I have discovered century eggs while living in Thailand, and instantly fell in love with these treats. Unfortunately, I haven't lived in Thailand for a few years now, and I desperately miss century eggs. It's impossible to purchase them anywhere within 1000 km radius, so I guess the only option is to make them myself.
So, I need an advice, how can I recreate this mesmerizing gift of Asian cuisine?
What have I tried so far — I have followed this recipe on Instructables, which in short was:
- Made brine by combining 42g NaOH + 72g NaCL + 1L water, boiled, dissolved and let it cool down. I have used pipe drain cleaner (100% NaOH).
- Carefully put four chicken eggs in a glass jar, poured brine until eggs became fully submerged.
- Put a small glass weight on top to prevent eggs from floating.
- Kept them in brine for 10 days at approx 18°C.
- Removed eggs from brine. Found two eggs to crack, with only disfigured yolk remaining inside.
- Thoroughly washed two remaining intact eggs with tap water, then dried them up completely with paper towels.
- Tightly wrapped eggs in few layers of clear thin plastic wrap, then covered them in modeling clay shell.
- Kept them for 20 days this way.
After time was up, I opened them, to find out to my own disappointment that my experiment had failed. The eggs were filled with a foul-smelling opalescent runny fluid about the density and viscosity of water, and the eggs themselves had shrunk away to the size of the yolk. The egg whites had stayed white, dense and opaque, and only a thin layer of it was left around the yolk. The yolks themselves were still yellow with a slight blue tint, and had overall texture of hard-boiled yolk.
Obviously, this was not the result I wanted, so I threw them away without tasting 🙁
Since then I have done a few more attempts, still with no luck. I have even discovered scientific papers on this matter, e.g. "Effects of alkaline concentration, temperature, and additives on the strength of alkaline-induced egg white gel.", Zhao Yan et al, doi: 10.3382/ps.2013-03596, however I was somewhat hesitant about experimenting on myself, as the paper gave no conclusions whether the provided metal salt concentrations are safe for human health with prolonged consumption.
So, can anyone point out any mistakes I've made during my attempts, or provide me with the right technique to make Century Eggs that I can follow? It is surprisingly difficult to find English recipes for these on the Internet.
Best Answer
What I think you have made is brined or salted eggs which are very different from the blackened "century" eggs.
Salt preserved eggs do need cooking, at least the egg white will need heat to solidify. If you extract an egg yolk and cure that with salt and sugar (no added water), you can use it almost like cheese, the texture would allow you to grate it over pasta without cooking for example.
The blackened century eggs do not require cooking, because it is already cooked, or the proteins fully denatured. It takes alkalines and salt to achieve that. The high pH usually comes from a combination of lime (calcium oxide) and calcium hydroxide. The process is very different. Strangely, you get the opposite of brining when it comes to textures - solid "white" and runny yolk vs runny white and somewhat hardened yolk.