Modelling and optimisation of Eurycoma longifolia extraction utilising a recirculating flow extractor

Abstract

In this study, Tongkat Ali was extracted with a newly designed recirculating flow extractor with temperature and flow rate as the operating parameters. The optimum duration and ratio for extraction were found to be 90 min and 40:1 w/w, respectively. The determination of optimal operating parameter value for this extractor was based on maximum percentage extract yield and solid diffusivity, Ds,. From the experiments, it was found that the temperature and flow rate that produce the highest yield and solid diffusivity value were at 90°C and 400 rpm (22.47 mL sec-1), respectively. The optimal operating parameter values were used to compare the recirculating flow extractor performance with a batch extraction at 90°C. The comparison showed that the batch extraction was able to extract more rapidly than the recirculating flow extractor. The solid diffusivity, Ds, value for the batch extraction was found to be is 3.12 × 10-11 m2 sec-1 while the recirculating flow extractor had a solid diffusivity, Ds, value of 2.98×10-11 m2 sec-1 which indicated the difference in extraction rate. However, by utilizing the recirculating flow extractor, a higher final yield than batch extraction was produced which is 7.70% (w/w) for the recirculating flow extractor and 6.67% (w/w) for the batch extraction. This is possibly caused by the higher rates of solvent losses through evaporation for batch extraction.