Supercritical fluid extraction of fish oil from fish by-products: A comparison with other extraction methods

Fish and fish by-products are the main natural source of omega-3 polyunsaturated fatty acids, especially EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), both of them with a great importance in the food and pharmaceutical industries. Comparing to conventional fish oil extraction processes such as cold extraction, wet reduction or enzymatic extraction, supercritical fluid extraction with carbon dioxide under moderate conditions (25 MPa and 313 K) may be useful for reducing fish oil oxidation, especially when fish oil is rich in omega-3 such as salmon oil, and the amount of certain impurities, such as some species of arsenic. Furthermore, taking profit of the advantages of supercritical carbon dioxide as extractive solvent, a coupled extraction-fractionation process is proposed as a way to remove free fatty acids and improve fish oil quality, alternatively to physical and chemical refining procedures.     

Determination of acrylamide in coffee and chocolate by pressurised fluid extraction and liquid chromatography-tandem mass spectrometry

A selective and sensitive procedure has been developed and validated for the determination of acrylamide in difficult matrices, such as coffee and chocolate. The proposed method includes pressurised fluid extraction (PFE) with acetonitrile, florisil® clean-up purification inside the PFE extraction cell and detection by liquid chromatography (LC) coupled to atmospheric pressure ionisation in positive mode tandem mass spectrometry (APCI-MS-MS). Comparison of ionisation sources (atmospheric pressure chemical ionisation (APCI), atmospheric pressure photoionization (APPI) and the combined APCI/APPI) and clean-up procedures were carried out to improve the analytical signal. The main parameters affecting the performance of the different ionisation sources were previously optimised using statistical design of experiments (DOE). PFE parameters were also optimised by DOE. For quantitation, an isotope dilution approach was used. The limit of quantification (LOQ) of the method was 1 µg kg^-1 for coffee and 0.6 µg kg^-1 for chocolate. Recoveries ranged between 81-105% in coffee and 87-102% in chocolate. The accuracy was evaluated using a coffee reference test material FAPAS T3008. Using the optimised method, 20 coffee and 15 chocolate samples collected from Valencian (Spain) supermarkets, were investigated for acrylamide, yielding median levels of 146 µg kg^-1 in coffee and 102 µg kg^-1 in chocolate.     

烟草二氧化碳超临界萃取物的初步研究

初步探索了二氧化碳超临界流体萃取烟草成分的技术参数,采用气相色谱仪和气质联用仪分析了烟草萃取物.结果表明,二氧化碳超临界萃取物以非极性和弱极性化合物为主.另外对上海烟草(集团)公司的4种牌号卷烟产品萃取物的相对定量分析结果表明,"中华"牌卷烟的萃取物含量最高,"双喜"次之,"牡丹"第三,"前门"的最低.     

Impact of the roasting degree of coffee on the in vitro radical scavenging capacity and content of acrylamide

Due to the recognized toxicity of acrylamide, intensive efforts have been made to reduce the concentration of this undesired Maillard by-product in food. This work reports the results obtained from a series of experiments aimed at determining the concentration of acrylamide and the in vitro radical scavenging capacity in the same roasted and ground coffee samples, as it is well established that a significant part of the antioxidant activity in coffee is linked to the melanoidins, which are also considered as Maillard reaction products (MRPs). The radical scavenging capacity was measured using electroparamagnetic resonance (EPR). Coffee samples from the Robusta and Arabica varieties were roasted at 236 °C over different time periods to obtain very light, light, medium and dark roast. Color analyses were performed on all samples. Increasing the roasting degree led to a decrease in acrylamide concentration as well as radical scavenging capacity. The results of this work indicate that any mitigation efforts must also take into account the potential loss of desired food constituents and consequently changes to the risk/benefit characteristics of foods.     

Supercritical fluid extraction of carotenoids from Scenedesmus almeriensis

Scenedesmus almeriensis is a fast-growing highly productive new strain and is also a good producer of lutein.     

