Bury St Edmunds private chef Lilian Hiw, of Lilian’s Kitchen, looks at ways eggs are preserved in Asia and shows us how to enjoy them
One day, while scrolling through Facebook, I came across the term ‘water glassing’. I did a quick Google search and found myself intrigued by the different ways eggs have been preserved over the years. I was reminded of my favourite eggs from Asia – salted duck eggs and century eggs, which inspired this column.
This may also be of interest if you have just started keeping chickens for eggs, as you may find yourself with a surplus of eggs in the spring and summer months and like to maintain a supply over the winter, when the chickens lay fewer eggs.
Longer term storage:
WATER GLASSING
A time-honoured method of preserving eggs is to soak them in a solution of water and, traditionally, sodium silicate. However, this method seemed to produce egg whites that won’t whip up and there were concerns about the health benefits of using sodium silicate.
Calcium hydroxide, also known as pickling lime, is now used instead. The lime seals the shell of the egg, stopping the exchange of air and keeping the egg fresh for, believe it or not, 18 months to two years.
Tips:
• Eggs should be freshly laid, unwashed but wiped clean to leave the natural ‘bloom’ (protective glaze) on the eggs intact.
• Filtered water is recommended as the chlorine in tap water can remove the bloom.
OILING EGGS
Coating eggs with a substance that makes the shell impermeable is another age-old approach. Eggs can be coated with lard, butter, wax or food-grade mineral oil.
Tip:
• Butter has a shorter shelf life as it becomes rancid. If you prefer the fragrance of butter, I would suggest clarifying the butter to prolong its use. The clarification process removes milk solids and water, leaving pure fat, which is more stable.
BURYING EGGS
Another classic method is to bury the eggs in various materials such as wood ash, wheat bran or salt. The wood ash and wheat bran keep the eggs dry and cool, helping to extend their shelf life. Salt draws moisture out of the eggshells, creating an environment that inhibits the growth of bacteria and mould.
Tip:
• Eggs buried in salt will taste slightly salty and the whites may not whip up as well as fresh egg whites.
MODERN TECHNOLOGY
Electricity and modern technology have made egg preservation more reliable and accessible.
REFRIGERATING
Keeps fresh eggs at a constant cool temperature, prolonging their freshness.
Tips:
• Keep them in the main body of the fridge rather than on the door to maintain a consistent temperature.
• Remove eggs from the refrigerator and allow them to come to room temperature before use. In baking, eggs mix more easily with batter and dough, resulting in a better texture in baked goods. For aeration, egg whites whip to a greater volume if you are making meringues, soufflés or light cakes etc.
FREEZING
Eggs can be frozen for up to one year.
Tips:
• For versatility, crack the eggs and separate the yolks from the whites. This allows you to use them for different recipes as needed.
• To control portion size, freeze in ice cube trays. Once frozen, pop them out and store in plastic freezer bags.
• Whisk a pinch of sugar or salt into the yolks to prevent them from becoming too gelatinous.
• Do not freeze boiled eggs as they can become rubbery.
PASTEURISING
Eggs are heat treated to kill potential pathogens such as salmonella, making them safer for consumption in recipes that call for raw or partially-cooked eggs. You can buy pasteurised egg whites and yolks in cartons or bottles.
VACUUM PACKING
Air is removed from the package before it is sealed. With reduced oxygen, bacteria and mould would struggle to grow and reproduce, extending the shelf life of the eggs.
Short-term storage:
PICKLED EGGS
For more immediate consumption, why not change things up and make some pickled eggs? Hard boil some eggs, cool, peel and place in a sterilised jar. Pour in a warm brine of vinegar, water, salt, sugar and any pickling spices and submerge the eggs completely. Cover with a tight-fitting lid. Store in a cool, dark place and you can enjoy them in a week. Great as a snack on their own or why not add them to Niçoise or potato salad?
Tip:
• Add slices of garlic, onion or beetroot slices to add flavour and colour.
CENTURY EGGS
Century eggs (pídàn) are a traditional Chinese delicacy, they are also known as thousand-year eggs, hundred-year eggs, millennium eggs, alkalised eggs or preserved eggs. Contrary to the myth that century eggs are made by soaking in horse urine, the actual process involves covering the eggs in an alkaline paste of wood ash, salt, clay, quicklime and tea, then coating them in rice husk and storing them in a sealed container. They are left to cure for several weeks to months – not a century, despite the name.
