Kinetic studies on Zingiber officinale

The present investigation deals with the isolation, purification and characterization of gingerol, the major pungent constituent of ginger (Zingiber officinale) and its kinetic of extraction using a number of organic solvents. The characterization was carried out through GC and GC-MS. Gingerol has been assayed in the plant material during extraction with various solvents by a HPLC method. In order to develop a relationship between solvent characteristics such as viscosity and dielectric constant and the rates of extraction, the kinetics of extraction of gingerol has been studied by using twelve different solvents in order to evaluate the solvent efficacy in the extraction processes. It has been observed that both solvent viscosity (1/v) and dielectric constant (epsilon) show a linear relationship with the rates of extraction (k). An increase in solvent viscosity leads to a decrease in the rates of extraction, similarly an increase in dielectric constant also leads to a decrease in the rates of extraction. This appears to be largely due to an unionizable character of gingerol which does not interact with polar solvents. Thus solvent viscosity and dielectric constant both play an important role in the choice of solvents for the extraction of gingerol. Solvents with relatively low viscosity and dielectric constant are more suitable for the extraction of gingerol from plant material.