The many faces of eggs

This week, we focused on eggs and emulsion. So, the discussion returned to the topic of proteins. A couple of weeks ago when we examined enzymatic browning, we focused on protein structure, function, and enzymatic activity. This week, in addition to these topics, we talked more about the chemical properties of proteins. Proteins have the abilities to coagulate, emulsify, turn into foams, and high water solubility. This versatility makes eggs an important ingredient in cooking and baking. In eggs, almost all of proteins are in the egg white while the lipids are in the yolk and an interesting fact I learned is that in egg yolk, there is lecithin, which is a good emulsifier (Emulsification is mixing of two or more liquids that are normally insoluble in each other by having one liquid disposed in the other).

Using this knowledge, we made French style meringue and mayonnaise! We made one version of meringues using regular sugar, and another with superfine sugar. The proteins in meringue had to be denatured so that the the peptide bonds could uncoil into long strands. The cream of tartar that is usually included in the procedures for making meringue could be substituted with a drop of vinegar because the purpose was simply to acidify the proteins in the eggs. If heating makes proteins denature without breaking the primary structure, lowering pH has the same effect by making the proteins much less charged and disrupting the salt bridges and hydrogen bonds. The uncoiled amino acids join together and are able to coalesce. After the egg whites foam from constant beating, the bubbles created by the foam allow sugar to dissolve into proteins, making the meringue swell up.

I liked the taste of the meringues made with regular sugar since the one made with superfine sugar gave a little bit of artificial taste, but both were just fine for some sugary dessert. For mayonnaise, it was surprisingly easy to make it but it did require a lot of arm exercise to whisk it continuously to prevent adding air into the mixture.

Eggs seem like a fun, yet complex food topic, which is why Annie and I are working with eggs on our second project. We’re excited to find out more about the various transformations of eggs and their high nutritional values!