Extraction of Phytochemical Compounds from Eucheuma cottonii and Gracilaria sp using Supercritical CO2 Followed by Subcritical Water

Abstract

Extraction of phytochemical compounds (such as β-carotene, linoleic acids, carrageenan, and polyphenols) from algae Eucheuma cottonii and Gracilaria sp with supercritical CO2 followed by subcritical water has been investigated. Supercritical CO2 extraction was carried out at pressure of 25 MPa, temperature of 60°C, CO2 flowrate of 15 ml/min, and ethanol flowrate of 0.25 ml/min. To determine the content of carotenoids and linoleic acids, the extracted compounds were analyzed using a spectrophotometer UV-Vis. The residue of algae starting material was subsequently extracted by subcritical water at pressures of 3, 5, and 7 MPa, and temperatures of 120, 140, 160, and 180 °C. Carrageenan extracted by subcritical water was analyzed using Fourier Transform Infra Red (FTIR), while the total phenolic compound was analyzed with UV-vis spectrophotometer. Moreover, the antioxidant efficiency of extract was also examined by DPPH assay method. Based on the analytical result, β-carotene and linoleic acid content in Eucheuma cottonii were 209.91 and 321.025 μg/g sample, respectively. While β-carotene and linoleic acid content in Gracilaria sp were 219.99 and 286.52 μg/g sample, respectively. The optimum condition of subcritical water extraction was at 180°C and 7 MPa. At this condition, the highest TPC content in the extract from Eucheuma cottonii and Gracilaria sp were 18.51 mg GAE/g sample and 22.47 mg GAE/g sample, respectively; while the highest yield of carrageenan extracted from Eucheuma cottonii and Gracilaria sp were 61.33 and 65.54 g/100 g dried algae, respectively. At the same condition, the antioxidant efficiency was 0.513 min-1 for Eucheuma cottonii and 0,277 min-1 for Gracilaria sp. Based on the results the extraction method effectively separated non-polar and polar compounds, then increased the antioxidant efficiency of extract.