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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