Phase Equilibrium Study Of Β-Carotene, Tocopherols And Triacylglycerols In Supercritical Fluid Extraction Process From Crude Palm Oil Using Carbon Dioxide As A Solvent

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Date
2010-03
Authors
Davarnejad, Reza
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Publisher
Universiti Sains Malaysia
Abstract
Phase equilibrium of the substances from a multi-component system such as crude palm oil in sub and supercritical carbon dioxide solvent has become increasingly important particularly in unit operation processes. In this study, two rigs have been fabricated and calibrated to study the supercritical fluid extraction of β-carotene from crude palm oil and also to evaluate the phase equilibrium of the supercritical extraction of β-carotene, triacylglycerols (TAGs) and tocopherols from crude palm oil using carbon dioxide as a solvent. For the phase equilibrium study, the mutual solubility of β-carotene, TAGs and tocopherols from crude palm oil using carbon dioxide as a solvent were in the temperature range of 80 ºC to 120 ºC. Each sample from the phase equilibrium unit contained two parts. The liquid part was analyzed by chromatography and the vapor part was conducted to an expansion vessel to measure pressure increment during expansion process. In order to analyze the liquid samples, a spectrophotometer, a gas chromatography (GC) and a high performance liquid chromatography (HPLC) were employed to determine the compositions of β-carotene, four tocopherols components (α-, β-, γ- and δ-tocopherol) and three triacylglycerols components [1, 3-dipalmitoyl-2-oleoyl-glycerol (POP), 1, 2-dioleoyl-3-palmitoyl-rac-glycerol (POO) and 1, 2-dioleoyl-3-stearoyl-rac-glycerol (SOO)] in crude palm oil, respectively. Two phase equilibrium data was calculated using liquid phase composition and pressure increment during expansion process. Results showed that the maximum solubility of three groups of components around 2.27 % at temperature of 120 ºC and at pressure 5.44 MPa. Although the composition of the components from crude palm oil has slightly changed but, from scale up point of view the reported data as mentioned above would be applicable. This could be due to the pressure increment that considerable influenced on the calculated data. On the other hand, high solubility of triacylglycerols in carbon dioxide may be assisted as a co-solvent in high solubility of other substances. The results obtained from the experiment were also compared with the theoretical data obtained from the mutual solubility calculations associated with the Gibbs function which were applied as the theoretical model in this research. The mutual solubility calculations associated with the Gibbs function was applied in each phase by applying the activity coefficient expressions. This model approach has been found to be encouraging for the prediction of vapor phase while some differences between the experimental and theoretical data for liquid phase were observed. The reasons of this were partly due to the uncertainty and interaction parameters calculated from another set of equilibrium data obtained from the literature. It also showed that the interaction parameters were dependent on pressure. For the rate test study, a Design of Expert (DOE) software version 6.0.6 was used to optimize the operating conditions. Twenty runs were carried out at various range of pressure 7.5 MPa to 17.5 MPa with temperature between 80 ºC to 120 ºC and extraction time 1 hour to 5 hour, respectively. Crude palm oil as a liquid sample was extracted from the rate test supercritical extraction apparatus at various conditions and was analyzed via spectrophotometer in order to study the yield of β-carotene extraction.
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Keywords
The supercritical fluid extraction of β-carotene from crude palm oil , to evaluate the phase equilibrium of the supercritical extraction of β-carotene
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