This review provides an updated overview of the most important applications of supercritical fluids in the extraction of bioactive compounds from plant matrices The main factors influencing the extraction yields, solubility, and manufacturing costs are described Aspects concerning the operational processing in the extraction and fractionation are also discussed The data compiled herein are focused on the extraction of essential oils, phenolic compounds, carotenoids, tocopherols, and tocotrienols

Supercritical Fluid Extraction of Bioactive Compounds: Fundamentals, Applications and Economic Perspectives

Carbon dioxide (CO2) is the major contributor to greenhouse gas (GHG) emissions and the main driver of climate change. Currently, CO2 utilization is increasingly attracting interest in processes like enhanced oil recovery and coal bed methane and it has the potential to be used in hydraulic fracturing processes, among others. In this review, the latest developments in CO2 capture, utilization, conversion, and sequestration are examined through a multi-scale perspective. The diverse range of CO2 utilization applications, including mineralization, biological utilization, food and beverages, energy storage media, and chemicals, is comprehensively presented. We also discuss the worldwide research and development of CO2 utilization projects. Lastly, we examine the key challenges and issues that must be faced for pilot-scale and industrial applications in the future. This study demonstrates that CO2 utilization can be a driver for the future development of carbon capture and utilization technologies. However, considering the amount of CO2 produced globally, even if it can be reduced in the near-to mid-term future, carbon capture and storage will remain the primary strategy and, so, complementary strategies are desirable. Currently, the main CO2 utilization industry is enhanced oil and gas recovery, but considering the carbon life cycle, these processes still add CO2 to the atmosphere. In order to implement other CO2 utilization technologies at a large scale, in addition to their current technical feasibility, their economic and societal viability is critical. Therefore, future efforts should be directed toward reduction of energy penalties and costs, and the introduction of policies and regulation encouraging carbon capture, utilization and storage, and increasing the public acceptance of the strategies in a complementary manner.

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Recent advances in carbon dioxide utilization

Supercritical fluid technologies offer a propitious method for drug discovery from natural sources. Such methods require relatively short processing times, produce extracts with little or no organic co-solvent, and are able to extract bioactive molecules whilst minimising degradation. Supercritical fluid extraction (SFE) provides a range of benefits, as well as offering routes to overcome some of the limitations that exist with the conventional methods of extraction. Unfortunately, SFE-based methods are not without their own shortcomings; two major ones being: (1) the high establishment cost; and (2) the selective solvent nature of CO2, i.e., that CO2 only dissolves small non-polar molecules, although this can be viewed as a positive outcome provided bioactive molecules are extracted during solvent-based SFE. This review provides an update of SFE methods for natural products and outlines the main operating parameters for extract recovery. Selected processing considerations are presented regarding supercritical fluids and the development and application of ultrasonic-assisted SFE methods, as well as providing some of the key aspects of SFE scalability.

Solvent Supercritical Fluid Technologies to Extract Bioactive Compounds from Natural Sources: A Review.

Catechins: Sources, extraction and encapsulation: A review

High-pressure treatments are receiving a great deal of attention for the inactivation of micro-organisms in foodstuff processing, pressure instead of temperature is used as stabilizing factor. In this context, high hydrostatic pressure treatment is the most studied alternative process, many works reported successful results in inactivating a wide range of micro-organisms under different operative conditions such as temperature, cycles of pressure, exposure time. Furthermore, a number of processes using high pressure treatment (HPT) has already been put into the market. Nevertheless this new technology presents the main limitation to be very expensive and difficult to control and manage because of the extremely high pressure employed, so that the widespread industrial diffusion in industry field appears cumbersome. The treatment with supercritical CO 2 could become a relevant alternative to HPT in the field of microbial inactivation of food as well as an innovative technique for the sterilization of thermally and hydrolytically sensitive polymeric materials in biomedical applications, such as polymeric particles for drug delivery or polymeric implants. It has been demonstrated that the effect of microbial inactivation assuring healthy food preservation is already consistent at pressures moderated (lower than 200 bar) when compared with those employed by traditional hydrostatic-pressure HPT methods (2000–7000 bar). In this work the anti-microbial potential of compressed CO 2 was investigated against gram-negative bacteria, gram-positive bacteria and spores; as model species, Pseudomonas aeruginosa , Bacillus subtilis and spores of B. subtilis were used. The experiments were performed in a semi-continous apparatus at different but mild operative conditions. Excellent results were obtained for micro-organisms, under appropriate conditions the survival ratio of bacteria could be reduced to about seven orders of magnitude. Inactivation of spores under the same conditions, found to be conflicting in open literature, was not satisfactory. Spore inactivation was possible by coupling combination of higher temperature and longer contact time conditions. The application of pressure cycles was also found to be beneficial.

