Development and validation of a subcritical 1,1,1,2-tetrafluoroethane extraction technique: Gas chromatography-mass spectrometry method for the simultaneous determination of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polybrominated biphenyl ethers in aquatic products.

A simple, rapid, and green method was developed for the simultaneous analysis of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polybrominated biphenyl ethers in aquatic products using subcritical 1,1,1,2-tetrafluoroethane extraction coupled with gas chromatography and mass spectrometry. Effects of the extraction temperature, pressure, and cosolvent volume on the extraction efficiency were investigated by extracting spiked oyster samples. The results show that the maximum extraction efficiency was obtained at 40°C, 12 MPa, and a cosolvent (dichloromethane) volume of 5.0 mL. Under these conditions, the calibration curves had good linearity with square of the correlation larger than 0.998 in the concentration range of 5-800 ng/mL; limit of detection and limit of quantitation were 0.16-2.83 and 0.55-9.43 ng/g, respectively. At spiked levels of 10, 30, and 50 ng/g, the average recoveries were 70.4-80.4% for polycyclic aromatic hydrocarbons, 74.0-83.6% for polychlorinated biphenyls, and 66.9-78.0% for polybrominated biphenyl ethers, with average relative standard deviations of less than 16.3%. The established method has no significant differences in recovery compared to traditional methods and is suitable for the analysis of real samples.

Subcritical Fluid Extraction of Chinese Quince Seed: Optimization and Product Characterization.

Chinese quince seed (CQS) is an underutilized oil source and a potential source of unsaturated fatty acids and α-tocopherol-rich oil. Subcritical fluid (SCF) extraction is executed at lower pressures and temperatures than the pressures and temperatures used in supercritical fluid extraction. However, no studies on the SCF extraction of CQS oil are reported. Therefore, the objective of this study was to evaluate the use of SCF for the extraction of CQS oil and to compare the use of SCF with the classical Soxhlet (CS) and supercritical CO2 (SC-CO2) extraction methods. Response surface methodology (RSM) was used to investigate the extraction conditions: temperature (45-65 °C), time (30-50 min), and solvent/solid ratio (5-15 mL/g). The optimization results showed that the highest yield (27.78%) was obtained at 56.18 °C, 40.20 min, and 12.57 mL/g. The oil extracted by SCF had a higher unsaturated fatty acid content (86.37%-86.75%), higher α-tocopherol content (576.0-847.6 mg/kg), lower acid value (3.97 mg/g), and lower peroxide value (0.02 meq O2/kg) than extractions using CS and SC-CO2 methods. The SCF-defatted meal of oilseed exhibited the highest nitrogen solubility index (49.64%) and protein dispersibility index (50.80%), demonstrating that SCF extraction was a promising and efficient technique as an alternative to CS and SC-CO2 methods, as very mild operating conditions and an eco-friendly solvent can be used in the process with maximum preservation of the quality of the meal.

Recovery of Oil with Unsaturated Fatty Acids and Polyphenols from Chaenomelessinensis (Thouin) Koehne: Process Optimization of Pilot-Scale Subcritical Fluid Assisted Extraction.

The potential effects of three modern extraction technologies (cold-pressing, microwaves and subcritical fluids) on the recovery of oil from Chaenomelessinensis (Thouin) Koehne seeds have been evaluated and compared to those of conventional chemical extraction methods (Soxhlet extraction). This oil contains unsaturated fatty acids and polyphenols. Subcritical fluid extraction (SbFE) provided the highest yield-25.79 g oil/100 g dry seeds-of the three methods. Moreover, the fatty acid composition in the oil samples was analysed using gas chromatography-mass spectrometry. This analysis showed that the percentages of monounsaturated (46.61%), and polyunsaturated fatty acids (42.14%), after applying SbFE were higher than those obtained by Soxhlet, cold-pressing or microwave-assisted extraction. In addition, the oil obtained under optimized SbFE conditions (35 min extraction at 35 °C with four extraction cycles), showed significant polyphenol (527.36 mg GAE/kg oil), and flavonoid (15.32 mg RE/kg oil), content, had a good appearance and was of high quality.

Optimization of subcritical fluid extraction of carotenoids and chlorophyll a from Laminaria japonica Aresch by response surface methodology.

