Swallow Nest
Latin: Collocalia fuciphaga
Origin:
Edible swallow's nests are produced by swiftlets (Collocalia fuciphaga). These birds are from the same Apodidae family as the common swallow, but they are smaller in size, averaging only 9 mm in length, weighing about 15 to 18 g, while swallows can grow up to 17 mm and weigh around 30 g. Also, the tails of swiflets are shorter with feathers that are rectangular in shape, while swallows have a longer tail and feathers that shaped like scissors. Swiftlets' lower legs have a row of small feathers on the outer and inner side. Most swiftlets have dull dark grey-brown to black plumage with variable areas of grey to white on the underparts or at the base of the tail.
Swallows live in the northern part of the earth, commonly seen in China, India, Europe and North America. Swallows make their nest from tiny tree branches, dry grass, or even mud, and their nests are certainly not edible. In contrast, swiflets, which can only be found in the tropical coastal areas, make their nest by regurgitating gelatinous nest-cement, or the saliva. Their saliva is produced by a pair of large salivery glands under the tongue. The precious swiftlet nests are therefore actually the dried saliva of swiftlets, and they are the only swallow's nests constructed entirely from saliva. It is the only edible swallow's nest beneficial to human body. Swallow's nest is also referred to as bird's nest.
These edible nests built by swiftlets are found in caves and cliffs in offshore islands of North Borneo, Indonesia, Malaysia, Thailand, Vietnam and the Philippines. Small colonies of swiflets are also found in some remote areas of Hainan and Fukien of China. In addition to cave swallows, there are also house swallows farmed in these areas. Swallow nests that originate from different places have different textures.
Swallow nest consumption first appeared in Gu Ming's Guidelines on Diet (circa 1350) of the Yuan dynasty in China. At the time, the Chinese were already bartering swallow nest from north Borneo with china and metals. By the Ming dynasty, more nests were imported. In the Jin Ping Mei Tsz Hua (1617) of the Ming dynasty, it was clearly stated that swallow nest and shark fin were the food of the rich. Thereafter, numerous citations of ancient texts have confirmed swallow nest as a highly-prized delicacy of the upper class. People especially those riches love it and consider it as one of the most precious tonic food they can have. As a food and a tonic, it is said to be highly nourishing, containing with elements which can stimulate cell and epidermal growth. Taken regularly, so the tradition says, the skin will be glowing and delicate. Swallow nest is also good for the lungs. It is beneficial to the elderly and those who have just recovered from illness.
Classification of Swallow Nest
Swallow nest is classified into cave nest and house nest in terms of sourcing. Cave nests are those constructed by swiftlets in caves and on cliffs. Owing to the harsh natural climate and environment, the nest is firm, hard and deep in color. It is not as well shaped as house nest and exhibits higher impurities. Cave nest is crunchy with a low swelling capacity that lengthens the time for it to swell when preparing.
House nest refers to the nest built in wooden-roofed swallow farmhouses that are humid and dark. The interior temperature is kept at around 30 ¢J. Brightness and humidity (about 90%) are also maintained to the conditions similar to the bird's natural cave habitat. Swiftlets leave the farmhouse to find food in the wild in the morning and returns in the evening. Since the farmhouse provides the swallows a better habitat, house nests are much cleaner with less impurities and feathers. They also have an intact cup shape, and have a high swelling capacity.
Swallow nest is also classified according to colors: white, blood-red and yellow, even grey and purple. Different colors exist in the nests because swiftlets feed on different food. White nests are generally smooth, while yellow and blood-red nests are crunchier because they contain more minerals than white nests.
The market generally differentiates swallow nest based on its appearance: the natural whole nest cup, nest strips, nest pieces, and the irregular shaped nest cake processed from nest pieces. The whole nest cup looks better, has the highest nutritional value and is priced the highest. Most nest cups come from house nests. During processing and shipping, some nest cups are broken into strips and pieces and they are then sold as such. Their swelling capacity and prices are lower but the nutritional value is the same as that of nest cups.
However, because cave nests contain more impurities and feathers, the nests may be required to be broken during processing in order to remove dirt and feathers. After disintegration and removal of feathers and impurities, the nest may be sold in nest strips and nest pieces, or molded into the shape of a nest cake. These nests generally contain less nest-cement and are of less nutritional value.
