The Principles Of Emulsification

Let's start by explaining what an emulsification is and how it relates to cooking. An emulsification is a mixture of two or more liquids that normally wouldn't mix. Think oil and water. This is done through the use of a binder or an emulsifier. In cooking, this could be mustard in any form or egg yolk.

Common items that are emulsifications include any well-made salad dressing, mayonnaise, hollandaise sauce, hot dogs, chocolate, homogenized milk, and butter. All of these items contain at least two substances that don't mix naturally. They are held together with either an added stabilizer or by a stabilizing process.

I find that emulsifications are a pretty good place to start when teaching cooking. The concept of an emulsion is pretty complex and even explaining the process at times can be difficult. However, the actual application of the emulsion technique, when simplified to it's most basic processes, is much less daunting than one might expect.

Let's look at the process of how to build a simple vinaigrette.

A vinaigrette is an emulsion of oil and vinegar. This is generally accomplished with the use of mustard as the binder. It is actually a protein or string of proteins in the mustard called lecithin, not the mustard itself that binds the two liquids. This same string of proteins is found in egg yolks and soybeans. So you have oil, vinegar, and lecithin in a bowl but the emulsion breaks. What happened?

If you have ever made a salad dressing or otherwise mixed oil and vinegar it is likely that the two liquids have separated. If looked at it through a glass jar you would be able to see the oil floating on top of the vinegar or water. This is a separation of the two liquids. In terms of an emulsification, we refer to this as breaking or spitting. When an emulsion is properly formed it will hold together for a very a long time.

There are two main things to think about when building an oil and vinegar emulsification.

Number 1. The ratio of oil to vinegar.

Generally, for a basic vinaigrette, a ratio of 3 parts oil to 1 part vinegar will create a nice texture and a slight tartness. For a thicker vinaigrette, a ratio of 4 parts oil to 1 part vinegar can be made. The extra oil causes a thicker dressing, which may seem counterintuitive. But because more oil droplets are suspended and dispersed throughout the vinegar the dressing gets a thicker creamier texture.

Imagine a room ¾ full of coloured plastic balls. This room illustrates a standard 3:1 ratio. It's a lot of balls. It is difficult to move around but not impossible. Now imagine the same room but so full of plastic balls that you couldn't fit one more in. It would be much more difficult, if not impossible to move around. This second example illustrates a 4:1 ratio. The more oil you add the thicker the dressing will get. Does that make sense?

Number 2. The process of making the emulsion.

A strong emulsion is one that is made slowly.

Imagine the room from the above example. If you tried to fill the room with all the plastic balls at once it wouldn't work. You would never be able to get them all through the door. You have to fill the room with a few plastic balls at a time. The same principle is true of building an emulsification.

The first step in the process is to mix the vinegar with the binder. Imagining that we want about 1 cup of vinaigrette we would mix ¼ of vinegar with 1 teaspoon of mustard powder. The next step is to take our ¾ cup oil and mix it into the vinegar and mustard. But, as we know from the plastic ball in the room example we can't just pour all of the oil in and build a stable emulsification. We have to start slowly.

While whisking, we pour a few drops of oil in the vinegar and mustard mixture. We whisk until the oil has been fully incorporated into the vinegar. We know this has happened because there are no visible sheen or oil droplets. Once this first amount of oil is emulsified we add a bit more oil. We continue this process until all of the oil has been incorporated.

Other Emulsifications

The above process is pretty much the same for any type of emulsion. Let's look at mayonnaise.

In mayonnaise, the emulsion is bound by lecithin in the egg yolk. As a back up there is often a bit of mustard added as well though this is mostly unnecessary. For the mayonnaise, we are going to use a ratio of 1:1 for the egg to oil and 4:1 for the oil to vinegar. This is 1 egg yolk, 1 cup of oil, and ¼ cup of acid which may be just vinegar, just lemon juice, or a combination of the two.

Just like with the vinaigrette we start by mixing the egg yolk (the binder) with the vinegar or acid. From there we slowly start to whisk in the oil a few drops at a time.

The process is exactly the same for hollandaise sauce except the egg yolks are tempered with the vinegar (heated but not to the point of cooking) and clarified butter is used rather than oil.

Conclusion

Like I said in the opening, the process of making an emulsion is less complicated than the theory behind it. It is not the easiest thing in the world to do or master but it is not the most difficult either. Learn this one technique and you can make any kind of salad dressing you can imagine, homemade mayo, and of course the most decadent of all the sauces, hollandaise.