Egg yolk contains, amongst other things, a material called “lecithin”, which is an emulsifying agent, like soap. Lecithin molecules have one end that is water soluble (“hydrophilic” in chemistry lingo) and another end that is oil soluble (“hydrophobic). When egg yolk is mixed with oil and water and stirred or beaten vigorously, the lecithin literally sticks its hydrophilic end in the water droplets, making a sphere of lecithin spikes sticking out of the small water droplets. The ends sticking out are hydrophobic, and dissolve in the oil. (It would work the other way, but due to how mayonnaise is made, it the water that gets the lecithin first). These aggregates of water and lecithin are called “micelles” and essentially hide the water in an oil soluble material.

Soap does exactly the same thing, because it has a hydrophobic and a hydrophilic end, as do synthetic detergents. That is why grease and oil can be washed away using soap. According to evolutionary biology, these simple micelles are the precursor to the modern cell membrane, with is essentially a double layer of micelles, that is, a micelle within a micelle.

With mayonnaise, vinegar and/or lemon juice is added, along with salt, for flavor. Commercial mayonnaise often contains a sweetener and some proprietary spices, along with a preservative, usually calcium disodium ethylenediaminetetraacetic acid (EDTA). EDTA is not really that bad for you, and is used as a drug to remove excess calcium in a condition called hypercalcemia (the tetrasodium one is used for that) or the remove certain heavy metals in cases of poisoning. In mayonnaise, it combines (“chelates”) with iron and other metals that would tend to make the mayonnaise separate and tend to go rancid quickly, since the mayonnaise on the store shelf sits there for some time, and in your refrigerator for a long time after you open it.

It is easy to make mayonnaise at home, and I recommend it IF you can find a source of eggs for which you can be reasonably certain are not contaminated with salmonella. Commercial mayonnaise is pasteurized, so that is not a risk. If you can assure a supply of safe eggs, here is a simple and fast recipe. It makes a pint. I do not recommend making more since there are no preservatives. It is so quick to make that even if you run out, you are only a couple of minutes away from fresh.

Basic Mayonnaise

1 large egg

2 tablespoons lemon juice or vinegar (I like half and half)

1/2 teaspoon salt, or to taste

1 tablespoon prepared yellow mustard

1 3/4 cup vegetable oil (use a bland one, like soy)

While you can make mayonnaise by hand, now and then a batch will fail, and it takes quite a while and a whole lot of whisking. Place everything except the oil in a blender or food processor, and process for a few seconds.

Add a couple of tablespoons of oil and process until the mixture is homogeneous (I am not talking about da Vinci)

While processing continuously, slowly add a thin stream of oil such that it is all taken up as it is added. If you see any separation, stop adding oil and process until the mixture is homogeneous again, then resume adding oil. After about half of the oil has been added, you will notice the mixture beginning to thicken. Here is where a food processor is a little better than a blender because the geometry of the processor is better for thick mixtures. If the blender is not mixing completely, stop and use a rubber spatula to mix, then continue adding oil.

You want to work quickly to keep from heating the mayonnaise up any more than possible. After the oil has all been blended in, put the product in a clean glass Mason jar, cap, and refrigerate. It will keep until you use it up if you keep it cold.

It has taken longer to describe how to make mayonnaise than it does to make it.

Variations:

After finishing the mayonnaise, you can blend in prepared horseradish to taste. Excellent with beef, hot or cold.

You can add extra mustard, either yellow, Poupon, or hot Chinese.

For a novel red appearance, you can puree a cooked beet or two with the initial ingredients before the oil is added. Reduce oil by one tablespoon for each beet.

For a novel green appearance, you can do the same with some freshly cooked spinach or spinach cooking water.

If you want yellow mayonnaise, add some turmeric before the oil.

My personal preference is not to add any sweetener to mayonnaise, but you may prefer a little sugar in it, or some Karo. I like it plain, but I also prefer vanilla ice cream. Any experiences with variations on this recipe are welcome, as are other comments or criticisms. Warmest regards, Doc.

Update: Here is a sketch of a micelle.