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The purpose of this work was to establish the best particle size for recovering high yields of total phenolic compounds (TPC), total anthocyanin compounds(TAC) and total flavonoid compounds (TFC) from roselle (Hibiscus sabdariffa) by applying supercritical carbon dioxide (ScCO2). The extraction rate, diffusivity and solubility of yield in ScCO2 were also studied and calculated utilizing models. Pressure (10 and 30 MPa), temperature (40 and 60 °C), and particle size (250 µm < dp < 355 µm, 355 µm < dp < 425 µm and 425 µm < dp < 500 µm) were employed as variables in this experiment. The greatest recovery was 11.96% yield, 7.16 mg/100 g TAC, 42.93 mg/100 g TPC and 239.36 mg/100 g TFC under the conditions of 30 MPA, 40 °C and 250 µm < dp < 355 µm, respectively. The extraction rate of supercritical carbon dioxide in roselle extraction ranged from 5.19 E−03 to 1.35 E−03 mg/s fitted using the Esquivel model. The diffusivity coefficient of ScCO2 ranged from 2.17E−12 to 3.72E−11 mg/s2, as fitted by a single sphere model. The greatest solubility of global yield, TAC, TPC and TFC in ScCO2 was 1.50 g/L, 0.3 mg/L, 1.69 mg/L and 9.97 mg/L, respectively, with a particle size of 250 µm < dp < 355 µm. The smaller particle size of roselle provides the maximum bioactive compound recovery and solubility. Furthermore, the diffusivity and extraction of ScCO2 are increased by decreasing the particle size. Therefore, a smaller particle size is appropriate for roselle extraction by ScCO2 based on the experimental and modelling data. [ABSTRACT FROM AUTHOR]

A scientific investigation on the optimization and solubilization of anthocyanin from roselle by subcritical ethanol (SE) has not yet been conducted. Consequently, the purpose of this work is to evaluate the parameter influences on anthocyanin recovery by SE, followed by the identification of the solubilization behavior by semi-empirical modelling. The best conditions were 8.74 MPa, 383.51 K and 5.21 mL/min with responses of global yield of 0.765 g/g, anthocyanin of 921.43 mg/100 g, TPC of 40.57 mg/100 g and TFC of 559.14 µg/g. High pressure and temperature conditions are conducive to global yield, anthocyanin, flavonoid and phenolic recovery. The Del Valle Aguilera model fits the solubility of global yield and anthocyanin in SE effectively instead of Chrastil model since it has the lower average absolute relative deviation (AARD), which is 11.54 % and 7.15 %, respectively. The most influenced parameters were found to be the temperature, which gave a significant impact in enhancing the solubization power of global yield and anthocyanin. [ABSTRACT FROM AUTHOR]

This study aims to develop a new semi-empirical model to fit solute solubility in a mixture of solvents, viz. supercritical carbon dioxide, ethanol, and water, as well as to evaluate the effects of competing solvents on solubility. Therefore, the model was assessed by fitting the published solubility data and comparing it with the established semi-empirical models. The findings revealed that the new model gave the highest coefficient of determination, R2 of 0.96 and had the lowest AARD (i.e., 3.88%), compared to other models. To conclude, the new model is feasible in determining three solvents' solvation effects in one system. [ABSTRACT FROM AUTHOR]

Rosmarinic acid (RA) is present in a broad variety of plants, including those in the Lamiaceae family, and has a wide range of pharmacological effects, particularly antioxidant activity. To extract RA from Orthosiphon stamineus (OS) leaves, a Lamiaceae plant, a suitable extraction process is necessary. The present study used a green extraction method of supercritical carbon dioxide (SCCO2) extraction with the addition of ethanol as a modifier to objectively measure and correlate the solubility of RA from OS leaves. The solubility of RA in SCCO2 was determined using a dynamic extraction approach, and the solubility data were correlated using three density-based semi-empirical models developed by Chrastil, del Valle-Aguilera, and Gonzalez. Temperatures of 40, 60, and 80 °C and pressures of 10, 20, and 30 MPa were used in the experiments. The maximum RA solubility was found at 80 °C and 10 MPa with 2.004 mg of rosmarinic acid/L solvent. The RA solubility data correlated strongly with the three semi-empirical models with less than 10% AARD. Furthermore, the fastest RA extraction rate of 0.0061 mg/g min−1 was recorded at 80 °C and 10 MPa, and the correlation using the Patricelli model was in strong agreement with experimental results with less than 15% AARD. [ABSTRACT FROM AUTHOR]

The purpose of this work was to determine the optimal conditions for recovering high yields of total phenolic compounds (TPC), total flavonoid compounds (TFC), and antioxidant activity (AA) from roselle (Hibiscus sabdariffa) by employing supercritical carbon dioxide (ScCO2). The solubility of yield, phenolic, and flavonoid in ScCO2 was estimated using solubility models. Pressure (10 to 20 MPa), temperature (40 to 60°C), and flow rate (3 to 5 ml/min) were used as factors in this investigation. According to the response surface methodology (RSM), the optimal conditions were 20 MPa, 40°C, and 4.875 ml/min, yielding 14.11%, 935.48 mgGAE/L TPC, 812.16 mgQUE/L TFC, and 98.59% antioxidant activity, respectively. With 5.29%, 1.28%, and 1.34% of average absolute relative deviation (AARD), the Putra model provided the best connection to the yield extract, phenolic, and flavonoid solubility. The use of RSM and modeling was effective in attaining a high production and concentration of phenolic compounds. Practical applications: Roselle (Hibiscus sabdariffa) comprises several beneficial components, including phenolic, flavonoid, and antioxidant substances. It is used to treat pyrexia, liver damage, hypertension, and leukemia, among other conditions. Toxic and conventional solvents, on the other hand, have often been utilized to recover these valuable compounds. To alleviate these disadvantages, the important chemicals in roselle are extracted using supercritical carbon dioxide (ScCO2). The solubility behavior of oil yield, phenolic, and flavonoid compounds was determined in this work using a semi‐empirical model. The data indicate that an endothermic process occurred to enhance the solubility of yield extract and the exothermic process is suitable for the phenolic and flavonoid recovery. [ABSTRACT FROM AUTHOR]

An accurate and suitable semi-empirical model is crucial to determine the solubility of plant extracts in supercritical carbon dioxide (SC-CO2) assisted by ethanol as a co-solvent. In this paper, a new solubility model was proposed to correlate the plant solubility to SC-CO2 and ethanol. The accuracy and capability of the new model were evaluated by fitting it with published solubility datasets. The overall percentage of average absolute relative deviation was 12.13%, and the average coefficient of determination (R2) was 0.89. Comparisons between the results of the new model and the published models showed an excellent capability and accuracy in fitting solute solubility in SC-CO2 in the presence of ethanol as a co-solvent. [ABSTRACT FROM AUTHOR]