Cold Solvent |
Does not degrade the target substance. Simple and low-cost process. |
Delayed process, which favors incomplete extraction. Another problem is the likelihood of contamination by using solvents containing large amounts of water. |
Melecchi et al. (2002Melecchi MIS, Caramão EB, Nascimento Filho I, Abad FC, Zini PP & Martinez MM (2002) Chemical Composition of Hibiscus tiliaceus L. flowers: A Study of Extraction Methods. Journal of separation Science, 25:86-90.); Miranda & Cuéllar (2001Miranda M & Cuéllar A (2001) Farmacognosia y Products Naturales. Havana, Editorial Felipe Varela. 437p.) |
Soxhlet |
Extraction of high efficiency, with the sample always in contact with the solvent, having its constant renewal. A simple process that requires no filtration after the extraction is finished. |
It can promote the partial degradation of thermolabile compounds, as well as the high consumption of water and energy. |
Bimakr et al. (2012Bimakr M, Rahman A, Taip S, Adzahan M, Sarker M, Islam Z & Ganjloo A (2012) Optimization of ultrasound-assisted extraction of crude oil from winter melon (Benincasa hispida) seed using response surface methodology and evaluation of its antioxidant activity, total phenolic content and fatty acid composition. Molecules, 17:11748-11762.); Fellows (2009Fellows J (2009) Food processing technology: Principles and Practice. 3ª ed. Cambridge, Woodhead Publishing Ltda. 912p. ) |
Ultrasound assisted |
Reducing the time and volume of chemical solvents, being a simple and effective process. |
Possible damage can be caused by free radicals. |
Jarvis & Morgan (1997Jarvis P & Morgan D (1997) Isolation of plant products by supercritical-fluid extraction. In: Jarvis AP & Morgan ED (Eds.) Phytochemical Analysis: An International Journal of Plant Chemical and Biochemical Techniques, 8:217-222.); Herrero et al. (2006Herrero M, Cifuentes A & Ibañez E (2006) Sub-and supercritical fluid extraction of funtional ingredientes from different natural sources: plants, food-byproducts, algae and microalgae. Food Chemistry, 98:136-148.) |
Supercritical fluid |
Use of low temperatures, and can be used for thermally sensitive analytes. Other advantages are the low energy consumption, low levels of degradation of chemical compounds. In this technique, operational changes during extraction are allowed, facilitating the recovery of specific compounds. In addition, the most commonly used solvent is carbon dioxide (CO2), which is inert, non-flammable and does not harm the environment. |
Carbon dioxide (CO2) is apolar in nature, which, having four non-ligand pairs of electrons, is able to dissolve weakly polar substances or with some polarity at pressures greater than 250 bar but does not dissolve high molecular weight compounds such as amino acids, proteins, sugars, polysaccharides, inorganic salts and flavonoids. Considering the use of high pressures, expensive equipment is required, increasing the cost of the final product. |
Reverchon & De Marco (2006Reverchon E & De Marco I (2006) Supercritical fluid extraction and fractionation of natural matter. The Journal of Supercritical Fluids , 38:146-166.) |
Pressurized fluid |
Allows for the fast extraction and reduction of solvent consumption. Therefore, inert solvents such as ethanol and water, which are used in the extraction of some phenolic compounds at low temperatures, can be very efficient at high temperatures applied in the extraction with pressurized fluid. |
Higher operating cost |
Santos et al. (2012Santos T, Veggi C & Meireles A (2012) Optimization and economic evaluation of pressurized liquid extraction of phenolic compounds from jabuticaba skins. Journal of Food Engineering, 108:444-452.) |
Microwave-assisted |
This technique meets the requirements of the perspective of green chemistry, because it uses less solvent, low extraction cost with increased production and has as main advantage the reduction of extraction time. The reduced extraction time is attributed to the difference between conventional heating and microwave heating. |
Not applicable |
Wang et al. (2005Wang X, Saridara C & Mitra S (2005) Microfluidic supported liquid membrane extraction. Analytica Chimica Acta , 543:92-98.) |
Microfluidic system (microchannels) |
One of the major differences between microchannels and large-scale devices is the increased surface/volume ratio. Accordingly, miniaturization can be an effective way of increasing heat and mass transfer rate. This type of process can reduce the volume of solvents, process time and the cost of mass production. |
They may present physical effects such as capillarity and surface tension, and therefore require a more complex form of system modeling. Microfabrication techniques still require cost reductions and the development of new materials supplying applications in the most diverse areas. |
Wang et al. (2005Wang X, Saridara C & Mitra S (2005) Microfluidic supported liquid membrane extraction. Analytica Chimica Acta , 543:92-98.); Faryadi et al. (2014Faryadi M, Rahimi M, Safari S & Moradi N (2014) Effect of high frequency ultrasound on micromixing efficiency in microchannels. Chemical Engineering and Processing: Process Intensification, 77:13-21. ) |
Membranes |
They provide high quality phenolic compound concentration considering the low operating temperature, in addition to providing low energy consumption. |
When the solution to be filtered contains solutes that can not pass through the membrane occurs fouling due to the accumulation of retained solutes, which provides additional resistance to mass transfer. Constant removal of these solutes from the surface of the membrane is required. |
Cassano et al. (2013Cassano A, Conidi C, Giorno L & Drioli E (2013) Fractionation of olive mill wastewaters by membrane separation techniques. Journal of hazardous materials, 248:185-193.); Kim et al. (2015Kim K, Jung Y, Kwon H & Yang W (2015) Dynamic microfiltration with a perforated disk for effective harvesting of microalgae. Journal of Membrane Science, 475:252-258. ) |