Parameter Effects and Optimisation in Supercritical Fluid Extraction of Phenolic Compounds from Labisia pumila

Labisia pumila, locally referred to as kacip fatimah, is one of the important herbs utilised in traditional medicine. Nonetheless, to the best of the researchers’ knowledge, the optimum application of Supercritical Fluid Extraction (SFE) has not been reported for Labisia pumila (L. pumila) extraction and the understanding of this study may offer preliminary insight into the preparation of standardised extracts of L. pumila enriched with natural antioxidants prior to commercialisation at the industrial level. Response surface methodology (RSM) was used to optimise supercritical carbon dioxide extraction (SC-CO2) of functional phenolic compounds from L. pumila leaves. The factors studied were pressure, temperature, percentage of ethanol in co-solvent, and co-solvent concentration. The results demonstrated that the percentage of ethanol in co-solvent, temperature, and co-solvent concentration in the supercritical mixture had significant effects on the extraction of L. pumila. Based on the RSM results, the optimal SC-CO2 extraction conditions were at 283 bar, 32 °C, 78% (v/v) of ethanol-water in co-solvent, and 16% (v/v) of co-solvent concentration, which allowed the recovery of 14.051 ± 0.76% (g/g) of extraction yield, 1.2650 ± 0.10% (g/g) of gallic acid, 0.441 ± 0.29% (g/g) of methyl gallate, and 1.382 ± 0.37% (g/g) of caffeic acid. The experimental values were in agreement with the one predicted by RSM models, confirming the suitability of the model for optimisation of the extraction conditions.