What is the function of eggs in pastry
Eggs are an indispensable ingredient when making pastry. Eggs provide richness, color, structure and tenderness to the final product. Whole eggs contain the egg yolk (protein part of the egg) and egg white, also called albumen). The egg yolk contains lecithin which is an emulsifier (ability to combine two liquids that are unblendable, for example fat and water).
Here are some characteristics of eggs;
- Egg yolks and egg whites are leavening agents because when beaten they incorporate air into the mixture.
- Eggs are used as thickening agents for creams and cakes.
- Egg yolks work as emulsifiers when making cakes.
- Eggs add color or shine to the final product.
- Egg whites contribute a clear shine to the finished baked product.
- Egg whites are full of protein, which creates a water-resistant coating when pre-baking pie shells (blind baked)
- Egg yolks contribute a golden color to the finished baked product.
Other useful information about eggs
The danger zone for pathogens (microorganisms that cause disease, eg; viruses) is between 4 – 60 deg C. Pathogens are destroyed or growth slowed down at temperatures above 60 deg C, and below 4 deg C. Therefore eggs should be stored in the refrigerator that maintains a temperature around 3-4 deg. C.
Temperature conversion formula
Given a temperature in Celsius; (Celsius x 1.8) + 32 = Fahrenheit
Given a temperature in Fahrenheit; (Fahrenheit - 32) / 1.8 = Celcius
How much water is the equivalent of one egg?
Lets make a few assumptions about an egg.
If a large egg yolk weights 20g and a large egg white weights 35g (whole egg = 55g) and if each egg yolk contains 50% water and 50% solids (lecithin and fat) and if each egg white contain 90% water and 10% protein, then, for every egg that you add in a recipe you would have to remove 41.5g of water.
Here's the calculation. If the percentages are correct here's how you would come up with 41.5g. Each egg yolk is the equivalent of 10g of water (20g per egg yolk x 50% = 10g water) and each egg white has the equivalent of 31.5g of water (35g x 90%). Therefore a whole egg is the equivalent of 41.5g of water.
1 whole egg can also be replaced by flax seeds or gelatin;
1 tbsp flaxseed, ground + 3 tbsp water
1 tbsp unflavoured gelatin + 3tbsp water
How to get the most volume out of your egg whites
Using egg whites you can make French, Italian and Swiss meringues. To get the greatest volume in eggs, make sure they are at room temperature prior to beating them. If you have a recipe that requires egg whites, remove the eggs (with the shell) from the fridge and place them in fairly warm water (~ 52 deg. C) for a couple of minutes. Once warmed, crack the eggs and separate them. Make sure that not even one spec of egg yolk has fallen into the egg whites or you will not get the maximum volume.
When to use pasteurized eggs
Commercial egg products sold in cartons are safe because these have been pasteurized in order to destroy harmful salmonella bacteria. Pasteurized egg whites sold in cartons should be used when the final product will be consumed uncooked, as French meringue cookies. Pasteurized egg yolks sold in cartons contain sugar to keep them from separating. Pasteurized egg yolks do not usually cause any problems in recipes but when making meriingues, the pasteurized egg whites sometimes do cause problems, for example cannot be whipped to stiff peak, but remain watery. You will see in our online pastry training videos how to deal with such a problem.
How does one know if an egg is fresh
Dip the egg(s) in a pot of room temperature water. If the egg floats the egg is old. If the egg sinks down to the bottom it is fresh.
For a lot more detailed information on eggs please follow this link.