Optimization of turmeric oil extraction in an annular supercritical fluid extractor by comparing BBD-RSM and FCCD-RSM approaches

Abstract

Comparison between the performances of two important statistical response surface modelling methods of Face Centered-Central Composite Designs (FCCD-RSM) and Box-Behnken Designs (BBD-RSM) were performed to find the optimum operating conditions of extraction pressure, temperature and particle size that can maximize the yield obtained from grated turmeric rhizomes when extracted under the influence of a specially designed annular extractor bed using supercritical carbon dioxide extraction (SCO2E). The effects of operating pressure, temperature and particle size were investigated at the extraction pressure of 21.6 MPa, 24.55 MPa or 27.5 MPa; the extraction temperature of 40°C, 50°C or 60°C; and the particle sizes of 0.3 mm, 0.6 mm or 0.9 mm. Yield of turmeric oil was varied from 1.84 wt% – 4.45 wt% for different combinations of operating parameters used in extraction following FCCD-RSM and BBD-RSM. Both the methods were identified as efficient to build the experimental design and optimize the process by fitting the experimental data in quadratic models within the design range. FCCD-RSM based optimization furnishes a set of optimal conditions of 26.859MPa extraction pressure, 59.886°C extraction temperature and 0.301 mm particle size with a slightly better yield (4.452%) as compared with BBD-RSM based optimization (27.325MPa extraction pressure, 58.417°C extraction temperature and 0.31 mm particle size with a yield of 4. 403%). Considering the time of performing all experiments, labour, and cost involved in three factors-three levels of optimization, BBD-RSM is proposed as a well-accepted alternate method of experimental design in the RSM study of SCO2E of turmeric oil under the influence of annular extractor along with the more acceptable FCCD-RSM.