Archive for July 18th, 2006
hkfsta.com.
淺談燕窩的科學研究
Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University
Shun Wan CHAN
Abstract: Edible bird’s nest is one of the widely used health foods in Chinese communities. The market generated by it is increasing because it exhibits a lot of beneficial effects to human beings. For its high market value, fake edible bird’s nest and misleading promotional description emerged. This article briefly reviews the scientific research on authentication technologies and pharmacological effects of edible bird’s nest. It is expected that people’s knowledge on edible bird’s nest could be enhanced.
摘要：燕窩在華人社會是其中一種非常普及的健康食品。一直以來，人們都相信燕窩有多種不同之效用，因此燕窩 市場不斷在擴展。由於燕窩的價值絕不便宜，故此假燕窩和一些帶有誤導性的推銷描述不斷在市場上出現。本文將簡略 回顧一些有關燕窩辨別真偽的技術與藥理效用之科學研究，希望藉此能加深社會對燕窩的認識。
Background
Swiftlets (collocaliini) are tiny insectivorous birds that are distributed from the Indian Ocean , through Southeast Asia and North Australia to the Pacific[1]. Amongst various species of swiftlets in the genus of Collocalia, only the nests of four species habituating in the Southeast Asian region have commercial value because of human consumption. They are Collocalia fuciphaga, Collocalia germanis, Collocalia maxima and Collocalia unicolor[2]. Collocalia species, average 6.5g in weight, have glossy plumage[1]. Their nests are constructed with salivary glue, a cementing substance, and may incorporate other materials such as vegetation or feathers. It takes about 20 days to finish the nest. The edible bird’s nest ( 燕窩 in Chinese) making up with purely salivary glue are much more expensive than those incorporating with other materials (see Figure 1 in p.40).
In Hong Kong and in Chinese societies throughout the world, traditional Chinese medicine (TCM) is commonly used to treat diseases and enhance health. It is believed that TCM herbs have wide-ranging effects for enhancing health, lowering risk of diseases and promoting life span [3,4,5]. Being one of the TCMs, edible bird’s nest is believed to have health enhancing effects such as anti-ageing, growth promoting and immunoenhancing properties. In fact, the medicinal use of edible bird’s nest can be traced back to 17th century[6]. However, edible bird’s nest is different from most of the TCMs. It is not only a medicine to make people healthy but also a pleasant food. Traditionally, it is double boiled with rocky sugar to make a delicacy known as “bird’s nest soup”.
Although the size of Collocalia is small, the market generated by it is tremendous. The estimated market of edible bird’s nest in 2004 is worth about HK$ 3 billions in Hong Kong . The local market is the world’s largest consumer of edible bird’s nest[2,7]. The annual percentage increase of the local market is in doubledigit[7]. It may be due to the fact that Hong Kong people are more and more concerned about their health and the status of TCM has risen after a series of government policies on TCM. Moreover, a dual nature of edible bird’s nest, that could be treated as medicine or/and food, may play a role. In the past, people could only buy dried edible bird’s nests. For the advancement in food technology, large variety of edible bird’s nest related products emerge to the market. They are readily to serve products. No cooking process is required. Amongst those new products, most of them are still in the traditional form as bird’s nest soup, such as instant bird’s nest in different concentrations. Some instant bird’s nest may also supplement with other TCMs. Apart from the traditional form, there is a trend of using edible bird’s nest extract as one of the chief ingredients of the products. These products focus mainly on the medicinal use of edible bird’s nest. However, some of them may exaggerate the therapeutic use of edible bird’s nest. For the limited supply and high price of edible bird’s nest, it is not uncommon to hear reports of fake edible bird’s nest in the market. The imitation substitute commonly used is the edible plant-exude, gum karaya or sterculia[8]. Recently, there are reports of fake edible bird’s nest made from fishes’ skin, mushroom or algae in China [9]. Therefore, it is a great concern on authenticating the genuineness of edible bird’s nest. In this review, the author will briefly summarize some advanced technologies in authenticating edible bird’s nest. The medicinal benefits of edible bird’s nest with contemporary scientific evidence will also be given.
