Emulsifiers: The Science of Mixing Oil and Water

If you’ve ever tried to mix oil and water, you’ll notice that the two don’t go together. You can stir them into one liquid, but they won’t stay together for long. On an industrial scale, this could be a serious problem for the producers of many of our favorite foods, like cream and bread. This is where emulsifiers come into play. Emulsifiers are substances that bind oil and water together, thus increasing a food’s shelf life. 

In this resource, we will learn what emulsifiers are, the science behind them, and the kind of products that use them. 

Before you can understand emulsifiers, you need to understand emulsion. An emulsion is the mixing of two liquids that normally don’t mix. Picture yourself shaking the bottle of a vinaigrette salad dressing, which consists of oily vinegar and water. The result of this shaking is the two liquids coming together to form an emulsion. Quickly, however, you’ll notice that the two ingredients start to separate again. This is fine for vinaigrettes, but not for other oil-based foods, such as butter or ice cream. To stop separation, food manufacturers use emulsifiers, which prevent water and oil from separating. While this might sound artificial, emulsifiers are completely natural and safe. Emulsifiers come from plants in the form of vegetable oils. For example, sunflower oil is very commonly used for its emulsifying properties. 

To see exactly how emulsification works, we’ll need to go to the molecular level. The reason water and oil do not mix is due to the nature of their molecular structure. Water is a polar molecule, which means that it has a positive charge at one end and a negative charge at the other. Oil is nonpolar, meaning its charge is evenly balanced. Because of this, water molecules will only attract other water molecules, and vice-versa. Emulsifiers have a special molecular structure that bind them to both water and oil molecules. Bound together by the emulsifier, the polar and nonpolar molecules can no longer separate from the emulsion. Next time you eat ice cream, know that you’re eating the results of a complex molecular process. 

Oil-in-water (left) and water-in-oil (right) emulsions

Oil-in-water (left) and water-in-oil (right) emulsions

Should you use an emulsifier? To answer this question, observe the role oil plays in your product. Let’s say that your product is ice cream, which consists mostly of a combination of dairy fat and water. If not for the binding nature of the emulsifiers, your ice cream would split into separate pockets of water and fat. Products that have both high levels of water and oil, such as margarine and pastries, need emulsifiers to stay together. If this sounds like your product, then it might be worth purchasing some at a physical or online retailer. They come in various forms, sizes, and prices. 

In this guide, we went over the process of emulsion, the science behind emulsifiers, and what kind of products use them. Hopefully by now, you have a fair understanding and are able to determine if it might be necessary for your business. For more helpful and interesting guides, check out more of Union Kitchen Resource Guides.

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