Fractionation of fish oil with supercritical carbon dioxide

In order to verify the possibility of using supercritical CO₂ (SC-CO₂) to concentrate polyunsaturated ω−3 fatty acids in the form of natural fish oil, experimental phase equilibrium data were measured for a CO₂ – fish oil system. Phase equilibrium was measured at temperatures from 301 to 323 K and pressures from 7.8 to 29.4 MPa, using the dynamic method. The oil solubility and fatty acid composition of the extracts were measured and these data used to verify CO₂ selectivity. The best operational conditions to fractionate the oil were 7.8 MPa and 301.15 K, although in all the conditions analyzed, eicosapentaenoic acid (EPA) could not be fractionalized. The equilibrium for a mixture of 50% fish oil and 50% babassu (Attalea funifera) fat was measured in order to understand how the fatty acid composition influenced the fractionation. It was observed that the solubility of the mixture was an average of the individual solubility values, and the composition of the extracts could be calculated from the individual solubility of each component.     

大蒜超临界CO2萃取物成分分析

对大蒜超临界CO2萃取物进行了GC-MS分析，借助NTST98.L数据库的质谱图数据，参考文献和人工解析对其中的20多种组分进行，定性鉴定，并利用峰面积归一化法进行了初步定量。大蒜风味物的GC-MS分析表明：大蒜超临界CO2萃取物中含有许多水蒸汽蒸馏蒜油中没有检测到的风味成分，其中最显蔷的是蒜素色谱分析中脱水衍生的3-乙烯基-l，2-二硫杂-4-环已烯(3．96％)及3-乙烯基-1．2-二硫杂-5-环己烯(17．88％)，此外还含有少量的亚油酸及油酸。     

Impact of ethanol addition on the solubility of various soybean isoflavones in supercritical carbon dioxide and the effect of glycoside chain in isoflavones

Solubilities of glycoside isoflavones (daidzin, genistin and glycitin) and their aglycons (daidzein, genistein and glycitein) in supercritical carbon dioxide (SCCO₂) were measured. In the SCCO₂-only system, the solubility of glycoside isoflavones was very low. Adding over 0.1 molar fraction of ethanol to SCCO₂ increased the solubility of glycoside isoflavones. The solubility was almost proportional to the third power of the molar fraction of ethanol. Adding ethanol significantly affected the solubility of glycoside isoflavones. In particular, the solubility of daidzin was remarkably increased by ethanol addition. The solubility of six tested isoflavones in SCCO₂ with ethanol was correlated with the second virial coefficient. The solubility depended on seventh power of the molar fraction of ethanol in SCCO₂. This suggested that the addition of ethanol facilitated cluster formation of CO₂ molecules in the supercritical phase, enhancing the solubility of isoflavones. A SCCO₂ and ethanol binary system was especially effective in extracting glycoside isoflavones.     

分散染料在超临界CO2中的溶解性研究进展

介绍了目前国内外分散染料在超临界CO2中溶解度的测定装置及其各自的优缺点，同时列出了通过不同的方法测得的分散染料在超临界CO2中的溶解度；分析了计算溶解度的主要模型和影响分散染料在超临界CO2中溶解度的主要因素。     

Fractionation of buffalo butter oil by supercritical carbon dioxide

Buffalo butter oil was fractionated by supercritical carbon dioxide into four fractions (F₁-F₄). Fractionation was performed at 50 and 70 °C over a pressure range of 10.9-40.1 MPa. Short chain fatty acids (C₄-C₈), medium chain fatty acids (C₁₀-C₁₄) and saturated fatty acids were decreased from F₁ to F₄, while long chain fatty acids (C₁₆-C_18:3) and unsaturated fatty acids were increased. Triacylglycerol molecular species exhibited a similar trend as fatty acids. Cholesterol was concentrated in F₁, and with increasing the fluid density, it decreased by more than 50% in F₄. Substantial changes occurred in the chemical composition of the fractions led to distinctive differences in their thermal profile and solid fat content. Fractions obtained in the initial stages of the fractionation exhibited lower melting behavior that obtained in the late stages.     

