From a health perspective, eggs have been given a significant
reprieve in recent years. Although the yolk contains cholesterol,
it is now known that cholesterol already in food contributes very
little to the levels inside your body, and it is the cholesterol
made inside your body from saturated fat (found in fatty meat, full
dairy products and processed food) that you really need to worry
about.
The British Heart Foundation recommends that those with high
cholesterol limit their intake to four hen's eggs per week while
the American Heart Association recommends limiting cholesterol
intake to 200 mg per day for those with heart disease, and 300 mg
for the rest of the population - an average hen's egg contains
around 200 mg.
In fact the cholesterol (and fat) within an egg is confined to
the yolk, and so you can use egg whites more freely. Eggs contain a
wealth of nutrition; they are an excellent source of high quality
protein, and are high in energy processing B vitamins riboflavin
and B12 (an important source if you avoid meat). They also provide
minerals such as zinc, iron and phosphorous, and are a valuable
source of the fat-soluble vitamins D and A.
Just when I thought all methods of egg-cooking had been
exhausted (boiling, poaching, frying, coddling etc) I came to China
and discovered many, admittedly far more involved, egg preparation
methods.
Tea eggs (cha ye dan) can be seen bobbing in caddies down many a
street throughout China, the cracked shells disclose their
delicious whites, marbled brown with tannin and soy sauce. In fact,
many other ingredients besides tea are used in the infusion. The
eggs are initially boiled in water for a few minutes, removed and
their shells lightly tapped to crack them. Soy sauce, star anise,
cassia bark, pepper corns and dried mandarin peel may then be added
to the water and the eggs returned to simmer in the brown
concoction for 2-5 hours.
Thankfully, no matter the production method, Century eggs (pi
dan) have not been hanging around for the last 100 years.
Traditionally, the eggs were encased in a mixture of clay, ash,
lime, salt and rice straw and left for weeks to months. The
alkaline nature of this concoction causes the pH of the egg to rise
resulting in a type of alkaline fermentation. Consequently the
white turns brown and transparent whilst the yolk develops a green
color with a strong sulfur odor. Typically these eggs are served
sliced on their own, or added with pork into rice congee to make
pidan shourou zhou.
Eggs play a significant role in daily diet.
Quanjing
Steamed egg - zheng ji dan geng - is a savory dish with an
almost custard-like consistency. It is made by whisking two eggs
with half a cup of water and a dash of soy sauce, the mixture is
then placed in a ramekin, sat in a pan with boiling water and
steamed for 10 minutes until the egg is set. This is then served
with a few drops of sesame oil and chopped spring onions on
top.
Of course hens are not the only fowls producing eggs. Quail
eggs, a delicacy where I'm from, are inexpensive and widely
available here. They are often added whole to stews or served hard
boiled. Their cholesterol concentration is higher but their overall
size is smaller - two and a half quail's eggs contain the
cholesterol equivalent of one hen's egg.
Duck eggs are also abundant here and are typically salted in
brine or packed into salted charcoal to produce xian ya dan (salted
duck eggs). This results in a concentrated vivid yellow yolk and
liquid white, the eggs are then cooked before being eaten. Be
cautious, duck and goose eggs are obviously larger, but also have a
higher cholesterol concentration - a duck egg contains around 620
mg cholesterol, whilst one goose egg contains 1,225 mg - equivalent
to around six hen's eggs.
This nutrition-related column is written by Nina Lenton, a
qualified dietitian living and working in Beijing. Contact her at
nina.lenton@bjhealthcare.com.
(China Daily February 20, 2008)
