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Split or broken mayonnaise is heartbreaker for any home cook, whether it's the first time or the tenth time. However, knowledge is power when it comes to making mayonnaise! And being armed with a simple understanding of physics and chemistry is essential to perfecting the perfect velvety homemade mayo.
Mayonnaise, like ice cream, is an emulsion between oil and a liquid component: either vinegar or lemon. The egg yolk, in addition to giving flavor and density to the sauce, is used as an emulsifier: it's rich in surfactants, molecules with two ends that bind one to the water molecules and the other to those of the oil, functioning like a glue.
With the right amount of oil and vinegar, one yolk is sufficient to emulsify about a liter of mayonnaise, but it's usual to increase the dose to guarantee a more velvety flavour.
Why does mayonnaise curdle or break?
Here's the science bit:
If there's excessive oil in the mix and it isn't whisked in well enough, the mayonnaise splits because the fat molecules are too numerous to distribute evenly among the aqueous ones.
Also, the temperature of the yolks is also fundamental: cold limits the action of the surfactants, therefore you should avoid using cold yolks straight from the refrigerator, and instead use egg yolks at room temperature.
How to Make Fail Safe Mayonnaise?
What you'll need
- A bowl
- Two yolks
- The juice of ½ lemon or two tablespoons of white vinegar
Pour the egg yolks into a bowl and season with salt and a little pepper.
Add the oil drop by drop and mix with the whisk. When the mixture thickens add some of the lemon or vinegar you have set aside and continue alternating oil and lemon (or vinegar) until you have finished them.
Don't overdo it with oil, make sure that none of the ingredients are cold and beat the sauce energetically: the mayonnaise should be thick and shiny.
Watch Jamie Oliver in action:
How to Thicken Homemade Mayonnaise
If you find that your mayonnaise is smooth but more like a thin sauce, simply add more oil, slowly, just a tablespoon at a time and keep whisking. It will thicken naturally as the additional oil disperses through the emulsion.
How to Thin Homemade mayonnaise
Thin with water, add very small drops to begin with and mix in.
How to Recover Broken or Curdled Mayonnaise
It may happen that, despite your best efforts, your mayonnaise curdles or splits into an unappetising mess. Don't despair! Apply a couple of chemistry led techniques to recover your sauce:
1. Whisk in a shot of hot water to the too-liquid compound, to re-establish the right ratio with the oily component and with the surfactants that can now perform their task as best they can, enough to allow the sauce to re-emulsify.
2. Alternatively, you can also add an egg yolk.
Beat an egg yolk in another bowl with a pinch of salt and then add it a bit at a time to curdled mayonnaise while beating constantly until mayo is once again smooth.