Extraction of lipids from cherry seed oil using supercritical carbon dioxide

 Cherry seeds (Prunus avium L.) were extracted with compressed carbon dioxide at 313 K and 333 K in the pressure range 18–22 MPa. The influence of superficial velocity was also analysed using values of 0.02, 0.06 and 0.08 cm/s. The extraction yield was increased by a reduction in particle size. The physical and chemical characteristics of the oil were determined. The results, in terms of free fatty acids and sterol compositions, were compared with those obtained when hexane was used as solvent. Other physical and chemical characteristics were also compared with refined hexane-extracted oil. Received: 29 February 2000 / Revised version: 19 April 2999     

Mathematical modelling of soybean oil solubility in supercritical carbon dioxide

The solubility of soybean oil in supercritical carbon dioxide has been determined in the pressure range of 100–300 bar and in the temperature range of 313–323 K. The obtained values (from 0.0005 to 0.02055 g L^?1) have been correlated using four different empirical equations proposed correspondingly by Chrastil, del Valle and Aquilera, Adachi and Lu and Sparks et al. Since the Sparks et al. equation provided the lowest average absolute relative deviation (AARD) (10.25%) than other models in the examined experimental range, a modified equation of Sparks et al. model was developed for predicting the solubility of soybean oil in supercritical carbon dioxide as a function of temperature and density. An improved equation showed the lowest deviation (2.15%) between experimental data than the other empirical equations considered in this study. The proposed equation was also applied for correlating the solubility of linoleic acid (AARD was 2.40%).     

超临界二氧化碳流体中分散染料的溶解性研究

讨论在超临界二氧化碳流体染色体系中循环时间、流体压力、流体温度等工艺因素对分散染料溶解性的影响；并在压力30MPa、温度120℃下，对部分提纯及商品分散染料在超临界二氧化碳流体中的溶解度进行了测试；分析了分散染料结构中取代基对溶解性的影响。     

Response surfaces of hazelnut oil yield in supercritical carbon dioxide

Response Surface Methodology was used to determine the effects of solvent flow rate (1, 3 and 5 g/min), pressure (300, 375 and 450 bar) and temperature (40, 50 and 60 °C) on hazelnut oil yield in supercritical carbon dioxide (SC-CO₂). Oil yield was represented by a second order response surface equation (R²=0.997) using Box-Bhenken design of experiments. Oil yield increased with increasing SC-CO₂ flow rate, pressure and temperature. The maximum oil yield was predicted from the response surface equation as 0.19 g oil/g hazelnut (34% of initial oil) when 4 g hazelnut particles (particle diameter<0.85 mm) were extracted with 5 g/min SC-CO₂ flow rate at 450 bar, and 60 °C for 10 min. Total extraction time at these conditions was predicted to be 35 min.     

Effect of supercritical carbon dioxide treatment on the Maillard reaction in model food systems

The effect of supercritical carbon dioxide treatment on the development of the Maillard reaction in powdered model systems of lactose/ovine caseinmacropeptide and lactose/β-lactoglobulin at different pH values was studied. Supercritical carbon dioxide treatments in static conditions at 30 MPa and 50 °C for up to 5 h were applied to model systems. Control experiments at 50 °C were also performed. All assayed model systems treated with carbon dioxide under supercritical conditions showed lower extent of the Maillard reaction than control treated samples. Differences between supercritical carbon dioxide treated and control samples increased with pH. These results indicate that supercritical carbon dioxide treatment of food samples does not favour the Maillard reaction and thus can be applied in foods that may require special care to avoid excessive loss of available lysine.     

Effects of cosolvents on the decaffeination of green tea by supercritical carbon dioxide

Due to the adverse effects of the caffeine in a variety of plant products, many methods have been explored for decaffeination, in efforts to remove or reduce the caffeine contained in plant materials. In this study, in order to remove caffeine from green tea (Camellia sinensis) leaves, we have employed supercritical carbon dioxide (SC–CO₂), which is known to be an ideal solvent, coupled with a cosolvent, such as ethanol or water. By varying the extraction conditions, changes not only in the amount of caffeine, but also in the quantities of the principal bioactive components of green tea, including catechins, such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC), were determined. The extraction conditions, including temperature, pressure and the cosolvent used, were determined to affect the efficacy of caffeine and catechin extraction. In particular, the type and concentration of a cosolvent used constituted critical factors for the caffeine removal, combined with minimal loss of catechins, especially EGCG. When the dry green tea leaves were extracted with SC–CO₂ modified with 95% (v/v) ethanol at 7.0 g per 100 g of CO₂ at 300 bar and 70 °C for 120 min, the caffeine content in the decaffeinated green tea leaves was reduced to 2.6% of the initial content. However, after the SC–CO₂ extraction, a substantial loss of EGCG, as much as 37.8% of original content, proved unavoidable.     