They are ready to eat with no cooking required. Simply remove the outer coating of paste and rice husk, wash the egg and just peel it like a hardboiled egg. Once the shell is removed, you will see that the egg white has turned into a translucent amber black colour with a firm, jelly-like texture. While the yolk has developed soft green and dark grey rings and a creamy, custard-like texture. They tend to have a slight aroma of ammonia and sulphur, due to the breakdown of egg proteins during the preservation process.
How are they served?
This unique delicacy can be enjoyed on its own or paired with other dishes to add flavour and texture.
In Cantonese cuisine, century eggs are often enjoyed as a cold appetiser paired with pickled ginger or as a side dish, sliced and drizzled with black vinegar and soy sauce. They’re also delicious chopped and served over chilled silken tofu with a drizzle of soy sauce and sesame oil – I like mine with the addition of crispy chilli oil.
Stir-fried Chinese spinach with century eggs and salted duck eggs is a popular dish at home and in restaurants. A classic dish in dim sum restaurants or at home is rice porridge (congee) with century eggs and lean pork.
My grandmother and mum used to make ‘triple-coloured eggs’ – century eggs and boiled salted duck eggs are chopped and mixed with beaten fresh eggs then steamed to a custard-like texture, which we would eat with rice.
CHINESE SALTED DUCK EGGS
A cherished delicacy in Chinese cuisine, it is made by soaking raw duck eggs in brine and then cooking them by boiling or steaming.
The white is firm and slightly salty, but the yolk is the real hero! They are like an umami bomb – rich and savoury, adding extra richness and a unique depth of flavour to both savoury and sweet dishes. The yolks have a unique texture, similar to a tender mashed roasted chestnut, and will add indulgence to any dish. Salting these eggs is not so much a method of long-term preservation as it is a process of creating amazingly tasty eggs that can be eaten on their own or used to elevate other dishes.
Duck eggs are the ideal choice as the yolk is larger and the taste and texture is creamier. Chicken eggs can be used if you can’t get hold of duck eggs.
Simply wash and dry the eggs, then roll each one in Chinese wine to add flavour and kill any bacteria. Place them in a sterilised glass jar with a lid, pour in cooled salt solution and cover the eggs completely. I scrunch up some greaseproof paper and place it on top of the eggs to stop them floating and to keep them completely submerged in the brine.
Alternatively, you can roll cleaned and dried eggs in Chinese wine followed by salt, then individually wrap in cling film and leave in a cool dark place until ready.
Patience is required as you need to wait at least 30 days for the yolks to solidify and harden and the whites to break down and become slightly watery. Test by boiling one of the eggs and if it’s not salty enough, leave it to cure for a few more days or until you’re happy with the result. Once ‘ready’, remove them from the brine; or wash off the salt to stop the curing process. Store in a sealed container in the fridge for one to two months.
How are they served?
Traditionally, salted duck eggs are boiled whole, sliced in half on the shell and served with rice porridge (congee) for breakfast and the yolks are used in moon cakes and rice dumplings (zongzi).
Creative culinary ideas from around the world have seen salted duck egg yolk used in both sweet and savoury food, as fillings in breads, sweet and savoury pastries and the popular steamed salted egg lava buns in dim sum restaurants. They also feature in stir-fries – famously with crab and prawns, or meat and vegetables – and are added to fried rice to enhance flavours.
Deep-fried fish skin and potato crisps are delicious with a salted egg yolk coating, look out for them. Try grating them over pasta and noodles for an instant umami boost and texture. They are even delicious in ice cream… the possibilities are endless.
Tips:
• You can buy vacuum-packed salted duck egg yolks from your Asian grocer.
• If you only need the yolk for cooking, you can bury the yolk directly in salt. This will produce flat, rather than round, egg yolks.
Wishing all of you a very Merry Christmas and a Happy New Year. Until the next time, take care of yourselves.
Pictures courtesy of Tung Lok Group Singapore, Nellia Ho and Lilian’s Kitchen
Private chef Lilian Hiw
Author of Lilian’s Kitchen Home Cooked Food
Visit www.lilianskitchen.co.uk
