Designed polar cosolvent-modified Supercritical CO2 removing caffeine from and retaining catechins in green tea powder using response surface methodology

This study examines cosolvent-modified supercritical carbon dioxide (SC-CO2) to remove caffeine from and to retain catechins in green tea powder. The response surface method was adopted to determine the optimal operation conditions in terms of the extraction efficiencies and concentration factors of caffeine and catechins during the extractions. When SC-CO2 was used at 333 K and 300 bar, 91.5% of the caffeine was removed and 80.8% of catechins were retained in the tea: 3600 g of carbon dioxide was used in the extraction of 4 g of tea soaked with 1 g of water. Under the same extraction conditions, 10 g of water was added to < 800 g of carbon dioxide in an extraction that completely removed caffeine (that is, the caffeine extraction efficiency was 100%). The optimal result as predicted by three-factor response surface methodology and supported by experimental data was that in 1.5 h of extraction, 640 g of carbon dioxide at 323 K and 275 bar with the addition of 6 g of water extracted 71.9% of the caffeine while leaving 67.8% of the catechins in 8 g of tea. Experimental data indicated that supercritical carbon dioxide decaffeination increased the concentrations of caffeine in the SC-CO2 extracts at 353 K

Identification and evaluation of antioxidants defatted Camellia oleifera seeds by isopropanol salting-out pretreatment

Seven flavonoid glycosides (1-7) and one theasaponin (8) were isolated from the defatted Camellia oleifera seeds using the isopropanol salting-out pretreatment (ISP) technique, followed by column chromatography. Among them, compounds 5, 7, and 8 are new compounds. The comparison of oxygen radical absorbance capacity (ORAC) of crude extracts extracted by the n-butanol partition (BP) with those extracted by the ISP showed that the latter method yields eight times greater scavenging capacities than that of the former approach. Besides, ISP exhibited almost twice the extraction efficiency than that of BP. ORAC and Trolox equivalent antioxidant capacity (TEAC) analysis revealed that the most potent antioxidants are compounds 1 and 2, which exhibited 1.78 and 1.41 times higher antioxidant activity than that of Trolox, respectively. These results indicated that the ISP approach improves the extraction efficiency in the isolation of potent antioxidants, making the defatted C. oleifera seeds valuable in the food additive industry. (C) 2010 Elsevier Ltd. All rights reserved

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

This study examines the supercritical carbon dioxide (SC-CO2) 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-CO2 extracts were determined. With top-flow type SC-CO2 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 CO2 was consumed during the extraction of 35 g rice bran powder. The concentration factors of oryzanols and triglycerides in SC-CO2-extracted oil were higher than in the Soxhlet n-hexane extracted oil. SC-CO2 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-CO2 extracted oil

Precipitation of sub-micron particles of 3,5-diprenyl-4-hydroxycinnamic acid in Brazilian propolis from supercritical carbon dioxide anti-solvent solutions

This study elucidates supercritical carbon dioxide (SC-CO(2)) anti-solvent precipitation of 3, 5-diprenyl-4-hydroxycinnamic acid (DHCA) from the ethyl acetate solution of ultra-green Brazilian propolis. The SC-CO(2) anti-solvent process at 20 MPa and 328 K generated the precipitates containing DHCA (306 mg/g) more than that of the Soxhlet ethyl acetate extract (204 mg/g). A two factorial central composite response surface methodology was adopted to examine the effects of CO(2) flow rate and CO(2) expansion volume on mean particle size of the precipitate. Analysis of the DHCA recovered indicated that both factors are significant. The mean particle size fell as the CO(2) flow rate or the CO(2) volume increased. Finally, the dose-dependent concentrations from 25 to 400 mu g/mL demonstrated that aqueous samples of the precipitated SC-CO(2) particulates effectively inhibited the growth of human colon (colo-205) cancer cells. (C) 2009 Elsevier B.V. All rights reserved

Continuous hot pressurized solvent extraction of 1,1-diphenyl-2-picrylhydrazyl free radical scavenging compounds from Taiwan yams (Dioscorea alata)