Harvest Time
Swallow nests are harvested 3 times per year. The first period is from November to March, which is immediately followed by the second and third periods. Rainfall is particularly substantial during the first period. This provides an environment highly suitable for the growth of tiny animals and plants, giving swiftlets plenty of food. Swiftlets in this period grow particularly strong and thereby produce copious amount of saliva. Swallow nests harvested during this period are the best because they are big and thick, containing fewer impurities.
The second harvesting period is during the dry season, between April and June. There is a decrease in food supply for the swiftlets and this results in the nests being thin and loose and the nest threads thick. The shape and the swelling capacity of the nests are poorer than those of the first period.
The third period is well within the drought season, between July and October. During this period of the year, the swiftlets are weak. Their secretion of saliva is low and feathers come off more easily. Swallow nests that are constructed are smaller in size, containing more impurities and feathers and have a very poor swelling capacity.
Grading
The grading of swallow nest is based on the proportion of nest-cement. Low grades are given to nests with many feathers incorporated in the nest-cup, with softened bases. Good quality nests are distinguished by the firm basal attachments and a comparatively large proportion of nest-cement with few feathers in the nest-cup.
The best swallow nest is in the shape of a cup or a boat. Swallow nest can be triangular in shape if it has been built in the corner of two adjacent walls. Nests that are broader in width rank higher and are pricier. However, for nutritional value the shape does not matter.
Good nest should be of natural color, containing no mud and other impurities. The color of the white nest is an actual ivory. The yellow nest and the blood-red nest are colored yellowish gold and red respectively. The variations and intensity in the color are due to the difference in the mineral contents of the food the swiftlet eats. Regardless of their colors, swallow nests expand when soaked in water, but in different degrees. The coloration of the swallow nest will fade a bit upon soaking; however, the water used for soaking should remain colorless. If a nest looks extraordinarily white, it may have been bleached. The nutritional value of bleached nest is obviously affected; it could also be harmful to health.
Swallow nests that have finer, denser nest threads, or are bigger and thicker in volume are considered better. Nests are also selected by smell. A real swallow nest retains a little bit of a fishy smell of the swiftlet's saliva. When cooked, it releases a light aroma resembling the aroma of an egg white.
Cleaning the Nest
Processing swallow's nest is a long, tedious and labor intensive process. First the raw swallow's nest has to be soaked for 2 to 48 hours for them to absorb water and expand. Depending on the kind of nests, the time required for them to expand or swell is different. The water need not be retained after soaking.
The next step is to separate the feathers from the edible cement content. Larger feathers can be easily plucked off with a pair of forceps.
Finally, place the expanded swallow nest on a double-layer stainless steel strainer. Rinse with tap water and at the same time tear the threads of the nest apart to remove the impurities.
Fake Nests
Some merchants use chemicals to process and clean swallow nest. One can tell the difference between chemically treated processed nests from those of untreated materials by the shine of the cement strands. Nest cement that is too shiny and smells strangely is likely the result of chemical additive. Cleaned nests that are too red in color could be the result of dye additives which will dissolve after soaking.
Other illegal merchants may coat a layer of egg white or jelly on poor quality imitations. This would add extra weight. The fake swallow nest would reflect light and look opaque. In contrast, light will penetrate through a genuine swallow nest. Some fraudulent swallow nests are made of "Malaysian rubber" or "pig skin". The former smells and tastes acidic and does not contain nest threads while the latter releases oil after soaking in water. Some fake ready-made swallow nest and nest pieces are made of resin or bleached laver.
As a way of differentiating qualities, price is a fair guideline. The higher the quality of a swallow nest, the greater the nutritional value, expanding capacity (applied mostly to white nest as red nest generally does not expand as much) and beauty.
Exporters and Users
The world's major producers of swallow's nest are Indonesia, Malaysia and Thailand. Indonesia produces 80% of the world production. Most of the product is exported to Hong Kong and Singapore.
Properties:
Sweet in flavor, mild in nature, it is related to the channels of the lung, stomach and kidney.
Functions:
Nourishes yin to maintain skin tone, tonifies qi (energy) and reinforces the system, strengthens the lungs and prevents coughing, vitalizes the constitution and prolongs life.
Applications:
Swallow's nest is used to treat consumptive diseases, tuberculosis, cough and phlegm-dyspnea (difficult breathing), asthma, hemoptysis (coughing blood), hematoma (mass of clotted blood that forms in a tissue, organ, or body space as a result of a broken blood vessel), prolonged dysentery, chronic malaria, dysphagia (difficulty in swallowing), hiccups, regurgitation and general weakness.
