Emulsifier as antioxidant in food

Emulsifier as antioxidant in food can play an important role to stabilize the fat or oil in the product against oxidative damage during storage. In oil-in-water emulsion systems (oil-in-water), Oil globules are surrounded by emulsifier molecule membrane so as to prevent the joining of globules. In addition, emulsifier membrane which is as interfacial region (interfacial region) can also act as a barrier to protect oil from oxidation processes induced by transition metals or free radicals.
The mechanism of oxidation of oil in the emulsion system is very different from the oil oxidation in bulk form due to the phenomenon of interfacial layer. The process of oxidation in the system is the oxidation of the interface (interfacial oxidation), which is a reaction that depends on the speed of diffusion of oxygen and its interaction with unsaturated fatty acids, metals and free radicals. So It is a phenomenon of interfaces which is strongly influenced by the properties of the interface itself. An understanding of the interfacial layer to be interesting to explain this phenomenon because of its nature as a physical barrier that alter the interaction between oil and water-soluble prooxidant..
Electric charge on the emulsion layer interface can be modified through the use of anionic surfactants, cationic or nonionic. The difference of electric charge becomes a challenging research because it affects the attraction or electrostatic repulsion of emulsifier to prooxidant and antioxidants which can speed up or slow down the oxidation reaction.
Role of emulsifier as antioxidant in food is also explained as follows. Long polar groups of surfactant and the addition of surfactant above the Micelles Critical Concentration or CMC to form micelles in aqueous phase is expected to hold and dissolve more prooxidant components which approach the interface, thereby increasing the oxidative stability of oil. Although some studies showed that the interface layer electric charge becomes an important factor in the oxidative stability of oil in water emulsion, but only little is known about how the other properties of the interfacial layer effect on the oxidative stability.
Partition behavior of the component effects on its reactivity at oil-in-water emulsion system. Nonpolar antioxidants in the fat globules are more effective in inhibiting oxidation than polar antioxidants which is significantly dissolved into the continuous phase. Emulsions containing surfactant micelles above the CMC produces the continuous phase. Micelles will be able to break and dissolve the antioxidant components or prooxidant approaching fat globules into the water phase of the system so it is expected to provide better oxidative stability. This mechanism is expected to be the new perspective to escort the oxidative stability of oil in water emulsion.
Selection of an appropriate emulsifier such as long-and short polar groups and the concentration of emulsifier used will affect the mechanism of oxidation of oil. Utilization of surfactant micelles to solubilize prooxidant to the water phase can be understood as an antioxidant technology because it can attract ions of transition metals from fat globules into the water phase. This method can provides more effective way to improve the oxidative stability of emulsion-based processed food products. Thus, the role of emulsifier as antioxidant in food is important in addition to its function as an emulsion stabilizer.

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Emulsifier structure

Emulsifier structure allows the activity of the surface (surface-active agents) that lowers the surface tension between the air-liquid and liquid-liquid contained in a food system. Its ability to lower the that tension becomes interesting because they have a miracle chemical structure of compounds capable of uniting two different polarity and at the same polarity protect fats from oxidation because it acts as a barrier (barrier) to metals and free radicals.
The ability of emulsifier structure to lowers the tension because it break the hydrogen bonds at the surface through the withdrawal of the hydrophilic heads on the water surface with a hydrophobic tail extends away. Their tail is hydrophobic which extends into the fat globule, while the head facing the water molecule. So, it gives the hydrophilic coat surrounding globule fat to form an emulsion.
The mechanism of emulsion formation begins with the provision of energy to form a new interface in an emulsion system. At first a liquid dispersed by mechanical means into the liquid to another. The amount of work needed to form globule largely determined by the size of its diameter. Just to mention one example, for dispersing 1 ml of olive oil with a diameter of 5 micrometers in 10 m cubic water needs energy of about 274,800 ergs. However, the amount of this energy will be reduced significantly become only 36,000 ergs when using emulsifiers, because emulsifier structure can reduce tension between the surface of 22.9 dyne / cm to 3 dyne / cm.

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What is emulsifier definition?

Recently, developments in food science and technology are going more rapidly. Processed food products are produced to meet various consumer demands. In several markets, both traditional and at the mall, it is not difficult to find ice cream, sauces, bread with soft texture, mayonnaise, salad dressings, margarine, butter, food, baby formula and other dairy products.
The role of emulsifier
Rapidly development of new food products based emulsions caused by of the dual role of emulsifiers. The phenomenon of a mixture of water and oil tend to be separated can be fused because of "miracle" emulsifier. The compound connector that has two distinct poles, pole of polar and non polar, interacts specifically with the two liquids are not mutually dissolved. Under normal conditions, one liquid dispersed into a liquid that does not dissolve each other. Under abnormal conditions, one liquid dispersed in another liquid as globule whose diameter varies between 0.1 and 100 um. Small scattered globule called discontinuous phase. Meanwhile, the medium of the discontinuous phase is referred to as the continuous phase.
Ability emulsifier lowers the surface tension is a way to break the hydrogen bonds at the surface through the hydrophilic head drawdown at the water surface with a hydrophobic tail stretched away from the water surface.
When oil and water mixture shaken, then it provides the mechanical energy, so that droplets of oil dispersed into water and the emulsion is formed. However, this emulsion system is unstable and soon rejoined the oil droplets. In order for oil or water droplets dispersed in both the long time it takes the presence of an appropriate emulsifier.
The definition of emulsifier
Thus, by definition, emulsifiers is a compound having surface activity (surface-active agents) so as to lower the surface tension (surface tension) between the air-liquid and liquid-liquid contained in a system (in this case is a system of food).
Types of emulsifiers and examples of emulsifiers
Examples of emulsions in food systems include milk, margarine, and ice cream. While in general, emulsifiers consist of a natural emulsifier and artificial emulsifier (synthetic emulsifier). Natural emulsifier made from ingredients derived from nature. Eg from soy beans, egg yolks and so on. In the soybean seed, its oil content are very high, in addition to water. Both are connected by a substance called lecithin. The material is then extracted or taken to be emulsifiers that can be used in processing products.
Actually, lecithin is naturally present also in other grains as well as in animal products, like eggs and brains. But the lecithin that is easy and inexpensive to use is found in soybean seeds.
If lecithin is derived from soy beans, then the terms of the halal will be safer. But it is possible to extract lecithin from other materials, such as eggs and animal brains. In addition to increasing the effectiveness of emulsifying, the lecithin is sometimes added with a specific enzyme. This enzyme also needs to watch out its halal status, because it can come from sources that aren’t considered as halal.
The artificial or synthetic emulsifiers are derived from a human engineering to produce a bridge between oil and water. Although it is called as synthetic, but it is not entirely derived from synthetic materials. Only its manufacturing process are designed man-made, but the materials are often derived from natural ingredients.
Emulsifier in the manufacture of emulsion
The process of making emulsion can be done in various ways, such as by using a homogenizer. In this homogenization process, the liquid will be split into smaller droplets followed by droplet covering process by emulsifiers. If the droplet covering by the emulsifier is so slow then the droplet will be incorporated back (recoalescence) so that the droplets are formed tend to be large in size. So we need a proper selection of emulsifiers for the type of emulsion to be formed.

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