Green extraction of microalgae components for incorporation in food and feed supplements (original) (raw)
Related papers
Journal of CO2 Utilization, 2020
Microalgae are a rich source of natural bioactive compounds, e.g. astaxanthin, β-carotene, lutein, and fatty acids (FAs), that are currently in high demand in the market. Conventional extraction methods often produce adverse effects on some of these compounds. Replacing conventional extraction methods with more efficient advanced green technologies that offer greater extracts purity and low environmental impact is therefore a challenging and sought-for target. This review is a comprehensive overview of supercritical fluid (SCF) extraction processes, including the latest research on the extraction of bioactive compounds from microalgae biomass and their benefits on human health. In addition, the role of key operating parameters on the selectivity of various compounds is discussed. This study provides useful knowledge that can productively contribute to the future development of SCF-based extraction technologies on an industrial scale.
Molecules
Supercritical CO2 extraction is a green method that combines economic and environmental benefits. Microalgae, on the other hand, is a biomass in abundance, capable of providing a vast variety of valuable compounds, finding applications in the food industry, cosmetics, pharmaceuticals and biofuels. An extensive study on the existing literature concerning supercritical fluid extraction (SFE) of microalgae has been carried out focusing on carotenoids, chlorophylls, lipids and fatty acids recovery, as well as the bioactivity of the extracts. Moreover, kinetic models used to describe SFE process and experimental design are included. Finally, biomass pretreatment processes applied prior to SFE are mentioned, and other extraction methods used as benchmarks are also presented.
Supercritical carbon dioxide extraction of compounds with pharmaceutical importance from microalgae
Inorg Chim Acta, 2003
Four microalgae (Botryococcus braunii, Chlorella vulgaris, Dunaliella salina, Arthrospira maxima) were object of supercritical CO2 extraction studies, which were carried out in a flow apparatus at temperatures between 313.1 and 333.1 K and pressures up to 35.0 MPa. The microalga Botryococcus braunii produces extracellular alkadienes. Supercritical extracts obtained at 313.1 K, and pressures of 12.5, 20.0 and 30.0 MPa, were golden and limpid, unlike those obtained with organic solvents. The hydrocarbons of this microalga were selectively extracted and this selectivity increased with pressure. The microalga Chlorella vulgaris is a carotenoid producer of canthaxanthin and astaxanthin. The extraction yields of lipids and carotenoids were compared for whole, crushed and slightly crushed algae at a pressure of 35.0 MPa and a temperature of 328.1 K. The yield of supercritical extraction of carotenoids was also compared at several conditions of pressure and temperature. It increased with pressure at constant temperature, remained practically constant with temperature, at pressures of 27.5 and 35.0 MPa, and decreased with temperature at 20.0 MPa. The third alga studied was the Dunaliella salina, which produces β-carotene in high yield. Natural β-carotene (cis and trans mixture) from this alga was submitted to supercritical carbon dioxide and it was assessed, at pressures up to 30.0 MPa and temperature of 313.1 K, that both isomers presented higher solubility than the synthetic trans-β-carotene and that the cis isomer was much more soluble in supercritical CO2 than the trans isomer. Moreover, it was shown that the cis/trans ratio, in the supercritical extracts, increased significantly, relatively to the original one in the microalga, when the Dunaliella was submitted to supercritical CO2. The cyanobacteria Arthrospira (Spirulina) maxima can produce in large amounts the γ-linolenic acid (GLA), C18:3 ω6. The yield and selectivity of the supercritical extraction, using CO2 and CO2 doped with ethanol, of the lipids and GLA were determined and compared with those obtained with organic solvents.Supercritical CO2 extraction studies of compounds with pharmaceutical importance from microalgae are presented. These studies involved the Botryococcus braunii, the Chlorella vulgaris, the Dunaliella salina and the cyanobacteria Arthrospira (Spirulina) maxima, which were used to obtain alkadienes, carotenoids (mainly canthaxanthin and astaxanthin), β-carotene and γ-linolenic acid, respectively.