1. For dry coughs with little sputum and/or night sweat due to yin deficiency of the lung:
4 g swallow nest, 4 g white fungus, 10 g rock sugar, double-steam and consume; or use Sichuan fritillary bulbs with a pear on swallow nest. (for 4 persons)
2. Nourishes yin to maintain skin tone, reinforces the lung and deficiency of the body; helps to treat consumptive diseases; and for fatigue, thinness, poor appetite, weak stomach, etc., due to prolonged illness:
15 g swallow nests, 4 bowls (or cups) milk, double-steam and consume; or use chilken and beef juice with swallow nest. (for 4 persons)
3. Nourishes yin to maintain skin tone, vitalizes the constitution and prolongs life:
40 g swallow nests, 80 g crushed rock sugar, double-steam and consume. (for 4 persons)
4. For convalescence or to recover health after illness; complement other treatments to combat degenerative diseases such as nephritis and lung disease:
32 g swallow nests, 40 g white fungus, 10 pieces American ginseng, 80 g crushed rock sugar, double-steam and consume. (for 4 persons)
5. For convalescence or to recover health after illness or surgery; nourish the kidney, the lung, qi (energy) and blood:
16 g swallow nests, 1 black-bone chicken, 10 g cordyceps, 30 g dangshen, 15 g longan aril, 10 g wolfberry fruit, double-steam and consume. (for 4 persons)
6. Nourishes yin to clear heat from the lung, arrests coughing, relieves asthma:
32 g swallow nests, 8 preserved dates, 15 g almond, 10 g sha shen, rock sugar, double-steam and consume. (for 4 persons)
7. Nourishes yin to clear heat from the lung, relieves asthma replenishes the heart and the spleen:
32 g swallow nests, 12 red dates (unseeded), 20 ginkgoes, 40 g white fungus, rock sugar, double-steam and consume. (for 4 persons)
Dosage and Administration:
For a serving of an average adult about 10 g of cleaned dry nest is recommended.
The nutritional benefits of swallow nest can be shown only when it is consumed regularly. For general health improvement it is recommended to have a bowl's nest once a week; or better still, one tablespoon (about 2 g of dry nest) taken before meal in the morning every day.
For convalescence or as complementary treatment to combat diseases, it is recommended to take one tablespoon in the morning and one in the evening before meal every day. Each time, use a clean spoon when serving to ensure hygiene.
1. Soak white swallow nest in cooled boiled water for 2 hours, yellow nest for 4 hours and blood nest for 12 hours to enable it to expand. Discard the water after soaking;
2. Place the soaked nest on one palm and pick off small feathers with a pair of stainless steel forceps;
3. Place the nest on a double-layer stainless steel strainer; rinse with tap water and at the same time tear the threads of the nest apart to remove impurities;
4. Then cut up and place in a double-steaming pot with hot water just covering the nests;
5. Put the pot into a large pan that can house the pot. Add hot water into the pan to the level that covers half of the pot;
6. For white nest, double-steam over low heat for 30 minutes; for yellow nest, 35 minutes; and for blood nest, 90 minutes;
7. Add rock sugar or salt to season and serve.
PS. For regular consumption, it is more convenient to prepare one week's quantity. After cooling the cooked swallow nest, wrap it and store it in refrigerator. Seasoning should be added only upon serving.
PPS. The pre-cooked swallow nest can be stored for a maximum of one week. Making too much and leaving it in the refrigerator for too long would risk the nest turning bad and sour.
Cautions on Use:
For those swallow's nests that show yellowish or blackish colors, or are spoiled by mildew, they are likely toxic and shouldn't be consumed.
Since swallow nest is the condensed saliva of swiftlet, it should not be cooked in temperature over 100 ¢J, or else it would dissolve into water, particularly white nest. In addition, the cell division inducing hormone contained in swallow nest stays active at around 80 ¢J. Boiling will destroy the hormone and render the medicinal properties worthless.
Double-steaming swallow nest over low heat will keep the internal temperature of the double-steaming pot at around 80 ¢J, which not only prevents swallow nest from dissolving but also retains the valuable protein and nutrients. Using an electric double-steamer is a convenient alternative. However, over double-steaming could still turn swallow nest into water. So note the time and keep watching when you are double-steaming swallow nest.
Never heat swallow nest in a microwave oven. The relatively high temperature could destroy the nutrients in the nest. Wet nest should be dried by just leaving it in room temperature for 30 minutes. Beware not to dry it by baking or by direct sunlight.
Reference Materials:
Zhang Lu, Success in Materia Medica (1695): "It is the most gentle food there is."