Supercritical carbon dioxide extraction of the residual oil from palm kernel cake

Palm kernel cake contains residual oil that has never been retrieved and it is treated as wastes. In this study, supercritical carbon dioxide was used to separate the oil from the palm kernel matrix. The studied extraction parameters were at the set pressures 27.57, 34.47 and 41.36 MPa, temperatures 40-70 °C and carbon dioxide flow rate between 1 and 3 ml/min. The effect of the particle size on the oil yield was examined using different particle size that separated by sieving from ?106, ?150, ?180, ?250 and ?450 μm. The results showed that the highest oil removed was 9.26 g oil/100 g sample (p < 0.05) for the particle ?150 μm, and under extraction temperature of 70 °C, pressure 41.36 MPa, and carbon dioxide flow rate of 2 ml/min. The experimental results indicate that supercritical carbon dioxide extraction could be a viable technique to remove the remaining oil and to produce defatted palm kernel cake.     

Supercritical fluid extraction of grape seed: Process scale-up, extract chemical composition and economic evaluation

The scale-up of the supercritical fluid extraction (SFE) process for grape (Vitis vinifera L.) seed was studied from the laboratory (0.29 L) to the pilot scale (5.15 L) at 35 MPa and 313 K. The scale-up criterion adopted consisted of maintaining a constant solvent to feed ratio (S/F), and the criterion was successfully used to predict the approximate behavior of the SFE process from the laboratory at the pilot scale for a 17-fold scale-up. Linoleic acid was the major component of the extract; palmitic, stearic and oleic acids were also detected. The economic evaluation showed that it is viable to establish a SFE plant in Brazil for SFE processing of grape seed. From the technical-economic evaluation, for SFE of grape seed at 313 K/35 MPa, an extraction time of 240 min and S/F of 6.6 produced the best relationship between yield and cost.     

Pressurized fluid extraction of pistachio oil using a modified supercritical fluid extractor and factorial design for optimization

A pressurized fluid extraction (PFE) method for the extraction of pistachio oil was developed mainly as an analytical tool to determine oil content and/or its quality. The supercritical fluid extractor was modified to be able to pump liquid solvent and CO₂ into the extraction vessel alternatively. The extraction yield was found independent of the pressure in the range 10-150 bar tested. The addition of crushed glass increased the extraction yield by more than 15 g/100 g, while the extraction reproducibility expressed by percentage RSD was improved from 4 to 1. Furthermore, the use of crushed glass reduced the solvent consumption from 35 to 20 mL. The effective variables of temperature (40-80 °C), solvent volume (5-25 mL), and crushed glass percentage (30-60 g/100 g) were optimized by a factorial design method. The model allows the prediction of the extraction yield at different conditions. The PFE yield (i.e. 52.6 g/100 g) and fatty acid composition of pistachio oil were found similar to Soxhlet extraction and their variations were within the experimental uncertainty verified by statistical t-test analysis. Two different solvents of n-hexane and ethanol were used for PFE of pistachio oil. The extraction yield was about one-third (i.e. 18 g/100 g) when ethanol was used as solvent.     

Determination of acrylamide in foods by pressurized fluid extraction and liquid chromatography-tandem mass spectrometry used for a survey of Spanish cereal-based foods

An automated and rapid method for the determination of acrylamide in different food products is presented. The method involves pressurized fluid extraction (PFE) of foods with acetonitrile and precipitation with Carrez reagents. The final extract is analysed by liquid chromatography coupled to electrospray ionization tandem mass spectrometry (ESI-MS-MS). The main parameters affecting the performance of ESI-MS-MS and PFE were optimized using a design of experiments approach. The limit of quantification of the method was 5 µg kg^-1, and recoveries from incurred samples ranged between 93 and 101%. The accuracy was evaluated using the reference test materials FAPAS T3002, T3005 and T3011. Using the optimized method, 62 food samples of potato chips, snacks, biscuits, breakfast cereals and crisp bread sampled from Valencia, Spain, supermarkets were surveyed for acrylamide levels. The levels were similar to those reported in the European Union and USA.     

Supercritical fluid extraction and microencapsulation of bioactive compounds from red pepper (Capsicum annum L.) by-products

The objective of this work was to obtain and stabilize natural vitamins from red pepper by-products. The method of obtainment was supercritical carbon dioxide extraction, studying different parameters that affect the yield. The highest extraction yield was found at 60 °C, 24 MPa extraction, with no modifier added and 0.2–0.5 mm particle size. The recovered extract was a red-coloured oil. The extract was subsequently microencapsulated by spray-drying using gum arabic as wall material to avoid the degradation of vitamin over the storage time. The thermal stability of microcapsules was analysed by thermal gravimetric analysis (TGA), while size, shape and morphology of microcapsules were studied by scanning electron microscopy (SEM). The microcapsules containing pepper extract were particles of spherical shape with dents on the surface, the average size of these particles was 5.46 μm.     