分散染料在超临界二氧化碳流体中的溶解性

为更好地筛选适用于超临界二氧化碳(ScCO2)流体染色的分散染料,使用状态方程结合基团贡献法和计算化学法,得到不同工况条件及不同染料结构对分散染料在超临界CO2流体中溶解度的影响规律,建立了分散染料在超临界CO2流体中溶解度预测方法.结果表明:不同工况条件会影响分散蓝79染料的溶解度,其中较低的温度和较高的压力对溶解过...     

Extraction and fractionation of alkylresorcinols from triticale bran by two-step supercritical carbon dioxide

Bran from triticale cultivars Ultima and Pronghorn and Canadian Prairie Spring (CPS) wheat were fractionated using a two-step sequential supercritical carbon dioxide (SC-CO₂) extraction technique with and without ethanol to selectively extract and enrich high-value alkylresorcinols (ARs). Pure SC-CO₂ (70 °C; flow rate 25 g/min; pressure 35 MPa), was used for the first extraction step. The non-polar lipids yield ranged from 3.08 to 3.26 g/100 g and they were composed mainly of C18:2 (33-41 g/100 g), C18:1 (15-21 g/100 g), C16:0 (15-19 g/100 g), and C18:3 (4-5 g/100 g) fatty acids. The second extraction step, performed on the bran remaining after the first extraction, was carried out with SC-CO₂ plus 0.5 mL/min ethanol (70 °C; flow rate 5 g/min; pressure 35 MPa). The resulting total polar lipid yield of bran samples ranged between 0.62 and 0.86 g/100 g and the main compounds present in the polar lipids were ARs. The total AR contents of triticale cv Ultima, wheat, and triticale cv Pronghorn were 70, 68 and 36 mg/100 g, respectively. Saturated and unsaturated AR homologues of C15:0, C17:0, C19:0, C19:1, C21:0, C21:1, C23:0 and C25:0 were detected in all samples. Over 98% of the triticale ARs and over 95% of the wheat ARs were extracted under the SC-CO₂ conditions used.     

Deacidification of olive oil by countercurrent supercritical carbon dioxide extraction: Experimental and thermodynamic modeling

Supercritical carbon dioxide was used as an extractive solvent to remove free fatty acids from cold-pressed olive oil. Crude oil of different acidity content (from 0.5 to 4.0 wt%) was extracted in a packed column at 313 K and pressures of 180, 234 and 250 bar. The group contribution equation of state was employed to simulate the separation process, representing the oil as a simple pseudo-binary oleic acid + triolein mixture. Despite the simple representation of oil composition to simulate the deacidification process, a satisfactory agreement between the experimental and calculated yields and acidity of raffinates was obtained. The thermodynamic model was employed to study a continuous countercurrent multistage extraction process which yielded a raffinate having acidity lower than 0.7 wt%, when crude olive oil with different FFA content was processed.     

Drying of foods using supercritical carbon dioxide — Investigations with carrot

The use of supercritical carbon dioxide (scCO₂) for the removal of moisture from cylindrical pieces of carrot has been investigated. The experiments were carried out at 20 MPa pressure and the effects of temperature and co-solvent (ethanol) addition were examined. At the investigated conditions, comparisons with air-drying indicated that drying kinetics and the associated drying mechanisms differed between the techniques. The microstructural characteristics of carrot pieces that had been dried using the different techniques were compared using X-ray microtomography and light microscopy. Carrots dried in the supercritical fluid environment were seen to retain their shape much better than air-dried carrots which underwent shrinkage. Samples dried in ethanol-modified scCO₂ possessed less dense structures and consequently displayed more favourable rehydrated textural properties than the air-dried equivalents.

Industrial relevance

Drying is a common unit operation in food processing, but the rehydrated product is often of very poor quality. Comparatively little work has been done on optimising drying for quality of the final, rehydrated product. Supercritical drying is a possible way of maintaining product microstructure, and this paper describes experiments in which the supercritical drying of carrot is studied and compared with conventional processes.     

Solubility measurement of methyl anthranilate in supercritical carbon dioxide using dynamic and static equilibrium systems

The solubility of methyl anthranilate in supercritical carbon dioxide was determined using dynamic and static equilibrium systems. Three temperatures (40, 60 and 80 °C) and a pressure range between 160 and 340 atm were applied for the dynamic solubility measurements. The flow rate was maintained at 0.5 mL min^?1 in the dynamic solubility measurements, where the solute solubility was claimed to be independent of the flow‐rate factor. Two temperatures (40 and 60 °C) and the pressure range between 100 and 265 atm were used in the static equilibrium system. The crossover pressure region was observed between 220 and 240 atm in the static system, but was not seen in the dynamic system. The solubility of methyl anthranilate determined by the static system was consistently higher than the dynamic solubility measurement, indicating that the static technique provided more reliable solubility data for methyl anthranilate than the dynamic technique. The solubility data obtained with the static system were in good agreement with the predictive models based on the Chrastil equation and the Peng–Robinson equation of state with the Panagiotopoulos and Reid mixing rule. Copyright © 2006 Society of Chemical Industry     

