Why have chocolate eggs when you can have raw eggs?

Are you all tired of waiting a full year just to get that small week-long window in March (because grocery stores love to setup a month in advance) to purchase some mini chocolate eggs? Well, I am, and I also have the perfect solution for you all! An extremely common item that I’m sure that many of you have in your fridge right now, real eggs! This year, treat yourself by indulging in some raw eggs (cooked if you want, I guess, yuck!).

Honestly, this Easter blog was between chocolate eggs and real eggs. Unfortunately, chocolate as a matrix is a little complicated, so let’s look at regular eggs! Specifically, we’re going to look at cholesterol in the egg yolk. This idea hit me as I was taking my daily dose of raw eggs, when I thought, “why not try and analyze this to see what I am putting in my body?”. It started out with separating the yolk from the albumen, more commonly known as the egg white, and obtaining the ¹H nuclear magnetic resonance (NMR) spectrum of those in our 60 MHz benchtop spectrometer in chloroform-d. Unfortunately, I did not see too much in the egg white, but the egg yolk looked a little more promising and its ¹H NMR spectrum is shown in Figure 1.

Figure 1. ¹H (60.7 MHz) NMR spectrum of raw egg yolk in chloroform-d.

The component of this spectrum that caught my eye was the multiplet centered at 5.35 ppm, as this peak is characteristic of the proton of the double bond in a cholesterol sample I had previously collected. So, I decided to investigate this a little further and that meant trying to eliminate the broad signal at 4.61 ppm. To do this, I researched some extraction methods and ended up finding and following a procedure outlined by Nix et al.¹ Upon obtaining the extract from the egg yolk, I obtained a ¹H NMR spectrum of a cleaner product and doped it with some pure cholesterol, which is shown in Figure 2.

Figure 2. ¹H (60.7 MHz) NMR spectrum of egg yolk extract with the proton of interest highlighted in red and a stacked inset showing an increase in this signal’s intensity upon doping with pure cholesterol. The stacked inset shows the ¹H (60.7 MHz) NMR spectra of pure egg yolk (green trace), egg yolk spiked with 20 mg cholesterol (red trace) and egg yolk spiked with 60 mg cholesterol (blue trace). The residual solvent signal for chloroform was used to normalize the stacked plots.

The stacked spectrum here shows that as we dope the initial sample with more pure cholesterol, the characteristic peak centered at 5.35 ppm also begins to grow, which suggests that we did indeed separate cholesterol from the egg yolk in addition to other potentially chloroform-soluble compounds.

With that being said, I think I’m a little bit sick of eggs now, but if you ever have any questions with eggs or anything, please don’t hesitate to contact us! That’s all from me this month, so have a wonderful Easter and enjoy our Easter video!

[1] Washburn, K.W.; Nix, D.F. Poult. Sci. 1974, 53, 1118-1122.