Antioxidants
Microalgae grow in diverse environments and possess a great biotechnological potential as they contain useful bioactive compounds. These bioactive compounds can be obtained by selective and energy-efficient extraction methods. Various industries are using the supercritical fluid extraction (SFE) method to extract these valuable bioactive compounds. Hence, for the first time, we evaluated the effects of SFE on the recovery of bioactive and antioxidant compounds using Coccomyxa onubensis, a eukaryotic acidophilic microalga of potential relevance which can be used in the field of nutraceutical and functional foods. It was isolated from the Tinto River (Pyritic Belt, Huelva, Spain), a mining region in Spain. Variables such as extraction yield, lutein purity (LP) and recovery (LR), total phenols, and antioxidant capacity (Trolox equivalents antioxidant capacity method) were studied using a Box–Behnken design based on a response surface methodology along with the overall extraction curve ...
Marine Drugs, 2019
This research shows that carbon dioxide supercritical fluid (CO2-SF) is an emerging technology for the extraction of high interest compounds for applications in the manufacturing of pharmaceuticals, nutraceuticals, and cosmetics from microalgae. The purpose of this study is to recover fatty acids (FAs) and, more precisely, eicosapentaenoic acid (EPA) from Nannochloropsis gaditana biomass by CO2-SF extraction. In the paper, the effect of mechanical pre-treatment was evaluated with the aim of increasing FAs recovery. Extraction was performed at a pressure range of 250–550 bars and a CO2 flow rate of 7.24 and 14.48 g/min, while temperature was fixed at 50 or 65 °C. The effect of these parameters on the extraction yield was assessed at each extraction cycle, 20 min each, for a total extraction time of 100 min. Furthermore, the effect of biomass loading on EPA recovery was evaluated. The highest EPA extraction yield, i.e., 11.50 mg/g, corresponding to 27.4% EPA recovery, was obtained at ...
The Journal of Supercritical Fluids, 2014
Supercritical carbon dioxide extraction Microalgae Lyophilization effect Lipid yield and quality Response surface methodology a b s t r a c t Supercritical carbon dioxide (SC-CO 2 ) extraction of lipid from Scenedesmus sp. for biodiesel production was investigated and compared to conventional extraction methods. The effect of biomass pre-treatment prior to extraction and extracting conditions, namely pressure in the range of 200-500 bar, temperatures in the range of 35-65 • C and CO 2 flow rate in the range of 1.38-4.02 g min −1 , on SC-CO 2 extraction yield and quality of lipid were investigated. Three levels full factorial design of experiments and response surface methodology was used to model the system. A second order polynomial model was developed and used to predict the optimum conditions. Scaling up to a laboratory larger scale was also tested. The results indicated that SC-CO 2 extraction was superior to other extraction techniques, but exhibited significant variations in yield with changes in operating parameters. In the developed model, it was found that the linear and quadratic terms of the temperature, as well as the interaction with pressure had a significant effect on lipid yield; whereas, their effect on lipid quality was insignificant. The best operating conditions, in the tested range, were 53 • C, 500 bar and 1.9 g min −1 , in which lipid extraction yield of 7.41% (dry weight basis) was obtained. Negligible differences were observed when the fatty acid composition of SC-CO 2 extracted lipid was compared to that extracted by the conventional methods. At the optimum conditions, SC-CO 2 extraction was successfully scaled-up by eight-folds and the extracted lipid yield dropped by 16%.