Authenticity of Edible Bird’s Nest
The first comprehensive report on authentication of edible bird’s nest can be traced back to the early 1990s. Sam et al., (1991) demonstrated the possibility to use scanning electron microscopy, energy dispersive X-ray microanalysis, flame atomic emission spectroscopy, inductively coupled plasma-atomic emission spectroscopy, ultraviolet-visible spectroscopy and other physico-chemical techniques to ascertain the authenticity of edible bird’s nest[8]. Since they only made a comparison with some imitation bird’s nest with substances from plant origins, it limited the generalizing ability of the techniques to other imitation materials. In addition, they relied on sophisticated equipment. It is hard for commercial testing laboratories to carry out. Recently, a research team in China has developed a simple but accurate and reliable spectrophotometry method to determine edible bird’s nest content[10]. It could also be used to differentiate genuine edible bird’s nest with saliva, pig’s skin and Tremella fucifomis[10]. The method is based on the reaction between N-acetylneuramic acid and ninhydrin in acid solution. The method evaluates the internal content of N-acetylneuramic acid, a nine-carbon sugars, which is one of the major components in edible bird’s nest.
Nutritional Content and Medicinal Use
Edible bird’s nest contains mainly carbohydrates, amino acids and mineral salts. The major ingredients of edible bird’s nest are glycoproteins[11]. Amongst the carbohydrates in edible bird’s nest, sialic acid (9%) is the major one. It was found that exogenous source of sialic acid may contribute to neurological and intellectual advantages in infants[12]. However, the nutritional and biological mechanisms of sialic acid in human body are still under investigation. The other major carbohydrates include 7.2% galactosamine, 5.3% glucosamine, 16.9% galactose and 0.7% fucose[11].
Amino acids and mineral salts are also important components in edible bird’s nest. Three non-essential amino acids (aspartic acid, glutamic acid, praline) and two essential amino acids (threonine and valine) can be found[11]. They could facilitate normal body functions such as repairing and immunity. Edible bird’s nest is rich in mineral salts. It contains high content of sodium and calcium. It is because the source of edible bird’s nest is derived from saliva Collocalia inhabiting mainly in limestone caves. In addition, low levels of magnesium, zinc, manganese and iron are also detected in edible bird’s nest[8].
In spite of the long history of using edible bird’s nest for medicinal purposes, there are not many scientific researches related to the therapeutic use of it in literature. The first scientific evidence was given by Ng et al. (1986) in Hong Kong. Edible bird’s nest aqueous extract was found to potentiate mitogenic response of human peripheral blood monocytes to stimulation with proliferative agents, Concanavalin A and Phytohemagglutinin A[13]. It suggested that edible bird’s nest might possess immunoenhancing effect by aiding cell division of immune cells.
One year later, other scientific evidence was published by Kong et al. They demonstrated an epidermal growth factor (EGF)-like activity in aqueous extract of edible bird’s nest that stimulated the DNA synthesis in 3T3 fibroblast in a dose dependent manner in vitro[6]. EGF is a 6,000 Da polypeptide hormone produced by glands of the gastrointestinal tract, namely the salivary and Brunner’s glands. It appears to play a crucial role in major normal cellular processes such as proliferation, differentiation and development[14]. It may offer a rationale for the medicinal use of edible bird’s nest in ageing resistance. Since the receptor for EGF is highly expressed in a number of solid tumors, including breast, head-and-neck, non-small-cell lung, renal, ovarian and colon cancer[15], people are worried about a possibility to induce tumor progression and to resist chemotherapy/radiation treatment in tumor cells; in consequence, suggest that cancer patients should avoid edible bird’s nest. In fact, there is no evidence supporting this suggestion. Currently we have evaluated the effects of aqueous extract of edible bird’s nest on the viability on two human cancer cell lines, human breast cancer MCF-7 (ATCC HTB-22) and human liver cancer HepG2 (ATCC HB-8065). There was no observable effect on cell viability when comparing with the control group (unpublished data).
In 1994, a research team in China, evaluated the pharmacological effects of edible bird’s nest and pearl powder containing formulation. The formulation was demonstrated to have immunoenhancing effects by elevating DNA synthesis of T-lymphacytes and circulating immunoglobulin M content in mice. In addition, the formulation also showed ageing retardation by increasing the level of superoxide dimutase[16]. However, the study did not explore whether the effects came from either edible bird’s nest, pearl powder or both.