BACKGROUND: The carotenoids and chlorophyll a of Laminaria japonica Aresch were extracted using ethanol-modified subcritical 1,1,1,2-tetrafluoroethane (R134a). In the present study, the effects of pressure (5-17 MPa), temperature (303-333 K) and the amount of cosolvent(2-6% R134a, w/w)were investigated. Response surface methodology (RSM) combined with a Box-Behnken design was applied to evaluate the significance of the three independent variables on each response. A desirability function was conducted to simultaneously optimize the multiple responses. RESULTS: The optimum extraction conditions were as follows: extraction temperature 324.13 K, extraction pressure 17 MPa and a cosolvent amount of 4.73%. Under these conditions, the yields of carotenoids and chlorophyll a were predicted to be 0.239 and 2.326 g kg(-1), respectively. CONCLUSION: It has been proved that subcritical R134a is a potential solvent, which can be an alternative to supercritical CO2 for extraction of natural ingredients under mild conditions.

Effect of microwave (MW)-subcritical extraction on oil recovery, oxidative stability, and lipid types from Katsuwonus pelamis livers.

Katsuwonus pelamis is a tuna species mostly sold for canned fillets, its livers were lack of utilization. This study thus investigated an oil production method combining microwave (MW) pretreatment and subcritical dimethyl ether (SDME) in aim to reach improved efficiency and oil quality. The heating characteristics from different MW powers (400, 600, and 800 W) were evaluated, and SEM showed MW having hydrolysis effect on matrix lipoprotein, the fortified recovery rate was also found. Under the MW-SDME condition with 600 W power, 1:5 solid-to-liquid ratio, and 100 min, the recovery reached 93.21% in maximal (SDME ∼50%). To further improve quality, MW powers was noticed affecting lipid types, fatty acid composition, and oxidative stability of produced oils. 1286 lipid types (mostly glyceride and phospholipid-type) were identified, while higher MW lowered the emulsifying phospholipids prompting phase separation. Several oxidation indexes consistently increased with the rising MW power, GC-MS suggested 400 W for higher DHA.

Sustainable Green Extraction of Carotenoid Pigments: Innovative Technologies and Bio-Based Solvents.

Carotenoids are ubiquitous and versatile isoprenoid compounds. The intake of foods rich in these pigments is often associated with health benefits, attributable to the provitamin A activity of some of them and different mechanisms. The importance of carotenoids and their derivatives for the production of foods and health-promotion through the diet is beyond doubt. In the new circular economy paradigm, the recovery of carotenoids in the biorefinery process is highly desirable, for which greener processes and solvents are being advocated for, considering the many studies being conducted at the laboratory scale. This review summarizes information on different extraction technologies (ultrasound, microwaves, pulsed electric fields, pressurized liquid extraction, sub- and supercritical fluid extraction, and enzyme-assisted extraction) and green solvents (ethyl lactate, 2-methyltetrahydrofuran, natural deep eutectic solvents, and ionic liquids), which are potential substitutes for more toxic and less environmentally friendly solvents. Additionally, it discusses the results of the latest studies on the sustainable green extraction of carotenoids. The conclusions drawn from the review indicate that while laboratory results are often promising, the scalability to real industrial scenarios poses a significant challenge. Furthermore, incorporating life cycle assessment analyses is crucial for a comprehensive evaluation of the sustainability of innovative extraction processes compared to industry-standard methods.

Enhancement of Lipid Extraction from Soya Bean by Addition of Dimethyl Ether as Entrainer into Supercritical Carbon Dioxide.

Soya beans contain a variety of lipids, and it is important to selectively separate neutral lipids from other lipids. Supercritical carbon dioxide extraction has been used as an alternative to the selective separation of neutral lipids from soya beans, usually using non-polar hexane. However, supercritical carbon dioxide extraction has a high operating pressure of over 40 MPa. On the other hand, liquefied dimethyl ether extraction, which has attracted attention in recent years, requires an operating pressure of only 0.5 MPa, but there is concern about the possibility of an explosion during operation because it is a flammable liquefied gas. Therefore, this study aims to reduce the operating pressure by using a non-flammable solvent, supercritical carbon dioxide extraction mixed with liquefied dimethyl ether as an entrainer. The extraction rate and the amount of neutral lipids extracted increased with increasing amounts of added liquefied dimethyl ether. In the mixed solvent, the amount of neutral lipids extracted was higher at an operating pressure of 20 MPa than in pure supercritical carbon dioxide extraction at 40 MPa. The mixing of liquefied dimethyl ether with supercritical carbon dioxide allowed an improvement in the extraction of neutral lipids while remaining non-flammable.