Supercritical fluid extraction of Coriandrum sativum and subsequent separation of isocoumarins by high-speed counter-current chromatography

A novel supercritical fluid extraction (SFE) method has been developed for extracting essential oil from the aerial part of Coriandrum sativum. Various experimental conditions were investigated to optimise the SFE. It suggested that the extraction of 35 °C, 8 MPa, 2 h might be the optimisation to get the maximum of coriander essential oil. Then, high-speed counter-current chromatography (HSCCC) was successfully used in one step for the isolation and purification of coriandrone B, coriandrin, dihydrocoriandrin and coriandrone A from the coriander oil with a two-phase system composed of n-hexane–ethyl acetate–methanol–water (3:7:5:5, v/v/v/v) for the first time. High-performance liquid chromatography (HPLC) was employed to analyse the HSCCC fractions and revealed that the purities of the isocoumarins were all above 90%, and the chemical structures were identified by spectroscopic analysis including ESIMS, ¹H NMR and UV.     

超临界流体萃取技术在农产品加工业中的应用进展

超临界流体萃取技术是一种清洁、高效的分离方法,具有操作条件温和、无溶剂残留、分离效率高等特点,正受到越来越广泛的关注。本文简要介绍了超临界流体萃取的基本原理、影响超临界流体萃取的因素以及超临界流体萃取技术在农产品加工业中的应用,并对超临界流体萃取技术与其他高新技术联用情况进行了概述与展望,以期为超临界流体萃取技术在农产品加工业的进一步研究与应用提供参考和借鉴。     

Supercritical fluid and solid–liquid extraction of phenolic antioxidants from grape pomace: a comparative study

Distilled white grape pomace (Vitis vinifera var. Garnacha) was subjected to extraction by using two different methods: (1) solid–liquid extraction (SLE) employing 96% ethanol and water and (2) supercritical extraction (SFE) by running carbon dioxide coupled with ethanol as a modifier. Higher phenolic concentrations of extracts were attained by SFE (∼400 ppm), doubling those obtained by SLE. In the latter, increasing values of both temperature (from 25 to 50 °C) and contact time (from 30 to 90 min) and lower solvent-to-solid ratios (from 5:1 to 1:1) resulted in an enhancement of extraction efficiency. In SFE, the addition of the modifier (8%) was also found to favour the release of phenolic compounds. Antiradical activity values—evaluated by the ability to scavenge DPPH radicals—were, as general, also higher for SFE extracts, although maximum values reached at were similar (73% inhibition versus 68%). Chromatographic profiles confirmed the diverse nature of phenolic species occurring in extracts obtained from both extraction methods. Extracts from SLE contained more proanthocyanidins, whereas SFE ones contained basically gallic acid, catechin and epicatechin. Protection against oil oxidation assayed with two samples confirmed these results.     

Supercritical carbon dioxide fluid extraction of Hibiscus cannabinus L. seed oil: A potential solvent-free and high antioxidative edible oil

The supercritical fluid extraction (SFE) trends and antioxidant activities of Hibiscus cannabinus seed oils were studied. SFE results indicate that extraction pressure is the major factor determining the oil yield. In comparison, classic Soxhlet extraction (SOX/L) yielded higher oil content than SFE (P < 0.05). However, no significant differences in oil content were observed in SFE at 600 bars/80 °C, rapid Soxhlet extraction (SOX/S) and conventional ultra-sonic assisted solvent extraction (SONIC) (P > 0.05). Antioxidant activities of H. cannabinus seed oils were compared with 7 types of commercial edible oils. DPPH scavenging activity test indicated that H. cannabinus seed oil extracted by SFE at 200 bars/80 °C possessed the highest antiradical activity whereas beta-carotene bleaching (BCB) assay revealed that all H. cannabinus seed oils (except for SFE at 400 bars/80 °C and 600 bars/80 °C) exhibited higher antioxidant activity than all commercial edible oils (P < 0.05). Thus, SFE – H. cannabinus seed oil may serve as an excellent source of solvent-free edible oil with high antioxidant properties.     