Further Studies
Edible bird’s nest has been used for several hundred years. Its usage is based mainly on historical, anecdotal and observational reports of its benefit. Scientific evidence for its efficacy is still limited. The putative health benefits such as resisting ageing and improving immunity of edible bird’s nest may be linked, at least in part, to EGF-like activity and mitogenic factor. However, there may be other mechanisms involved. In addition, there may be additive, synergistic or antagonistic effects between different components of edible bird’s nest. Work is needed to establish health-related effects of edible bird’s nest, for example, through assessing biomarker response, isolating and identifying the active components and investigating their possible interaction. In Hong Kong, many people take edible bird’s nest regularly. It is worth establishing epidemiological study to measure relationship of consistent use of edible bird’s nest and its putative beneficial effects in human beings. For the large market of edible bird’s nest, developing a systematic method to identify the sources of edible bird’s nest and check the authenticity of its sample is, undoubtedly, indispensable.
Acknowledgements
The author is grateful to Imperial Bird’s Nest International Company Limited for providing intact bird’s nests and their photos. Special thanks go to Ms. Siu-Hung Tsui for editorial assistance.
References
[1] Lee, P.L., Clayton, D.H., Griffiths, R. & Page, R.D. (1996) Does behavior reflect phylogeny in swiftlets (Aves: Apodidae)? A test using cytochrome b mitochondrial DNA sequences. Proc Natl Acad Sci U S A. 93:7091(7096.
[2] Lau, A.S.M. & Melville, D.S. (1994) International Trade in Swiftlet Nests with Special Reference to Hong Kong (Traffic Inter-national, Cambridge, U.K.).
[3] O’Hara, M.A., Kiefer, D., Farrel, K. & Kemper, K. (1998) A review of 12 commonly used herbs. Arch Fam Med. 7:523(536.
[4] Craig, W.J. (1997) Health-promoting properties of common herbs. Am J Clin Nutr. 70:491S(499S. [5] Yuan, R. & Yuan, L. (2000) Traditional Chinese medicine: an approach to scientific proof and clinical validation. Pharm Therapeut. 86:191(198.
[6] Kong, Y.C., Keung, W.M., Yip, T.T., Ko, K.M., Tsao, S.W. & Ng, M.H. (1987) Evidence that epidermal growth factor is present in swiftlet’s (Collocalia) nest. Comp Biochem Physiol B. 87:221(226.
[7] Leung, C.Y. (2004) Three billions market competition for edible bird’s nest shops. Economic Digest. 1197:68(69.
[8] Sam, C.T., Tan, P.H. & Lim, C.H. (1991) Establishing the authenticity of edible bird’s Nest. ISFM Medicine Scientific Review. 3:1(4.
[9] Li, X., Xi, X. & Che, W. (2003) Analysis and assessment of quality in import-export bird nest. Guangzhou Food Science and Technology. 19:72 & 89.
[10] Huang, H, Xi, X., Chen, W. & Chen, J. (2003) Determination of content of bird nest by spectrophotometer. Guangzhou Food Science and Technology. 19:68.
[11] Kathan, R.I.I. & Weeks, D.I. (1969) Structure studies of collocalia mucoid. I. Carbohydrate and amino acid composition. Arch Biochem Biophys. 134:572(576.
[12] Colombo, J.P., Garcia-Rodenas, C., Guesry, P.R. & Rey, J. (2003) Potential effects of supplementation with amino acids, choline or sialic acid on cognitive development in young infants. Acta Paediatr Suppl. 92:42(46.
[13] Ng, M.H., Chan, K.H. & Kong, Y.C. (1986) Potentiation of mitogenic response by extracts of the swiftlet’s (Collocalia) nest. Biochem Int. 13:521(531.
[14] Yano, S., Kondo, K., Yamaguchi, M., Richmond, G., Hutchison, M., Wakeling, A., Averbuch, S. & Wadsworth, P. (2003) Distribution and function of EGFR in human tissue and the effect of EGFR tyrosine kinase inhibition. Anticancer Res. 23: 3639(3650.
[15] Herbst, R.S. & Langer, C.J. (2002) Epidermal growth factor receptors as a target for cancer treatment: The emerging role of IMC-C225 in the treatment of lung and head and neck cancer. Semin Oncol. 29:27(36.
