Happy Easter, foodie friends! Our little fam is packing up to hop across town for good family feasting, so re-posting a blog from a while back. About what, you ask? Eggs!
I’ll admit it, I watch Matlock reruns at the gym. Here’s the picture: the bulky dudes lumbering around, dripping sweat as they check out ESPN scores, the fit soccer moms wearing their matchy-matchy spandex while ellipticizing to whichever talk show happens to be airing, and…there I am between them… willing my treadmill to reflect mile-marker 4.0 while watching Andy Griffith solve a murder mystery. Ha! What can I say? I dig a good mystery series. Anyhoo, on Matlock this morning, the killer was a food critic. The weapon? You’ll never guess. An egg, injected with poison! This cracked me up (pun definitely intended) so much, that I schemed a blog post while eating breakfast.
Eggs – they really are incredible. Simple in appearance but mighty in function, the unique culinary properties gained from eggs are unparalleled. From pasteurization, to contamination, to nutrition content…there’s so much sustenance in the science behind eggs. Some of the basics:
Eggs have several components, including the obvious: the shell, yolk, “white” (also known as albumen), and the air cell. These can be observed if you hard boil, and dissect the egg. The not-so-obvious components include: the vitelline membrane (a clear seal that holds the yolk), the chalazae (those small, twisted strands of egg white which center the yolk), thin albumen (the less viscous egg white next to the shell), thick albumen (the thicker part of the white), and two shell membranes (comprised of protein-polysaccharide fibers, which surround the albumen and provide protection from bacterial penetration). See? Not so simple.
Brown or white, the egg shells are mostly calcium carbonate and make up ~10% of the egg, by weight. The shells have thousands of pores which facilitate the exchange of gases; however, proper processing mitigates contamination by way of these porous channels. The entire egg white makes up ~60% of the whole egg, and can be separated into 16-19 different components. (My favorite of these is lysozyme, an enzyme proven to fight gram-positive bacteria which may have entered through the shell.) The egg yolks make up the remaining ~30% of the whole egg and are the predominant source of lipids (fat), vitamins, and minerals. Egg yolks are, of course, yellow but the shade depends on how much carotene was in the feed eaten by the hen. (Some food manufacturers prefer darker yellow shades to give their products a nice yellow hue – think noodles and mayo.)
Most of us keep eggs on hand, because (as we know) applications are nearly limitless. We use the yolks in mayo, custards, batters, and hollandaise sauce because the emulsifying property is unrivaled. We use the whites in meringues, soufflés, and angel food cakes because we know the foaming property adds a stable airiness on which we can rely. And we use a simple egg wash to help baked beauties turn a glossy golden brown, an easy trick which tickles the appeal of any taster.
A Food Science tid-bite: Eggs are a great source of protein, that you know. But, did you know that egg protein is the standard by which other proteins are measured? (I learned this in college, while designing an experiment on the foaming properties of egg protein vs. soy protein isolate…a thrilling read…) Another useful bit of info: after cracking, fresh eggs are identified by a tight, tall yolk, and minimum spread in the white.
Source: Genevieve L. Christen, ed and J. Scott Smith, ed. Food Chemistry: Principles and Applications. Science Technology System, 2000.