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Emulsification is the process of forming an oil–water emulsion by dispersing a lipid in a polymer solution in the presence of surfactants, and it is used to make cosmetic products. These techniques have been applied, for example, to the preparation of chitosan nanocapsules containing concentrated unsaturated fatty acid concentrations.
Emulsification Method
It is the process by which the dispersed phase is broken up into small droplets that is referred to as emulsification. Normally, a coarse premix is produced by vigorously mixing the elements together. In order to allow for adsorption of the emulsifiers prior to the final emulsion, it is necessary to break up the dispersed phase into big droplets before the final emulsion. Mechanical homogenization (e.g., rotor–stator) and high-pressure homogenization are the two main methods/principles that are routinely employed in the food business to homogenise emulsions. (Walstra, 1983; Robins and Wilde, 2003; Robins and Wilde, 2003). Droplets are broken apart using mechanical processes that generate large shear fields. With the widespread use of high-pressure homogenizers in recent years, it is no longer necessary to drive the premix through a tight orifice or valve under high pressure (usually 10–100 MPa). When you force an emulsion through a valve at high pressure, it creates turbulence and extremely strong shear pressures, which causes the droplets to break up. When it comes to breaking up droplets, shear forces are not the most efficient method because the shear field tends to lose energy while spinning the droplet. When droplets are forced through a small orifice, elongational flow forces are created, which aid in the breakdown of droplets more efficiently. When operating within specified parameters, the size of the droplets formed is often inversely proportional to the amount of energy used during homogenization. More precisely, it is the energy that is wasted as a result of droplet break-up. This is influenced by the interfacial tension, which has been discussed previously, as well as the viscosities of the dispersed and continuous phases, among other factors. Droplet size decreases as the continuous phase viscosity increases; but, when the dispersed phase viscosity increases, the droplets become more difficult to break apart, and droplet size increases as a result (Walstra, 1993).
This technique, which is the most energy efficient of the homogenization methods, is also attracting more interest. Crossflow membrane emulsification is another type of homogenization that is receiving increased attention (XME). It is necessary to drive the dispersed phase, or a premix, through a porous substrate in order to reach the continuous phase (Charcosset and Fessi, 2005). The size of the droplets formed is determined by the interfacial tension and the size of the pores. Because of the poor throughput of these microporous technologies, they are still in the early stages of development and have not yet been widely adopted in the food business.
Surface Tension Theory: In accordance with this idea, emulsification occurs as a result of a reduction in the interfacial tension between two phases of a solution.
Repulsion Theory: The notion of repulsion states that the emulsifying agent produces a film over one phase, resulting in the formation of globules that repel one another. As a result of this repulsive force, they are able to remain suspended in the dispersion medium.
Viscosity Modification: Acacia and tragacanth, which are hydrocolloids, as well as PEG (polyethylene glycol), glycerine, and other polymers such as CMC (carboxymethyl cellulose), all increase the viscosity of the medium, which aids in the formation and maintenance of the suspension of globules of dispersed phase.
Emulsification uses
In Food
Oil-in-water emulsions are commonly seen in a variety of culinary products.
Mayonnaise and Hollandaise sauces are oil-in-water emulsions that are stabilised by egg yolk lecithin or other forms of food additives, such as sodium stearoyl lactylate. Crema (foam) in espresso – coffee oil in water (brewed coffee), unstable colloid
The term “homogenised milk” refers to an emulsion of milk fat in water that contains milk proteins as an emulsifier.
In the preparation of vinaigrette, which is an emulsion of vegetable oil in vinegar, if the oil and vinegar are used alone (i.e., without an emulsifier), an unstable emulsion is produced.
Despite the fact that emulsions of water and oil are less common in food, they do exist:
Butter is an emulsion of water and butterfat that is used to make margarine.
Margarine
Other foods can be transformed into products that are similar to emulsions, for example, beef emulsion, which is a suspension of meat in a liquid that is similar to true emulsions, can be made.
In Health Care
Emulsions are extensively utilized in a variety of industries, including pharmaceutics, hairstyling, personal hygiene, and cosmetics. These are often oil and water emulsions that have been dispersed, and whether they are continuous or discontinuous depends on the pharmaceutical formulation in many situations. These emulsions are classified as creams, ointments, liniments (balms), pastes, films, or liquids, depending on their oil-to-water ratios, other additives, and the method of administration by which they are meant to be applied. The first five are topical dose forms that can be applied to the skin’s surface, transdermally, ophthalmoscopically, rectally, or vaginally, depending on the formulation. In some circumstances, a highly liquid emulsion can be taken orally, while in others, it can be injected.
In firefighting
The use of emulsifying agents is efficient in putting out fires caused by minor, thin-layer spills of flammable liquids (class B fires). This type of agent encapsulates the fuel in a fuel-water emulsion, where the combustible vapours are trapped within the water phase. Using a high-pressure nozzle, it is possible to create this emulsion by introducing an aqueous surfactant solution into the fuel. Due to the fact that the amount of emulsifier agent required for extinguishment is proportional to the volume of the fuel, emulsifiers are ineffective in extinguishing large fires involving bulk or deep liquid fuels. In contrast, other agents such as aqueous film-forming foam require only a thin layer of coverage over the surface of the fuel to achieve vapour mitigation.
Chemical Synthesis
When it comes to polymer dispersions, emulsions are employed to make them. Producing polymers in an emulsion “phase” has a number of advantages over other processes, including the prevention of product coagulation. It is possible to employ the emulsions created by such polymerizations as the major components for glues and paints, as well as for other applications. This procedure also results in the production of synthetic latexes (rubbers).
Conclusion
Therefore, we can finally conclude in this topic that different processes, such as diffusion or coacervation, can be used in conjunction with emulsification. The first step in all of these processes involves emulsifying the wall material solution containing the substance to be encapsulated, and the second step is similar to the first step in emulsification. In the process of spreading two or more immiscible liquids together to form a semistable mixture, the term “emulsification” is used. In food applications, these two liquids are typically divided into two phases: an organic (oil) phase and an aqueous (water) phase that is stabilised by the inclusion of a food-grade emulsifier (emulsifying agent) (surfactant).