[16] Zhang, M., Wang, D. & Wang, J. (1994) The effect of the ZHENZHU-YANWO extracts on animal function. Pharmaceutical Biotechnology. 1:49(51.
用燕窩製成的佳餚：鮮百合冰糖燕窩
July 18th, 2006
New Straits Times, Malaysia - Jul 12, 2006
13 Jul 2006
Chok Suat Ling and Himanshu Bhatt
The lucrative bird’s nest business has come under fire from people who claim it is a health hazard and a threat to heritage. But entrepreneurs say the industry is misunderstood and should be allowed to develop, write CHOK SUAT LING and HIMANSHU BHATT.
MANY owners of “swiftlet hotels” in the country are laughing all the way to the bank. But others are less amused.
Over the last few years, getting swiftlets to roost in converted buildings has become big business as entrepreneurs cash in on the strong demand for bird’s nests, mainly from Taiwan, China and Hong Kong.
The nests, made from the saliva of Aerodamus fuciphagus, are said to be excellent for the complexion and in promoting respiratory and gastric health.
The swiftlet uses its spit to string together small gauze-like nests which are the main ingredient of bird’s nest soup, a Chinese delicacy.
The “bird-houses” started flourishing in the 1990s. There are now an estimated 30,000 such “swiftlet hotels” in the country, although not all have been successful in attracting the birds.
With the retail price of bird’s nest ranging from RM4,000 to RM5,000 a kilo, depending on its quality, it is no wonder that entrepreneurs are willing to spend tens of thousands of ringgit to convert old, sometimes abandoned, buildings, into homes for swiftlets.
The buildings are fitted with humidifiers and stereo systems that play recorded bird-calls to lure the birds, which normally roost in isolated caves.
Badan Warisan Malaysia believes that while the economic arguments for a bird’s nest industry may be strong, the need to protect heritage architecture and ensure a healthy environment is stronger.
Its executive director, Elizabeth Cardosa, says converting a heritage building into a “bird-house” is not only inappropriate but has many other deleterious effects.
Special conditions have to be created to encourage swiftlets to nest in these old houses, such as boarding up windows and doors to keep out sunlight, with small openings high up on the walls for the birds to get in and out.
“In a closed environment, moisture accumulates and accelerates the decay of plaster, brick walls and timber ceilings,” Cardosa says.
“The rotting wood invites termite infestation. Bird droppings also hasten the destruction of building materials and the interior ornamentation and beautiful embellishments of heritage buildings.”
She says neighbouring houses would also be affected by droppings and the noise of recorded bird-calls.
“Eventually, residents will sell or rent their houses in the core heritage zones of Malacca and Penang. This will have a devastating effect on the development of cultural tourism.”
Wildlife and National Parks Department (Perhilitan) enforcement director Misliah Bashir says the department issues licences to “swiftlet hotel” owners to harvest the nests, “but owners must first get a licence for the premises from the local authority”.
Guidelines have been issued in the past two years to ensure that local authorities have a consistent policy for the industry.
The guidelines, among others, specify that bird-houses cannot be built in residential or business areas and should be at least 100 metres from human habitats. But Misliah admits enforcement is not easy as the premises are sometimes locked up when officers arrive.
She says the chances of swiftlets contracting bird flu is minimal, allaying one immediate public concern.
“They are non-migratory and do not share flying or roosting space with other birds. Swiftlets also do not have the same food and water sources as other birds.”
Malaysian Bird’s Nest Merchants Association president Lim Theam Siew notes that several sets of guidelines have been formulated by government agencies — the Housing and Local Government Ministry, Perhilitan, and the Science, Technology and Innovation Ministry. But Lim say they cannot effectively regulate the industry.
“They do not understand the industry,” he says. “Some of the guidelines are not practical and would make it impossible for us to conduct our business.
“For instance, one of the requirements for a ‘bird-house’ is a fire escape. But why is that necessary when the only occupants are birds?”
In a tour of a converted shoplot in Seremban recently, Lim pointed out several bird’s nests jutting out like half-moon balconies from thin wooden planks attached to the ceiling.
Lim says owners of these “birdhouses” ensure the cleanliness of their properties as this will give them high-quality nests.
He says the association, which has a well-established membership, should be allowed to regulate the industry.
“We have the experience and can educate operators on the proper way to set up and maintain ‘bird-houses’. We teach them how to keep their premises clean and to ensure the nests are collected only when the chicks leave.
