Emulsifying agents are substances that are added to liquid ingredients in order to stabilise the mixture. For example, when oil and water are combined, they will eventually separate into two layers if left to their own devices. An emulsifying agent has stabilising properties that distribute oil and water molecules evenly throughout the mixture to prevent separation. Emulsification is used to make food more visually appealing and to improve taste and texture.
Monoglycerides are a combination of glycerol and fatty acids. According to UnderstandingFoodAdditives.org, monoglycerides are one of the most common types of emulsifying agents. Lecithin, a monoglyceride often found in egg yolks, is frequently used as an emulsifier. Animal fat and vegetable oil can be used to produce artificial emulsifying agents. Emulsifying agents also come in different strengths depending on the size of their molecular structures. An emulsifier with a large molecular size, such as the diacetyl tartaric esters of monoglycerides used in bread, are more potent than those with smaller molecular structures.
Emulsifying agents are able to prevent the separation of oil and water due to their unique molecular structure. One end of the molecule is hydrophilic, or attracted to water. The other end of the molecule is lipophilic, or attracted to oil. Since each end of the molecule is attracted to one of the two main substances in the mixture, emulsifying agents evenly distribute throughout the water and oil rather than forming a separate third layer. The emulsifiers also keep the oil and water evenly distributed, preventing them from forming separate layers of their own.
Some food products are commonly used as emulsifying agents. According to Food Network, milk, eggs, mustard and gelatin can be added to oil and water mixtures to emulsify them. Mixtures can be emulsified by hand by adding an emulsifying agent into a water-based mixture, then slowly pouring in oil while vigorously stirring. The continued motion ensures the emulsifying agent evenly distributes through the mixture to prevent the oil and water from separating. Oil-based salad dressings (such as Caesar dressing) and mayonnaise often require this technique.
Emulsifying agents are one of the most common additives in processed foods. Low-fat margarine spread relies heavily on added emulsifying agents. If the oil were to separate in the spread, it would be susceptible to mould. Emulsifying agents are also used to improve texture in processed baked goods. If oil is not evenly distributed throughout batter or dough, the product will be dense rather than flaky or light. The processed food industry also uses emulsifiers to prevent items from becoming thin or runny over time, such as sauces or dressings.
According to UnderstandingFoodAdditives.org, emulsifying agents are used in a large array of foods. Although baked goods, mayonnaise and margarine tend to rely most heavily on emulsifiers, they are also used to extend the shelf life of breakfast cereals and dehydrated potato flakes. Emulsifying agents are added to soft drinks to prevent separation of the sugars and other materials. They also help toffee, caramel and chewing gum retain their textures.