air velocity must not be more than 0.5m/s and drying air temperature should be 70degreesC. In addition, the influence of drying air temperature and air velocity on the color of dried rosehip has been studied. Hunter L, a, b values were used to evaluate changes in the total color difference (DeltaE) on dried rosehips. 70degreesC drying air temperature and 1 m/s air velocity were found to yield better quality product.