What differences, practical and aesthetic, are there between egg washes?

Question

An egg wash can be done in six major variations: [with | out egg white] mixed with [water | milk | cream].

My first hit when searching 'egg wash ratio' My Persian Kitchen where the use was for pastries. He advocated a ratio of 1 egg : 1-1.5 tbsp water for the purpose of browning.

He also mentioned the variations above. In my case I will be baking and frying (browning top of loaf in oven, then washing and flouring before frying), however use cases are not restricted to just those two.

• What are the principal differences between washes, and what practical import do the six main ones have?
  • What chemical causes underpin these differences? (e.g. "...the higher ratio of protein to blah, blah...", "water promotes browning more than...")
  • What interactions do these chemical causes have between use on meat, vegetable, pastry, and bread?
• Are there any other special washes/ratios for more particular uses? (i.e. egg white only, egg:vinegar,bourbon,etc)

Answer

Good question @mfg. I hope I can help a little bit. The basics behind the egg wash are to provide for a couple different thing. These being shine, crispness, and color.

Shine The shine is primarily provided by the egg yolk. The higher concentration of yolk the more shine.

Crispness This come from the egg whites. The whites make things a little crispy and sometimes can crackle a little bit (mainly when usually by themselves).

Color This comes from the fat and protein. Leaving the yoke in along with the shine will add color. You can add water to lighten the color a bit. I find that using the white also dilutes the color a bit but not as much (but the white also makes it crisp). Add cream or milk to get it a little bit darker.

Salt I often find people adding salt to an egg wash. I does provide some flavor to the crust, but I have noticed that for some reason (when using a whole egg) it does allow it to get a little darker than it would normally.

Sugar Like salt it adds flavor (sweetness) to the crust. And it will also add some color. Especially if baking at a higher temp and using a raw or brown type sugar.

Alcohol I have seen the use of alcohol quite a number of times. From the results I have seen it behaves like water. Although not the the same degree. My guess is that it has to do with how fast the alcohol evaporates. As far as flavor, I can't say that it added much at the levels used. I did once definitely get a hint of a bourbon being used in the wash on a pretty plain white loaf. But they did mix in quite a good amount of bourbon to just an egg yolk.

That is all I have really used myself or seen. I am sure that you can use other liquids although I don't know what vinegar would do. Just keep in mind if they are high in fat, protein, or sugar they will add color. Otherwise they will lighten the color.

I have also seen melted butter just used as a wash. It adds a nice color and buttery flavor. I haven't seen it added to egg wash but I would assume you could add to egg yolk to get a shine and probably darker color than cream/milk.

Another important thing to remember is to beat your wash well when using for a bread coating. Unlike if your just using the was was to seal say a ravioli. If your egg was is spotty not one nice fully incorporated mixture your crust can also be spotty.

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