“The association has also organised seminars with participants from Cambodia, the Philippines and Myanmar.
“The Government can help us by doing research. Universities can formulate courses on bird’s nests. We should not be talking about licensing and regulations, but how we can create awareness.”
Cardosa says Badan Warisan does not wish to “bring the industry down”.
“If it is a viable industry, they should receive the support of the Government. Our concerns relate to the conversion of heritage properties into bird-houses.”
She notes that in Thailand and Indonesia, “bird-houses” are constructed in padi fields and near coastal areas, which do not place pressure on the cultural and heritage environment.
“At the end of the day, the question is whether we want a town or neighbourhood filled with people, or one which is potentially a ghost town filled with birds,” she says.
Penang making noise over incessant din
GEORGE TOWN: Amid the din of busy Chulia Street, one can hear the cries of swiftlets as they fly around the roof of an old shophouse with its windows and doors tightly shut.
But the urban bird’s nest harvesting business that has boomed in George Town is coming under pressure from the Government.
On Dec 31 last year, the Penang Island Municipal Council (MPPP) imposed stringent regulations for all bird’s nest operators to apply for licences.
Most have applied, but many are unable to comply with the conditions, says Komtar assemblyman Lim Gim Soon.
One of these conditions is to keep the noise down. Sounds made by tweeter speakers to attract the swiftlets must be less than two decibels. This volume is not enough to draw as many birds as breeders would like.
Many are also unable to change their land-use status from residential to commercial. Most of the 200 breeders on Penang island are in the city and are operating in heritage buildings even though the MPPP forbids bird’s nests in places gazetted as heritage structures or zones.
Tengku Idaura Tengku Ibrahim’s family bought a terrace shophouse on the Armenian Street heritage enclave a few years ago when they kept getting calls from strangers wanting to rent the premises to be used as “swiftlet hotels”.
Although they declined, some of their neighbours did not.
“The nests are all inside the buildings behind the casement windows,” Idaura said. “They’ve shut them out from the outside world with planks.
“But you can hear them all the time. It’s such a nuisance.”
There is also the almost incessant noise of the electronic tweeters that are left on throughout the day to attract the birds.
Idaura is also concerned that over time bird droppings will mar the beautiful façade of the heritage buildings.
The Penang Heritage Trust has been receiving complaints from people living in the inner city, said its chairman Dr Choong Sim Poey.
“People buying houses in heritage areas are caught by surprise when they find there are bird breeders in the neighbourhood.”
July 18th, 2006
Minneapolis-St. Paul Star Tribune - Jul 12 12:14 PM
Q In early July, I noticed that house sparrows had moved into the nests of the cliff swallows on the west side of our building at work. Swallows occupied most of the nests through June, but after July 4, sparrows resided in most of them. Did the sparrows evict the swallows, or did the swallows have time to fledge their young, then abandon the nests?
By The Minnesota Ornithologists Union
Last update: July 12, 2006 – 1:38 PM
Q In early July, I noticed that house sparrows had moved into the nests of the cliff swallows on the west side of our building at work. Swallows occupied most of the nests through June, but after July 4, sparrows resided in most of them. Did the sparrows evict the swallows, or did the swallows have time to fledge their young, then abandon the nests?
A Because of the timing, it is difficult to say whether the nests were abandoned before the house sparrows moved in or the sparrows took over the nests.
Cliff swallows are a protected native species that begin breeding in May and breed into July. They have one or two broods.
House sparrows will use the nests of both cliff swallows and barn swallows. Sometimes house sparrows fight for the nests and kill the young cliff or barn swallows. Sometimes they move in after the young have fledged.
However, recent research suggests that house sparrows do significant damage to barn swallow nesting colonies. In Maryland, sparrows reduced the fledging success rate of one barn swallow colony by 45 percent.
Why birds form a mob
Q I’ve seen groups of crows or blackbirds dive-bomb a hawk. Why do they do that?
A The behavior, called mobbing, is very common among crows.
Crows mob hawks and owls because they perceive these birds to be a threat. And it’s true that hawks have been known to kill crows — sometimes even when being mobbed — by flipping over to strike out at an attacking crow with their powerful feet and talons. That’s why crows are careful to stay above and behind a hawk when mobbing.