Supercritical fluid extraction of antioxidant and antimicrobial compounds from Laurus nobilis L. Chemical and functional characterization

Extraction of laurel leaves by using supercritical carbon dioxide was carried out on a supercritical fluid (SF) pilot-scale plant. The extraction pressure and temperature were set to 250 bar and 60°C, respectively, using a 4% of ethanol as modifier. The employed apparatus, owing to a two-stage separation, allowed us to obtain two different fractions (F1 and F2), whose antioxidant and antimicrobial activities were investigated. Two different methods, β-carotene bleaching test and DPPH^• free radical–scavenging assay, were carried out to determine the antioxidant activity. Moreover, antimicrobial activity of laurel fractions was tested against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 10145, Escherichia coli ATCC 11775, Candida albicans ATCC 60193 and Aspergillus niger ATCC 16404. Minimum inhibitory concentration (MIC) and minimal bactericidal and fungicidal concentration (MBC) were obtained. Both fractions showed a similar antioxidant activity, although it was slightly higher for the fraction recovered in separator 2. However, antimicrobial activity against the microorganisms tested was only found when fraction 2 was used. Staphylococcus aureus was the most sensitive microorganism to this fraction, with maximal inhibition zones (25 mm) and the lowest MBC values (1.25 mg/ml), whereas the least susceptible was the fungi Aspergillus niger. In order to determine the compounds responsible for the antimicrobial activity, fraction 2 was analysed by GC–MS; results obtained showed that most of the compounds identified in the supercritical extract have been previously described to show antimicrobial activity; among them, the major compound found in the supercritical extract corresponded to a sesquiterpene lactone of the germacrolide type (6-epi-desacetyllaurenobiolide) previously described in laurel.     

Comparison of essential oils of clove buds extracted with supercritical carbon dioxide and other three traditional extraction methods

Supercritical fluid extraction (SFE) of essential oil from clove buds with CO₂ was explored. The effect of different parameters, such as temperature (30 °C, 40 °C, 50 °C), pressure(10 MPa, 20 MPa, 30 MPa) and particle size (three degree index), on the extraction yield and the content of eugenol in extracts was investigated using three-level orthogonal array design. The experimental results show that the temperature has the largest effect on the eugenol content of the extracts, and particle size has the maximum effect on the oil yield. The essential oil of 19.56% yield, in which the maximum content of eugenol in extracts is 58.77%, can be extracted from clove buds at pressure of 10 MPa and temperature of 50 °C. Essential oil of clove buds obtained by SFE, hydrodistillation, steam distillation and Soxhlet extraction were further analyzed by gas chromatography/mass spectrometric detection to compare the extraction methods. Twenty three compounds in the clove oils have been identified, showing that the composition of the clove oil extracted by different methods is mostly similar, whereas relative concentration of the identified compounds is apparently different. General characteristics of the clove oils obtained by different methods were further compared, and SFE is considered as the optimum process among the four processes for obtaining clove oil with high quality.     

CO2超临界流体代替水作介质铬鞣机理的研究(3)--CO2超临界流体条件下铬鞣初始pH值和温度的优化

利用自制的CO2超临界流体制革设备，考察了CO2超临界流体代替水作介质条件下的铬鞣因素：初始pH值和温度的影响。通过对各实验条件下坯革的收缩温度、铬含量、铬的渗透以及革坯的状态等进行评价鞣制效果，得到了在CO2超临界流体条件下的铬鞣的最佳初始pH值为3．5，最佳鞣制温度为34℃。     

Impact of extraction conditions on the content of acrylamide in model systems and food

It has recently been suggested that the analytical methods that have been developed to date for the determination of acrylamide (AA) may underestimate the concentration of AA in certain foods, because significantly higher results were obtained upon extraction of the food matrix under alkaline conditions. The present study employs food (potato, rye) and chemical model systems to better understand the tentative release of AA under high pH extraction conditions. The experimental design is based on the generation of AA in an environment containing an AA-isotopomer, and by comparing the ratio of AA, respectively the AA-isotopomer, after extraction at pHs 7 and 12. The results show that the additional AA released is not due to improved extractability of AA from the food matrix, and should therefore be regarded as an extraction artefact. Strongly alkaline conditions seem to induce net formation of AA from water-soluble precursors formed during thermolysis.     

超临界萃取技术及其在啤酒花浸膏生产上的应用

随着科学技术的发展,超临界流体萃取技术以其独特的优势越来越受到人们的关注。对超临界流体萃取技的发展概况、原理、应用以及未来发展做了简单介绍,并着重叙述了其在啤酒花浸膏的生产过程中的应用。