How to Make Century Eggs

Century Eggs

 

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 Safety Measures

  • Sodium hydroxide can burn your skin and flesh. Wear protective gloves.
  • Sodium hydroxide reacts violently when it comes in contact with water. It can spatter and froth. For this reason, you want to add it to a pot filled with liquid, not the other way around.
  • Sodium hydroxide is highly corrosive. Do not use metal vessels or utensils for making century eggs (except high-grade stainless steel, see the section below on containers). It will also corrode glass and destroy certain types of plastic.
  • Sodium hydroxide is safe to pour down the drain once your eggs are done.
  • Sodium hydroxide is not flammable or combustible.

Concerning Containers

Since sodium hydroxide is highly corrosive, you do not want it to come in contact with metals. It will also corrode glass over long periods of time, so mason jars are also out of the question.

High-quality (“food grade” or “surgical grade”) stainless steel is safe for storing sodium hydroxide. Look for the numbers 18 / 8 or 18 /10, which refer to the percentage of chromium and nickel in the steel, respectively. These are also referred to as Type 304, part of the 300 series. Lower grades of stainless steel (in the 200 series) are safe for most food storage, but they contain manganese instead of nickel and are therefore less resistant to corrosion. Avoid these for this recipe.

Certain plastics are reportedly safe for storing lye, while others are not. I have heard that polypropylene (PP, SPI code 5) and high-density polyethylene (HDPE, SPI code 2) are the safest options. Definitely avoid the ubiquitous polyethylene terephthalate (PET/PETE, SPI code 1). The lye will eat through it in no time.

I did not feel comfortable with using plastic at all for such a long exposure, so I went for a large stainless steel saucepan marked 18/8 instead.

 Century Eggs

Materials and Equipment

  • Scale
  • Food-grade sodium hydroxide (I bought this one)
  • Large high-grade stainless steel pot with lid (see section above on containers)
  • Eggcups, or something to hold the egg upright as the wax dries
  • Beeswax (I like to buy beeswax pellets, because they are easier to measure out and melt)

This recipe has two parts. In the first part, we soak the duck eggs in a solution of sodium hydroxide, salt, and tea until the proteins in the egg white have denatured, forming a dark-coloured gel. In the second part, we seal the pores of the eggshell using beeswax, to protect the egg from pathogens and from oxidation. The whole process takes about 6 weeks, also only three of those days involve any actual work.

 

Yields 12 Century eggs

Serves 12

How to Make Century Eggs (皮蛋)

Step-by-step instructions on how to make the delicious Chinese delicacy pidan (皮蛋) at home.

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Ingredients

  • 12 fresh duck eggs
  • 1L Water
  • 25g Loose leaf black tea (or about 10 teabags)
  • 40g food grade sodium hydroxide (NaOH)
  • 50g Salt
  • 150g Beeswax

Instructions

  1. Bring water to a full boil in a large stainless steel pot. Remove from heat, add teabags and salt and mix until the salt has fully dissolved.
  2. Let the tea cool down to room temperature, and then remove the teabags.
  3. In a well-ventilated area, and wearing protective gloves, slowly pour in the sodium hydroxide. Mix with a stainless steel utensil until dissolved.
  4. Carefully add the eggs to the mixture, one by one. I used a stainless steel slotted spoon to lower them down into the liquid.
  5. Cover the pot with a lid and label it with the date and content. Store the pot in a cool, dark place, somewhere safe where nobody will accidently open it or cause the liquid to spill out, for 24-30 days (lower end of the range in the summer, higher end of the range in the winter).
  6. Now, it is time to remove the eggs from the sodium hydroxide tea and to cure them in a sealed environment. Melt beeswax in a small double-boiler (I used a heat-proof glass dish placed inside a saucepan, submerged in water about halfway).
  7. While the wax is melting, bring out your pot of eggs from their safe storage space. Wearing gloves, scoop the eggs out of the sodium hydroxide tea one by one with a slotted spoon. Rinse them well until cool water, and place them on a clean towel to dry.
  8. When the beeswax has melted, pick up an egg (with gloves on!) and dip it halfway into the wax. Place the egg wax side-up in an egg cup for the wax to dry. Dip the remaining 11 eggs in the wax and set them in their egg cups, then go back to the first egg and dip it again in the wax (on the same side as before). You want to dip each egg in the wax three or four times per side so that the egg is completely encased in a solid layer of wax.
  9. Once all the eggs are encased and dry, place them in a container, and them in a cool, dry place (out of the refrigerator) for another few weeks, or for up to three months. They don't keep well once opened, so open only what you need at a time, and leave the others encased in beeswax until you are ready to serve them.

Notes Make sure to follow the safety measures and evaluation process outlined on my blog post. Good luck!

Nutrition Calories146 cal  Fat 1 g Carb 5 g Protein 27 g 

 

Safety and Quality Evaluation

(or How can I be Sure this won’t Kill Me?)

Once your eggs have sat enough time in their beeswax shells, it is time to break them open and enjoy them. But how can you tell if your eggs are good to eat? Here is a checklist you can go through as you open your century eggs to assess their quality before you put them in your mouth (or serve them to your guests!):

Before Removing the Beeswax

  • No eggshell is exposed
  • There is no mold
  • When shaken, there is no watery sound
  •  

    While Removing the Beeswax and Eggshell

  • The eggshell has no cracks
  • The egg separates easily from the shell

After Removing the Eggshell

  • The egg is semitransparent in deep brown, dark-green, or tea-brown
  • The egg is intact and elastic, with no turbidity
  • The egg may have little “pine-floral crystals” (see picture below)

 

 Century Egg

 

After Cutting the Egg into Pieces

  • The yolk is light green, tea-brown, and orange-brown in color,
  • The yolk is hard or semi-hard, and sticky but not flowing
  • The smell of ammonia is present, but not overpowering

Ok. Are you still with me? If your egg has passed the evaluation so far, it is beyond safe for human consumption. Time for the final ordeal: the taste test!

  • The egg has a cooling mouth feel
  • The egg has a clean, slightly salty, slightly peppery taste

Or in the words of Fuchsia Dunlop, it should “taste quite like eggs, but more intense and delicious”!

Congratulations! You have made century eggs!

 

 

References

 Entire Post by Joëlle  https://www.kindredkitchen.ca/

Dunlop, F. (2008). Shark’s Fin and Sichuan Pepper : a Sweet-Sour Memoir of Eating in China. London: Ebury Press.
Dunlop, F., & Terry, C. (2013). Every grain of rice: simple Chinese home cooking. New York: W.W. Norton.
Wang, J., & Fung, D. Y. C. (1996). Alkaline-Fermented Foods: A Review with Emphasis on Pidan Fermentation. Critical Reviews in Microbiology, 22(2), 101–138. doi: 10.3109/10408419609106457

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