Other birds that frequently chase or mob hawks are Eastern kingbirds, blue jays and red-winged blackbirds. Like crows, jays usually mob a hawk or owl with many loud attackers, while single kingbirds and blackbirds typically give chase one bird at a time. Even some small birds, such as chickadees and nuthatches, will mob owls to protect themselves and their young.
This column is prepared by Minnesota Ornithologists’ Union (MOU) members Mark Alt and Anthony Hertzel. To ask questions for this column, call 612-673-4363 and leave a brief message. Or e-mail birds@stribmail.com. Questions will be answered in the newspaper only. For information about the MOU write to: Minnesota Ornithologists’ Union, Bell Museum, 10 SE. Church St., Minneapolis, MN 55455.
July 18th, 2006
Pioneer Press - Jul 16 1:09 AM
BY JIM OLICHWIER
Pioneer Press
SPOT IT BARN SWALLOW
The barn swallow is an expert flier, spending much of the daylight hours in flight, moving at high speeds and catching insects on the wing. Its midair acrobatics are unmistakable as it turns and dips at high angles. The bird is almost constantly moving its wings, rarely gliding.
As the name suggests, the barn swallow often builds its nest in barns or near the top of buildings with overhangs, including under the roofs of houses. With its nest so close to people, the barn swallow sometimes will perceive humans as a threat. To deter any predator, real or imagined, from reaching its nest, the swallow takes swoops at high speeds until the chicks are out of danger. While the aggressive barn swallow sometimes comes close to hitting people, it usually misses.
Despite the occasional close call, the barn swallow is beneficial to have in a back yard, where it consumes large quantities of insects. Its constant flying burns a lot of energy, which requires it to eat every few minutes.
Over time, the barn swallow has evolved from building its nests on the sides of cliffs and caves to using, almost exclusively, manmade structures. The barn swallow has benefited from human interaction; the more houses and buildings there are, the more potential nesting spots.
The barn swallow nest is made of straw and mud and lined with feathers. To build it, the bird picks up small pieces of mud, works the mud into a pellet and flies it to the nest site. Some nest construction requires up to 1,000 trips.
The swallow returns to the same nest site every year, and its offspring often nest within 20 miles of where they were born.
The deep-forked tail of the barn swallow distinguishes it from other kinds of swallows. The tail is also important to females looking for mates. The longer, the better. Unpaired males may try to break up a breeding pair by killing their chicks. Such action usually wins a mate for the aggressor.
Jim Olichwier can be reached at jmolichwier@pioneerpress.com.
July 18th, 2006
davesgarden.com
One vendor has this plant for sale.
Family: Aspleniaceae
Genus: Asplenium (ass-PLEE-nee-um) (Info)
Species: nidus (NID-us) (Info)
Category:
Tropicals/Tender Perennials
Height:
12-18 in. (30-45 cm)
18-24 in. (45-60 cm)
24-36 in. (60-90 cm)
36-48 in. (90-120 cm)
4-6 ft. (1.2-1.8 m)
Spacing:
24-36 in. (60-90 cm)
36-48 in. (90-120 cm)
Hardiness:
USDA Zone 11: above 4.5° C (40° F)
Sun Exposure:
Light Shade
Danger:
N/A
Bloom Color:
Inconspicuous/none
Bloom Time:
N/A
Foliage:
Evergreen
Smooth-Textured
Shiny/Glossy-Textured
Other details:
Requires consistently moist soil; do not let dry out between waterings
Soil pH requirements:
5.1 to 5.5 (strongly acidic)
5.6 to 6.0 (acidic)
6.1 to 6.5 (mildly acidic)
6.6 to 7.5 (neutral)
Propagation Methods:
By dividing rhizomes, tubers, corms or bulbs (including offsets)
From seed; sow indoors before last frost
Seed Collecting:
Seed does not store well; sow as soon as possible
This plant has been said to grow in the following regions:
Castro Valley, California
Encino, California
Hayward, California
Spring Valley, California
Bartow, Florida
Boca Raton, Florida
Jacksonville, Florida
Kathleen, Florida
Maitland, Florida
Miami, Florida
Hana, Hawaii
Honomu, Hawaii
New Orleans, Louisiana
Lafayette, Tennessee
Dallas, Texas
July 18th, 2006