Wu Yiluo, Reorganizing Materia Medica (1757): "(It) greatly nourishes the lung yin, thus reduces phlegm and stops coughs. It nurtures purely, and is the best medicine for recuperating from damages and tuberculosis. All diseases that are caused by lung deficiency, that cannot be cleared and go down, can all be treated by this. It also whets the appetite, treats tuberculosis and dysentery, benefits rashes of young children...(The blood swallow nest) moistens and lowers breath, and is particularly effective treating hiccups."
Huang Gongxiu, Probes on Materia Medica (ca 1736-1796): "Enters the lung and it generates air; enters the kidney and it generates water; enters the stomach and it nurtures the spleen. It nourishes yet is not dry; moistens but does not stagnate. It is the most gentle and the most delicious medicine there is."
Toxic or Side Effects:
For those swallow's nests that show yellowish or blackish colors, or are spoiled by mildew, they are likely toxic and shouldn't be consumed. Otherwise, good swallow nest is non-toxic.
Modern Researches:
Every 100 g of dry swallow nest contains 49.9 g of water-soluble protein (including amido nitrogen, monoamine nitrogen, non-amino nitrogen, arginine nitrogen, humin, histidine nitrogen, lysine nitrogen and cysteine nitrogen), 30.6 g carbohydrate (glycoprotein and mucin), 4.9 g iron, 2.5 g inorganic salt (including potassium, sodium, calcium, magnesium, sulfur, phosphorus, silica and other trace elements), 1.4 g fiber and 10.7 g others. (Sources: Dictionary of Traditional Chinese Medicine, The History of Chinese Medicine and the Nutrition Table.)
The energy value per 100 g swallow nest is 345 kilocalories.
In the article "Yan Wo Kao" (The Investigation on Swallow Nest) in Mingpao Monthly Vol. 231 (May 1985), Prof. Y. C. Kong and Prof. P. S. Kwan of the Chinese University of Hong Kong reported their research on the tonic food. Based on repeatable results of in vitro exposure experiments the researchers have discovered that swallow nest contains a "cell division inducing hormone" and an "epidermal growth factor" that can stimulate the growth and division of cells, thereby enhancing tissue growth, cellular regeneration, and cell-mediated immunity in humans.
Their investigations have provided scientific evidence that supports the traditional beliefs that swallow nest can facilitate metabolism, nourish the skin tone, replenish strength and vital energy, accelerate the recovery from diseases and reinforce immunity.
The specific animal proteins in an edible swallow nest have the following three functions;
1. To stimulate the regeneration of cells.
2. To enhance cell-mediated immunity.
3. To enhance the resistance of an individual to X-irradiated damage.
This active protein is easily absorbable by humans, making it unique among foods.
The report also states that the "cell division inducing hormone" in swallow nest is activated at around 80 ¢J, while overheating it would destroy the nutritients. This is why double-steaming is recommended in the Cooking Procedure.
But Dr. Gu Hsiao Pei takes a somewhat different view from Prof. Y. C. Kong on the potential benefits of epidermal growth factor ( EGF) of swallow nest. In his column entitled ¡§Are you suitable to have swallow nest?¡¨ (Hong Kong Economic Journal March 7, 2006), Dr Gu allows that as swallow nest comes from the saliva of swiftlets (Collocalia fuciphaga), so it is possible that saliva of other animals also contain EGF. Since EGF serves to stimulate cell proliferation, this may explain why animals tend to lick their wounds with saliva, probably an instinctive use of saliva in healing wounds. However, argues Dr Gu, it is one thing for EGF to help heal wounds, it is quite another for EGF to help proliferate cancer cells in cancer patients. As breast cancer patients are advised to abstain from having clam pastes because the estrogen in the food could cause cancer cell proliferation, cancer patients should also be so advised about having swallow nests.
In addition to stimulating the proliferation of cancer cells, EGF could also promote three factors that allow the proliferation of blood vessels. These three factors are vascular endothelial growth factor (VEGF), beta fibroblast growth factor (bFGF) and transforming growth factor alpha (TGF£\). Cancer cells depend on blood vessels to transmit nutrients to them for growth. For this reason, cancer patients must suppress blood vessel proliferation. One way doing so is to abstain from having swallow nests. Also, the cause of macular degeneration, another common illness for elders, is the proliferation of new blood vessels on retina. For these patients, writes Dr Gu, they should also abstain from having swallow nests, or else their body would manufacture some unnecessary new blood vessels.
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