Optimization of supercritical fluid extraction of phenolic-compounds from palm kernel cake and its antioxidant activity

Abstract. Palm Kernel Cake (PKC), a byproduct of the palm oil industry, is rich in phytochemical compounds, including phenolic acids, and has various potential applications. This study aimed to analyse the Total Phenolic Content (TPC) and Antioxidant Activity (AOA) of PKC extracts using Supercritical Fluid Extraction (SFE). The phenolic compounds extracted from the PKC were optimised using the Response Surface Methodology (RSM) approach. Three parameters, pressure (150-300bar), temperature (40-80°C), and extraction time (20-60 minutes), were varied to optimise the TPC extraction. The results, displayed through response surface plots, showed that the TPC ranged from 1.99 to 3.05 mg of Gallic Acid Equivalent (GAE)/g bio-oil, with an R2 value of 0.9890, indicating high accuracy. The optimised conditions of a temperature of 80°C, pressure of 300bar, and reaction time of 42 minutes led to a TPC of 3.035mg of GAE per g of bio-oil. Additionally, the highest AOA value, 68.11g of Ascorbic Acid Equivalent (AAE)/mL solvent, was obtained at a condition pressure of 300bar, temperature of 60°C and extraction time of 40 minutes. The study highlights the potential of SFE for extracting valuable compounds from PKC, which could find applications in industries such as cosmetics and medicine due to their antioxidant, anti-aging, anti-inflammatory, and antiproliferative properties.