Low-Temperature Vacuum Drying of Natural Gardenia Yellow Pigment

Abstract

The effects of operational parameters, that is, drying temperature, feed solution layer thickness, and level of vacuum, on product qualities and drying kinetics for low-temperature vacuum drying of Gardenia yellow pigment were studied. Temperature had the most significant effect on product quality and drying time. The optimal operating conditions to yield the best product quality were obtained as heating temperature, 35°C; layer thickness, 7 mm; and vacuum level, 0.09 MPa. Simulation results showed that the well-known Page model gave the best prediction. The effective diffusion coefficients for Gardenia yellow pigment solutions (20% wb) were estimated from the drying curves in the range 8.45 × 10−9 m2/s at 35°C and 1.10 × 10−8 m2/s at 55°C.