Journal of CO2 Utilization, 2020
The microalgae Aurantiochytrium sp. is a strong alternative source of ω-3 fatty acids, including docosahexaenoic acid (DHA). This work encompasses the optimization of SFE conditions to maximize the total extraction yield η () Total , DHA content (C DHA), total phenolics content (TPC), and antioxidant capacity (AOC) of the extracts produced from Aurantiochytrium sp. biomass. A full factorial experimental plan was performed, comprising three factors (pressure, temperature, and flow rate) and two levels (200−300 bar, 40−80°C, and 6-12 − g min 1 , respectively). The maximum and minimum experimental results were = η Total 2.1 and 13.4 wt.%, = C DHA 27.3 and 39.3 wt.%, TPC = 1.19 and 2.24 − mg g GAE extract 1 , and AOC = 0.3 and 1.4 − mg g TEAC extract 1. Under the studied experimental conditions, increasing pressure up to 300 bar is the optimum to rise both η Total and C DHA. Temperature increase from 40 to 80°C leads to opposing effects: it favors the concentration of phenolics in the supercritical extracts at the expenses of decreasing DHA content and total yield. Surface models were adjusted to η Total , C DHA and TPC data, and the goodness of the fits ranged from coefficients of determination of 0.752-0.711 (TPC) to 0.997-0.994 (C DHA). Under optimized conditions, supercritical extracts exhibited a DHA content more than 3.5fold richer than fish oil, and 7.9-fold richer than the best alternative microalgae species (Pavlova lutheri) found in the literature.
Microalgae represent diverse branch of microorganism that can produce a wide range of unique functional ingredients, such as carotenoids, that can be used in food, cosmetics, pharmaceuticals, and energy. Supercritical CO2 (scCO2) emerges as an alternative to organic solvents because of its high selectivity and bioactivity-preserving qualities. Under an industrial point of view, there is an important risk of caking of microalgae such as Haematococcus pluvialis (fine hygroscopic powder) during scCO2 extraction. This results in CO2 channeling through the packed bed, lowering carotenoid's yield. This thesis proposes two alternatives that avoid caking phenomenon of microalgae powders destined for a commercial scCO2 extraction. These alternatives consist in the use High Pressure Compaction (HPC) of the microalgae powder as a pretreatment before scCO2 extraction and direct-extraction of the microalgae paste. To understand the effect of caking in HPC, this thesis developed a simple and easy method to characterize hygroscopic powders by taking advantage of the pressure-induce squeeze flow behavior during compaction. Results showed that this phenomenon was strongly related to the glass transition temperature. This study led to the design of an HPC methodology based on uniaxial compaction of the xii powder in a process similar to tableting. Findings showed that by carefully adjusting the compression pressure and size of the die it is possible fabricate reproducible compacts that have favorable microstructure for the scCO2 extraction of carotenoids. When evaluating the use of direct-extraction of microalgae paste this thesis proposed a scale-down batch-wise extraction system were the microalgae paste is statically placed within the extractor by the use of adsorbents. Water proved to be a strong barrier to the extraction of carotenoids even when using ethanol as a co-solvent. This thesis showed that although both alternatives avoid caking phenomenon, only HPC is an improvement over the powder extraction with promising industrial applications for the production of carotenoids from H. pluvialis.
Extraction of Carotenoids and Fatty Acids from Microalgae Using Supercritical Technology
American Journal of Analytical Chemistry, 2012
The work described here is based on a comparative study of carotenoids and fatty acids extracted from Synechococcus sp. with (1) pure supercritical CO 2 , (2) CO 2 with 5% (v/v) ethanol as cosolvent and ultrasound-assisted extraction using N, N-dimethylformamide (DMF). The effects of extraction conditions on supercritical CO 2 extraction with and within cosolvent were analyzed at different temperatures (40˚C, 50˚C and 60˚C) and pressures (200, 300 and 400 bars). SFE with CO 2 proved to be the most selective method for the extraction of β-carotene, but under these conditions the contents of zeaxanthin and fatty acids were only comparable to or lower than those obtained with techniques that use SFE cosolvent. The SFE technique with CO 2 and ethanol simultaneously extracted β-carotene and zeaxanthin and not only increased the concentrations of fatty acids obtained, but also helped to remove fatty acids (palmitoleic and linolenic acid) that were not obtained with pure CO 2 . Comparison of the supercritical technology with the ultrasound-assisted extraction (UAE) shows that the former technique is the most appropriate due to the fact that ethanol is generally regarded as a safe solvent in comparison to DMF.