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The separation, by addition of a third component, of an aqueous solution of a macromolecule colloid (polymer) into two liquid phases, one of which is colloid-rich (the coacervate) and the other an aqueous solution of the coacervating agent (the equilibrium liquid).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the appearance in a solution of a macromolecular compound of drops enriched in the dissolved material.

Under favorable conditions, the coalescence of the coacervate drops (which may be preceded by flocculation, or their combination to give loose, flaky aggregates) leads to a separation of the system into two liquid layers separated by a clearly defined interface: a layer of the equilibrium liquid, with a low concentration of the macromolecular compound, and a layer of increased concentration, called the coacervate layer. The phase enriched in the polymer (in the form of either droplets or a layer) is called the coacérvate. This term is sometimes applied to the coacervate system as a whole, that is, to the aggregate of the coacervate drops and the equilibrium liquid in contact with the drops.

Coacervation takes place with a change in either the temperature or the composition of the system when the components forming the system lose the capacity to dissolve completely in one another and become only partially intersoluble. This kind of transition is considered the stratification of a single-phase (homogeneous) system into two new phases—the solution of the polymer in the solvent and the solution of the solvent in the polymer. Unlike the stratification of homogeneous mixtures of low-molecular substances (for example, phenol-water or aniline-water systems) near the critical mixing temperature, coacervation is not always reversible.

Coacervate drops and layers exhibit complex structural transformations, arising from the interaction of the macromolecules concentrated therein. The process may occur in two-component and multicomponent solutions of organic and inorganic compounds. The most typical and most thoroughly studied coacervation processes are those in aqueous solutions of proteins and polysaccharides.

The process of coacervation may be either simple or complex. Simple coacervation is the result of the interaction of a dissolved polymer with a low-molecular substance (for example, gelatin with alcohol or sodium sulfate). Complex coacervation occurs through the interaction of two polymers whose macromolecules bear opposite charges (for example, in mixing aqueous solutions of gelatin and gum arabic).

Coacervation may occur in polymer solutions containing a few tenths, or even a few hundredths, of a percent of the polymer, in which case the polymer concentration in the coacervate drops may be as high as several dozen percent. For this reason, coacervation is used as a means of concentrating and fractionating native and denatured biopolymers (in particular, water-soluble proteins) and synthetic polymers. According to A. I. Oparin’s hypothesis of the generation of life on earth, coacervation played an important role in concentrating proteins in isolated areas of the surrounding medium. According to the hypothesis, the combination of the individual hydrated macromolecules into molecular clusters and the subsequent concentration of these clusters into coacervate drops led to the appearance of prebiological systems in the primordial oceans that covered the earth’s surface during remote geological epochs.


Serebrovskaia, K. B. Koatservaty i protoplazma. Moscow, 1971.
Evreinova, T. N. Kontsentrirovanie veshchestv i deistvie fermentov v koatservatakh. Moscow, 1966.
Pasynskii, A. G. Kolloidnaia khimiia. Moscow, 1968. Page 166.
Colloid Science, vol. 2. [Edited by H. R. Kruyt] New York (and elsewhere), 1949. (Article by H. G. Bunoenberg de Jong.)


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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In this context, the aim of this work was to evaluate carotenoid retention of microcapsules produced from pequi oil by the complex coacervation technique.
Caption: Figure 5: Pictorial presentation of complex coacervation technique for protein nanoparticles preparation.
The requirement to balance the viscosity and pH of the coacervation encapsulation process led to the selection of heavy mineral oil as the core material.
It has become a research hotspot of materials science and coacervation physics in physics research and practical application since it was discovered in 2004 due to its excellent physical and chemical properties [3].
Chitosan complex coacervation with WP is composed of by-products from the processing of shrimp, crab (chitosan), and cheese, adding an environmental benefit to the product, as these by-products may be reused and not disposed of in landfill sites or released into rivers by producers [14].
Hyaluronidase could be encapsulated in PLGA using double emulsion technique and coacervation method.
There are many techniques to carry out the microencapsulation of various compounds and microorganisms, among which there may be mentioned spray drying, extrusion, fluidized bed, simple or complex coacervation, liposomes, inclusion in complexes (Gouin, 2004), spray coating, interfacial polymerization, and ionic gelation (Thies, 1996), the latter being a developed process for immobilizing a cell, which uses an anionic polymer mainly alginate as component of the membrane, in combination with divalent ions such as calcium to induce gelation (King, 1988).
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The complex coacervation method is a technique that has been used to produce polymeric microcapsules [4, 5].
These analyses also showed that the polyanionic proteins (i.e., Pc-3 variants) mix poorly with the basic cement proteins (i.e., Pc-1, -2, -4, and -5), invalidating the previous hypothesis of complex coacervation (separation of two oppositely charged polyelectrolytes into two immiscible aequous phases when the charges of the polyelectrolytes are balanced) as a model for the formation of the glue (Wang and Stewart, 2012).
New encapsulation technologies include: spray freezing, fluid bed, pan coating and coacervation. These unique encapsulation technologies provide a targeted release in the gastrointestinal tract, application for rumen bypass and protection for hard to handle active ingredients.