Inactivation and structural change of horseradish peroxidase treated with supercritical carbon dioxide

The influence of supercritical carbon dioxide (SCCO₂) at 55 °C on inactivation of horseradish peroxidase (HRP) in buffer solution, pH 5.6, was studied while its structural change was analyzed by far UV-circular dichroism (CD) and tryptophan fluorescence spectroscopy. SCCO₂ treatment had significant effects on the residual activity of HRP, the least residual activity was only 12% at 30 MPa. HRP’s secondary and tertiary structures were changed. The α-helix relative content in the secondary structure decreased and the intrinsic relative fluorescence intensity (RFI) increased as the pressure of SCCO₂ treatment was elevated. The HRP’s inactivation closely corresponded to the loss of α-helix relative content and the increase of RFI. After a 7-day storage at 4 °C, the restoration of residual activity and the reversion of the α-helix relative content were observed while RFI resumed with exception of the 30 MPa treatment.     

Effects of supercritical carbon dioxide extraction conditions on yields and antioxidant activity of Chlorella pyrenoidosa extracts

Yields and antioxidant activity of Chlorella pyrenoidosa extracts obtained by supercritical carbon dioxide extraction through an orthogonal experiment (L₁₆(4⁵)) were investigated to get the best extraction conditions. The results showed that extraction pressure, temperature and modifier were the main three variables that influenced the yields of extracts. The highest yield was obtained at 32 °C, 40 MPa, 20 L h⁻¹ with dosage of modifier 1 mL ethanol g⁻¹ sample for 3 h. Moreover, increasing pressure and concentrations of modifier led to the increase of extraction yields and antioxidant activity. DPPH radical scavenging method showed that almost all the extracts had significantly higher antiradical activities varying from 29.67 ± 0.29% to 54.16 ± 4.49% comparing to -tocopherol, Trolox, and BHT as references except extracts at 32 °C, 35 MPa and 15 L h⁻¹ without modifier for 1.5 h. These results indicate that supercritical extraction is a promising alternative process for recovering compounds of high antioxidant activity from C. pyrenoidosa.     

Extraction of coffee diterpenes and coffee oil using supercritical carbon dioxide

Commercial green and roasted coffee beans were used to maximize oil extraction and conditions were studied to obtain the highest and lowest diterpene levels on green and roasted coffee oil, respectively. Thus, operational temperatures (60–90 °C) and pressure (235–380 bar) were optimized for coffee oil extraction. Oil content levels and diterpene oil concentration were compared to the results obtained with the extraction with Soxhlet apparatus, using hexane as solvent. In general, an inverse correlation was observed between the amount of extracted oil and diterpene concentration levels. As a result, different oil contents with different diterpene concentrations could be obtained. The HPLC analysis of cafestol and kahweol in the oil extracted from green coffee beans at 70 °C/253 bar resulted in the highest concentration (453.3 mg 100 g⁻¹), which was 48% lower than in the oil extracted with hexane while in the oil extracted from roasted coffee beans at 70 °C/371 bar, resulted in 71.2% reduction of diterpenes.     

Inactivation of polyphenol oxidases in cloudy apple juice exposed to supercritical carbon dioxide

The inactivation of polyphenol oxidase (PPO) in cloudy apple juice exposed to supercritical carbon dioxide (SCCO₂) treatment was investigated. Higher pressure, higher temperature, and longer treatment time caused more inactivation of PPO. The maximum reduction of PPO activity reached more than 60% at 30 MPa and 55 °C for 60 min. The experimental data followed first-order reaction kinetics; the kinetic rate constant k and the decimal reduction time D were closely related to the pressure and temperature of SCCO₂ treatment. Higher pressures or higher temperatures resulted in lower D values (higher k), the D value of PPO was minimized to 145 min treated by the combination of 30 MPa and 55 °C. Activation energy of 18.00 kJ /mol, was significantly reduced by SCCO₂ treatment at 30 MPa, as compared to activation energy of 72.0 kJ/mol for identical treatment at atmospheric pressure. Pressure and temperature sensitivity of kinetic parameters were studied. Z_P at 55 °C was 66.7 MPa and Z_T at 30 MPa was 108 °C.