Diffusion Properties of Garcinia Fruit Acids (Garcinia atroviridis)

The diffusion properties of garcinia fruit acids (Garcinia atroviridis) were investigated in a batch reactor. The influences of two variables were studied: material thickness and extraction temperature. Stirring was continuous to assure turbulent flow inside the vessel. Garcinia fruits were sliced into infinite slabs of two different thicknesses, 2.5 and 4.0 mm. Each group of a given thickness was then separated into three sub-groups. Each sub-group was then subjected to individual extraction temperatures of 50 °C, 60 °C and 70 °C. Distilled water was used as the extraction solvent. The experiment was carried out in well-agitated vessel with a ratio of water to fruit material of 30:1 (w/w). Each experiment took an operating extraction time of 3 h; unless it was under equilibrium conditions, in which case it was left for a further 24 h. Solid samples were taken at different periods and the amount of total acids determined. The total acid concentration was then calculated. Diffusion properties like solute diffusivities, times of cell plasmolysis, equilibrium distribution coefficients and volumetric mass transfer coefficients were determined to be in the range of 7.95×10-10 - 12.14×10-10 m2/s for diffusivities, 346.3 - 1158.4 s for times of cell plasmolysis, 1.06 - 1.07 for equilibrium distribution coefficients, and 3.85×10-4 - 9.40×10-4 s-1 for volumetric mass transfer coefficients. These values are thus available for simulation purposes and optimization of the processing operation.