Influence of particle size in supercritical carbon dioxide extraction of roselle (Hibiscus sabdariffa) on bioactive compound recovery, extraction rate, diffusivity, and solubility

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 & DEG;C), and particle size (250 & mu;m < dp < 355 & mu;m, 355 & mu;m < dp < 425 & mu;m and 425 & mu;m < dp < 500 & mu;m) 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 & DEG;C and 250 & mu;m < dp < 355 & mu;m, 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/s(2), 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 & mu;m < dp < 355 & mu;m. 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.

Automated summary

The aim of this study was to determine the optimal particle size for the efficient recovery of total phenolic compounds (TPC), total anthocyanin compounds (TAC), and total flavonoid compounds (TFC) from roselle using supercritical carbon dioxide (ScCO2). The extraction rate, diffusivity, and solubility of ScCO2 were also investigated. The results showed that the smallest particle size of roselle (250μm < dp < 355μm) provided the highest recovery and solubility of bioactive compounds. Additionally, decreasing the particle size increased the diffusivity and extraction efficiency of ScCO2. Hence, a smaller particle size is recommended for roselle extraction using ScCO2 based on both experimental and modeling data.