Subcritical Fluid Extraction of Antioxidant Phenolic Compounds from Pistachio (Pistacia vera L.) Nuts: Experiments, Modeling, and Optimization.

A process to obtain phenolic compounds with antioxidant properties from pistachio nuts using water/ethanol mixture under high temperature and pressure conditions was carried out. To optimize extraction conditions and antioxidant activity of bioactive compounds, theoretical models were scanned against experimental data. Phenolic profile was dominated by several flavonoids and gallic acid derivatives. A fitted model for phenolic compounds extraction presented a maximum predicted value under the following conditions: 220 °C extraction temperature, 6.5 MPa pressure, and 50% ethanol. Beneath these conditions, phenolic extracts gave the highest radical scavenging capacity, similar to that reached by using commercial antioxidants. A mathematical model, namely two-site desorption kinetic model, showed to be suitable for the description of extraction kinetics under the optimal operation conditions. Overall, the process described in this study shows a potential alternative method for extraction of pistachio bioactive compounds. PRACTICAL APPLICATION: Pistachio nuts are known to contain a vast array of phenolic and polyphenolic substances having strong antioxidant properties. Currently, the use of natural antioxidants in the food industry has increased, in consequence there is a growing interest in improving the extraction processes using GRAS (general recognize as safe) solvents. This study describes a safe, inexpensive, and short-time method (subcritical fluid extraction) to obtain antioxidant extracts from defatted pistachio nuts. This type of process may be adapted toward applications at industrial scale.

Selective enrichment in bioactive compound from Kniphofia uvaria by super/subcritical fluid extraction and centrifugal partition chromatography.

Nowadays, a large portion of synthetic products (active cosmetic and therapeutic ingredients) have their origin in natural products. Kniphofia uvaria is a plant from Africa which has proved in the past by in-vivo tests an antioxidant activity due to compounds present in roots. Recently, we have observed anthraquinones in K. uvaria seeds extracts. These derivatives are natural colorants which could have interesting bioactive potential. The aim of this study was to obtain an extract enriched in anthraquinones from K. uvaria seeds which mainly contains glycerides. First, the separation of the seed compounds was studied by using supercritical fluid chromatography (SFC) in the goal to provide a rapid quantification method of these bioactive compounds. A screening of numerous polar stationary phases was achieved for selecting the most suited phase to the separation of the four anthraquinones founded in the seeds. A gradient elution was optimized for improving the separation of the bioactive compounds from the numerous other families of major compounds of the extracts (fatty acids, di- and triglycerides). Besides, a non-selective and green Supercritical Fluid Extraction (SFE) with pure CO2 was applied to seeds followed by a Centrifugal Partition Chromatography (CPC). The CPC system was optimized by using the Arizona phase system, to enrich the extract in anthraquinones. Two systems were selected to isolate the bioactive compounds from the oily extract with varied purity target. The effect of the injection mode for these very viscous samples was also studied. Finally, in order to directly apply a selective process of extraction to the seeds, the super/subcritical fluid extraction was optimized to increase the anthraquinone yield in the final extract, by studying varied modifier compositions and nature, as well as different temperatures and backpressures. Conditions suited to favour an enrichment factor bases on the ratio of anthraquinone and trilycerides extracted are described.

Subcritical extraction of flaxseed oil with n-propane: Composition and purity.

Flaxseed (Linum usitatissimum L.) oil was obtained via subcritical n-propane fluid extraction (SubFE) under different temperatures and pressures with an average yield of 28% and its composition, purity and oxidative stability were compared to oils obtained via conventional solvent extraction methods (SEMs). When the oxidative stability was measured by differential scanning calorimetry, the oil was found to be up to 5 times more resistant to lipid oxidation as compared to the SEM oils. Direct infusion electrospray ionization mass spectrometry (ESI-MS) analysis showed characteristic and similar TAG profiles for SubFE and SEMs oils but higher purity for the SubFE oil. The flaxseed oil content of ß-tocopherol, campesterol, stigmasterol and sitosterol were quantified via GC-MS. SubFE showed to be a promising alternative to conventional SEM since SubFE provides an oil with higher purity and higher oxidation stability and with comparable levels of biologically active components.