Microbial inactivation by High Pressure

Metabolome sampling is one of the most important factors that determine the quality of metabolomics data. The main steps in metabolite sample preparation include quenching and metabolite extraction. Quenching with 60% (v/v) cold methanol at −40 °C has been most commonly used for Saccharomyces cerevisiae, and this method was recently modified as “leakage-free cold methanol quenching” using pure methanol at −40 °C. Boiling ethanol (75%, v/v) and cold pure methanol are the most widely used extraction solvents for S. cerevisiae. In the present study, metabolome sampling protocols, including the above methods, were evaluated by analyzing 110 identified intracellular metabolites of S. cerevisiae using gas chromatography/time-of-flight mass spectrometry. According to our results, fast filtration followed by washing with an appropriate volume of water can minimize the metabolite loss due to cell leakage as well as the contamination by extracellular metabolites. For metabolite extraction, acetonitrile/water mixtur...

Evaluation and optimization of metabolome sample preparation methods for Saccharomyces cerevisiae.

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

To remove caffeine from green tea, supercritical CO 2 (SC-CO 2 ) extraction using 95% (v/v) ethanol as a modifier was carried out on a laboratory scale in the ranges of 150–300 bar and 50–80 °C. The extraction yield of caffeine and catechins including epigallocatechin gallate (EGCG) increased with an increase in temperature at a constant pressure, and also increased with increasing pressure at a fixed temperature. When the CO 2 mass flow rate increased, the total extraction yield of caffeine and catechins also increased, but the extraction efficiency of CO 2 , which was determined by the amount of the solutes extracted per amount of CO 2 used, decreased, possibly due to the negligible effect of external mass transfer resistance around green tea particles and the reduced contact time for SC-CO 2 and green tea. The reduction of green tea particle size by grinding also resulted in the enhanced extraction of caffeine and catechins, which indicates the larger particle size yielded the slower extraction rate. These results gave rise to the conclusion that internal mass transfer resistance is predominant over the external mass transfer resistance in the extraction of green tea by SC-CO 2 like other herbaceous materials. In addition to the extraction of caffeine, the substantial amount of catechins was also found to be extracted during the decaffeination processes.

Effect of mass transfer on the removal of caffeine from green tea by supercritical carbon dioxide

The decaffeination of green tea using supercritical carbon dioxide (SC-CO 2 ) was optimized by response surface methodology (RSM) for the maximal removal of caffeine, and the coextration of chlorophylls was also monitored during decaffeination The experimental conditions for the SC-CO 2 extraction of caffeine were set up according to the Box-Behnken design of RSM The relationships between the extraction yield of caffeine and various parameters used for the SC-CO 2 extraction such as pressure, temperature and concentration of ethanol were studied at a fixed CO 2 flow rate The extraction yields of caffeine and total chlorophyll were significantly influenced by extraction pressure, temperature and concentration of cosolvent, and their extraction yields behaved almost in parallel at different extraction conditions that were obtained by varying pressure, temperature and ethanol cosolvent concentration At the optimal decaffeination conditions such as 30 g of 95% (v/v) ethanol cosolvent per 100 g of CO 2 , 23 MPa, 63 °C and an extraction duration of 120 min for 10 g of green tea leaves, the extraction yields for caffeine and catechins were 9660% (w/w) and 4061% (w/w), respectively, and the substantial coextraction of total chlorophyll (4309% of the total amount) was also observed during the decaffeination process

Hyong Seok Park

Papers

Evaluation and optimization of metabolome sample preparation methods for Saccharomyces cerevisiae.

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

Effect of mass transfer on the removal of caffeine from green tea by supercritical carbon dioxide

Extraction behaviors of caffeine and chlorophylls in supercritical decaffeination of green tea leaves

Addition of ethanol to supercritical carbon dioxide enhances the inactivation of bacterial spores in the biofilm of Bacillus cereus