Extraction of cocoa butter by supercritical carbon dioxide: optimization of operating conditions and effect of particle size.

The optimum operating conditions for the extraction of cocoa butter from cocoa liquor using supercritical carbon dioxide and the effect of sample particle size on cocoa butter extraction under optimized operating conditions were investigated. The optimization was conducted at 10–45 MPa and 35–75C, with extraction times of 1–12 h by response surface methodology. The effect of particle size was studied using cocoa liquor, ground cocoa nibs and crushed cocoa nibs with particle sizes of approximately 74 µm, 0.85–1 mm and 4–6 mm, respectively. The yield was analyzed for total fat content by gravimetric method and triacylglycerol (TAG) profile by high-performance liquid chromatography. The results showed higher yield of cocoa butter with higher values of pressure, temperature and extraction time. The optimum conditions for cocoa butter extraction were 45 MPa, 75C and 12 h. The smaller particle size produced a higher yield of cocoa butter. 1,3-Dipalmitoyl-2-oleoyl-glycerol (POP), 1-palmitoyl-2-oleoyl-3-stearoyl-glycerol (POS) and 1,3-distearoyl-2-oleoyl-glycerol (SOS) were the major TAGs present in the extracted cocoa butter, with POS being the highest (>30%) for all treatments studied

Phosphatidylcholine solubility in supercritical carbon dioxide: experimental data, thermodynamic modeling, and application in bioactive-encapsulated liposome synthesis

The solubility of phosphatidylcholine (PC) in supercritical-CO2 (SC-CO2) was measured experimentally using a dynamic system for the pressure and temperature range of 12.4–17.2 MPa and 313−353 K, respectively. The data were used to model the solubility using three cubic equations of state (EOS) combined with the conventional one parameter mixing rule: Soave–Redlich–Kwong (SRK); Peng–Robinson (PR); and van der Waals EOS, modified with Soave's approach (MvdW). MvdW EOS demonstrated the best fit with experimental data. The optimal solubility condition was used to synthesize liposomes by using a venturi-based rapid expansion of supercritical solutions technique (Vent-RESS). Three model bioactives were simultaneously co-encapsulated into synthesized liposomes: one lipophilic bioactive, vitamin E; and two hydrophilic bioactives, vitamin-C and iron sulfate. Vitamin E, vitamin C, and iron sulfate demonstrated an average encapsulation efficiency of 95.1, 77.8, and 63.3 %, respectively158sem informaçãosem informaçã

Kinetics of methane hydrate decomposition

The kinetics of methane hydrate decomposition was studied using a semibatch stirred-tank reactor. The decomposition was accomplished by reducing the pressure on a hydrate slurry in water to a value below the three-phase equilibrium pressure at the reactor temperature. The data were obtained at temperatures from 274 to 283 K and pressures from 0.17 to 6.97 MPa. The stirring rates were high enough to eliminate mass-transfer effects. Analysis of the data indicated that the decomposition rate was proportional to the particle surface area and to the difference in the fugacity of methane at the equilibrium pressure and the decomposition pressure. The proportionality constant showed an Arrhenius temperature dependence. An estimate of the hydrate particle diameters in the experiments permitted the development of an intrinsic model for the kinetics of hydrate decomposition