Chao-Rui Chen

Designing supercritical carbon dioxide extraction of rice bran oil that contain oryzanols using response surface methodology

This study examines the supercritical carbon dioxide (SC-CO(2)) extraction of oryzanols contained rice bran oil from powdered rice bran. The extraction efficiencies and concentration factors of oryzanols, free fatty acids and triglycerides in the SC-CO(2) extracts were determined. With top-flow type SC-CO(2) extraction the total oil yield was 18.1% and the extraction efficiencies of oryzanols and triglycerides were 88.5 and 91.3% respectively, when 2750 g CO(2 )was consumed during the extraction of 35 g rice bran powder. The concentration factors of oryzanols and triglycerides in SC-CO(2)-extracted oil were higher than in the Soxhlet n-hexane extracted oil. SC-CO(2) extractions indicated that pressure can be used more effectively than temperature to enhance the extraction efficiency and concentration factor of oryzanols. A two-factor central composite scheme of response surface methodology was employed to determine the optimal pressure (300 bar) and temperature (313 K) for increasing the concentration of oryzanols in the SC-CO(2) extracted oil.

Preparation of highly pure zeaxanthin particles from sea water-cultivated microalgae using supercritical anti-solvent recrystallization

Xanthophylls, including zeaxanthin, are considered dietary supplements with a potentially positive impact on age-related macular degeneration. Using pilot-scale column fractionation coupled with supercritical anti-solvent (SAS) recrystallization, highly pure zeaxanthin particulates were prepared from ultrasonic extracts of the microalgae, Nannochloropsis oculata, grown in sea water. Column partition chromatography increased the concentration of zeaxanthin from 36.2 mg/g of the ultrasonic extracts to 425.6 mg/g of the collected column fractions. A response surface methodology was systematically designed for the SAS process by changing feed concentration, CO(2) flow rate and anti-solvent pressure. Zeaxanthin-rich particles with a purity of 84.2% and a recovery of 85.3% were produced using supercritical anti-solvent recrystallization from the column eluate at a feed concentration of 1.5 mg/mL, CO(2) flow rate of 48.6 g/min and pressure of 135 bar.

Application of Supercritical Fluids for Biodiesel Production

This chapter elucidates supercritical carbon dioxide (SC-CO2) extraction of triglycerides from powdered Jatropha curcas kernels and seeds, followed by a series of subcritical hydrolysis and supercritical methylation of the extracted SC-CO2 oil to obtain a 98.5% purity level of biodiesel. Effects of the reaction temperature, the reaction time, and the solvent-to-solid ratio on free fatty acid (FFA) in the hydrolyzed oil and fatty acid esters in the methylated oil via two experimental designs were also examined. Supercritical methylation of the hydrolyzed oil following subcritical hydrolysis of the SC-CO2 extract yielded a methylation reaction conversion of 99%, and activation energies of hydrolysis and transesterified reactions were found, respectively. This study demonstrates that supercritical methylation preceded by subcritical hydrolysis of the SC-CO2-extracted oil is a feasible two-step process in producing biodiesel from powdered Jatropha kernels better than that from Jatropha seeds. The economical estimation of the process was also examined.

Green Fluids Extraction and Purification of Bioactive Compounds from Natural Materials

This article introduces green solvent extraction and purification of few marker compounds from propolis and rice bran using supercritical carbon dioxide (SC-CO2). The purity (41.2 wt%) of 3,5-diprenyl-4-hydroxycinnamic acid (DHCA) was recovered from propolis using SC-CO2 at 207 bar and 323 K with ethyl acetate (6 wt%) addition. The addition of a normal-phase column adsorption approach was directly employed to obtain purified product containing 95 DHCA by weight. SC-CO2 antisolvent micronization at 200 bar and 328 K generated the submicron particulates containing DHCA (35.2 wt%) from the solution of Brazilian propolis extracts, and the enhancement factor for DHCA concentration reached to 1.61. The DHCA effectively inhibited the growth of human leukemia, colon as well as breast cancer cells, and the human serum low-density lipid oxidation in bioassay. This work also elucidates SC-CO2 extraction of rice bran oil at 300 bar and 313 K from 1.03-kg powdered rice bran. The total yield of oil was 15.7% with a free fatty acid (FFA) content of 3.75%, obtained from 20.5 kg of carbon dioxide. An oil retention efficiency of 82.2% and an FFA removal efficiency of 97.8% were achieved by using SC-CO2 deacidification at 250 bar and 353 K with 2,700 g of carbon dioxide consumed. Besides, the two purest γ-oryzanols (>98 wt%) were isolated by preparative reverse-phase high-performance liquid chromatography (HPLC). Furthermore, the central composite response surface methodology (RSM) was applied to predict the optimal operating conditions and to examine the significance of experimental parameters by a statistic analysis.