This study investigates a semicontinuous hot pressurized fluid extraction process and the scavenging activity on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical of the extract from Taiwan yams (Dioscorea alata). Liquid-liquid extractions were preliminarily employed to generate six fractions, initially extracted by ethanol. Then, the aqueous solution of dried crude ethanol extract was sequentially fractionated by hexane, chloroform, ethyl acetate, and n-butanol. The EC50 value was defined as the UV absorption of DPPH concentrations sufficiently decreased to 50% of the original value. It was found that all peel portions have a better effect on scavenging of the DPPH free radical than meat portions, especially for the ethyl acetate partition of the peel portion of Tainung #2 yam. Its EC50 value (14.5 mug mL(-1)) was even lower than that of ascorbic acid (21.4 mug mL(-1)). Furthermore, semicontinuous hot pressurized ethanol was superior to hot pressurized water in extracting the compound scavenging the DPPH radical from the Purpurea-Roxb peel. The recovery of four unknown compounds corresponded to the scavenging ratio of DPPH free radical in the hot pressurized ethanol extract. Finally, three-level and four-factor experimental design revealed that ethanol ratio and temperature were the most effective factors in order. Conditions of 80% of aqueous ethanol, 20.0 kg/kg solid ratio, 180 psig (1.342 MPa), and 100degreesC were preferred to extract those antioxidants from the yam peel

Application of continuous supercritical anti-solvents for rapid recrystallization and purification of zeaxanthin dipalmitates from de-glycosides of Lycium barbarum fruits

This study employed column elution fractionation coupled with supercritical anti-solvent recrystallization to isolate the purest zeaxanthin dipalmitates (ZP), one of the eye-protecting compounds in the Lycium barbarum fruits. The amount of ZP increased to 983 mg/gin liquid anti-solvent precipitates with 29.1% recovery and increased to 929 mg/gin supercritical anti-solvent precipitates with 59.6% recovery, respectively from the ultrasonic acetone extract. Experimental data showed that supercritical anti-solvent recrystallization is feasible in producing platelet type precipitates within a few minutes. These ZP compounds exhibit anti-oxidative abilities by proliferating human adult retinal pigment epithelial cells (from 22% to 31%); though it was a meager increase when compared to those of algal 95% zeaxanthin (from 43% to 94%). (C) 2011 Elsevier B.V. All rights reserved

Extraction of antioxidative compounds from wine lees using supercritical fluids and associated anti-tyrosinase activity

This study examines a co-solvent-modified supercritical carbon dioxide (m-SC-CO(2)) extraction of polyphenols from rice wine lees. Chemical antioxidative activity, inhibitive melanoma tyrosinase and melanin that had been treated by the extracts were studied. Experimental results indicate that the Soxhlet 95% ethanol extract was effective in alpha,alpha-diphenyl-beta-picryl-hydrazyl (DPPH) radical scavenging (86%), ferrous ion chelating (91%), reducing ability (1.877 optical density value; OD) and tyrosinase inhibition (57%). Among the m-SC-CO(2) extracts, the best antioxidative capacity was DPPH radical scavenging (31%), ferrous ion chelating (74%) and reducing ability (0.2373 CD). The amount of polyphenols in the extracts increased with the addition of ethanol in the m-SC-CO(2) extraction, enhancing the antioxidative activity and tyrosinase inhibition in cells tests. The tyrosinase inhibition in an agar-plate that was treated by mSC-CO(2) extract is more effective than that of Soxhlet 95% ethanol extract, indicating that the polyphenols contents in the extracts are important in the suppression of tyrosinase and melanin. (C) 2009 Elsevier B.V. All rights reserved

Demonstration of continuous supercritical carbon dioxide anti-solvent purification and classification of nano/micro-sized precipitates of algal zeaxanthin from Nannochloropsis oculata

This study examined time dependent continuous supercritical anti-solvent (SAS) recrystallization applied for purifying and generating zeaxanthin rich particulates from micro-algal Nannochloropsis oculata. Feed solutions varied from 0.4 to 1.2 mg/ml subjected into a 250 ml SAS crystallizer to yield a few classifications of nano- or micro-sized purified precipitates corresponding to different recrystallization time zones. The effect of operational conditions on amount, recovery of the zeaxanthin and mean size, morphology of the precipitates was obtained from experimentally designed SAS process. The mean size of particles falls within several hundreds of nanometers and the content of zeaxanthin in the particulates range from 65 to 71%, which relies highly upon the recrystallization time. This work demonstrated an environmental benign process in producing nano- or micro-sized particles containing rich-zeaxanthin from algal solution by using supercritical anti-solvent within minutes. (C) 2010 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved