About swallow nest, swiftlet, edible bird’s nest

THE COMPOSITION OF CHINESE EDIBLE BIRDS’ NESTS AND THE NATURE OF THEIR PROTEINS.*

jbc.org
BY CHI CHE WANG. (Prom the Nelson Morris Institde for Medical Research, Michael Reese Hospital, Chicago.) (Received for publication, September 26, 1921.) Appearance and Origin. The edible birds’ nests are gelatinous substances produced by certain swifts, the Collacalia, natives of Malaya (1) and Ceylon. The nests, constructed in caves on the seashore, are collected while they are still moist and made into various shapes. The lowest grade is sold in the form of coarse powder. The higher the grade, the whiter the color and fewer the feathers and twigs. Owing to their high price, their use is limited to a delicacy at the feasts of the wealthy and a food for convalescents and the aged. The source from which the birds make the nests has been uncertain. Green (2) gives three suggestions: in the algas found in caves where the swifts make their nests, fish spawn, or a secretion from the swifts them- selves. The algss theory is disproved by the lack of vegetable cells shown by microscopic examinat.ion of the nests. The secretion theory is believed by most of the natives and has the support of Home (3) and Bernstein (4). The latter author found in the birds two large salivary glands which se- creted much viscous mucus. The observation given in this paper shows that the nests consist largely of a mucin-like substance and, therefore, is in accord with the latter hypothesis. by on August 15, www.jbc.org Downloaded from Review of Literature. The literature on the subject is limited. Descriptive statements con- cerning chiefly the occurrence and appearance of the nest may be found in Encyclopedias, China year books, and some semiscientific articles written during the early part of the 19th century. Green (2) and Krukenberg (5) are the first to give a report of a scientific study of the nest. Their work * The work reported in this article was conducted at the Nutrition Laboratory, Department of Home Economics, University of Chicago. It forms part of the thesis submitted in partial fulfillment of the require- ments for the degree of Doctor of Philosophy in the University of Chicago. Proteins of Edible Birds’ Nests covers the solubilities, the response to protein tests, and some observa- tions on hydrolysis products. Their results prove that the birds’ nest contains both the carbohydrate and the protein radicle, belonging to the class of mucin-like substances, the glycoproteins. Scope of the Present Work. The present work covers the study of the general properties, the chemical composition, the artificial digestion, the carbohy- drate radicle, and the biological value of the proteins. Compari- son is made with other work on mucin, especially Lothrop’s, Mtiller’s, and Levene’s. The material used for this work was supplied by the Hoo Loong Edible Birds’ Nest Store, Chicago, which imported it directly from China. It was of the highest grade, having somewhat the appearance of agar-agar, but it was extremely crisp and had tiny feathers interwoven with the mucilaginous material. For quantitative *analysis, the material was ground and sifted. On sifting, most of the feathers cling together and may be removed, but some go through the sieve xo that it is difhcult to. obtain a pure sample. Downloaded fro General Properties. A sample boiled in distilled water for 3 hours and left there for several days, swells like a piece of sponge, but shows no tendency to dissolve. The filtrate responds to neither protein nor carbo- hydrate tests. 5 per cent sodium hydroxide dissolves it on standing 2 hours in the cold. The colorless solution responds to Millon’s, the biuret, xanthoproteic, and Hopkins-Cole tests. The last reaction shows only faintly. It also has a slight reducing power with Fehling’s reagent. A dilute acid, such as 3 per cent hydrochloric acid, dissolves the birds’ nests only on heating. The solution acquires a purplish brown color, gives both protein and carbohydrate tests, and has a strong reducing action. So far the properties agree with those reported by Green (2) in every respect except that he found the nest insoluble in dilute sodium hydroxide in the cold. They also agree with the commonly recognized properties of mucin. by on August 15, 2006 ww.jbc.org C. C. Wang Chemical Analysis. 431 Samples between 1.5 to 2 gm. were taken for the determination of moisture and ash. Neumann’s method given in Mathews (6) was used for the estimation of phosphorus, and Denis’s method (7) for that of sulfur. An attempt was made to determine the ether-soluble substance, but the results were too small to be of significance, only 0.3 per cent. The estimation of total nitrogen by the Kjeldahl-Gunning method was made on samples treated in three different ways: (1) original birds’ nest, (2) ground birds’ nest with feathers partially removed, and (3) a sample hydro- lyzed for 132 hours in 20 per cent hydrochloric acid. Results are given in Table I. The total ash, 2.51, is almost seven times as high as that of submaxillary mucin, 0.37 per cent,’ reported by Lothrop (8). This high percentage of ash shows that the birds’ nest is not a pure mucin, but more probably dried saliva. Of the total ash 29.48 per cent is insoluble in water, but none insoluble in acid. Hence no sandy material is present. The sulfur content, 1.10 per cent, is in agreement with the figures given by Muller (9) for salivary mucin, 1.40 per cent, but it is higher than that reported by Lothrop (8), 0.55 per cent. The 006 432 Proteins of Edible Birds’ Nests discrepancy may be due to the different methods used or in case of birds’ nests, the presence of feathers. The phosphorus, 0.035 per cent, is too small to be of any significance. The different values for nitrogen found in birds’ nests treated in three different ways may be explained by the variation in the feathers present. The original sample containing the most feathers, had the lowest figure, 8.78 per cent, while that hydrolyzed with the least feathers, the highest or 10.29 per cent. The ground and sifted sample gave 9.15 per cent. Some feathers were re- moved during grinding and sifting, but more of them separated out by clinging to the walls of the vessel on hydrolysis. They could then be easily removed. The percentage of nitrogen of the hydrolyzed material, 10.29, agrees with the value given by Muller (9) for salivary mucin, 10.70 for total nitrogen but it is lower than that reported by Lothrop (8), 12.49 per cent. DowArtijicial Digestion. Artificial digestion experiments carried out in comparison with hard boiled egg white showed that the birds’ nests were digested by both pepsin hydrochloric acid and trypsin though not so quickly as the egg. The speed of digestion was determined by Sorensen’s titration (6). Comparison was made of the increase during 24 hours in the volume of 0.1 N sodium hydroxide for titrating 25 cc. of the peptic digest. Results were expressed in cc. per gm. of nitrogen in the material acted upon. For the birds’ nests in a typical experiment this value was 9:60 cc. and for the egg white 15.47 cc. Similarly, the increase of 0.1 N hydrochloric acid to titrate the tryptic digest was 19.02 cc. for the birds’ nests and 38.75 cc. for the egg white. The percentage of carbohydrate in the hydrolyzed birds’ nests could not be found with accuracy. Efforts using Benedict’s (10) Method 2 failed to give concordant results. The material was prepared in the following manner: 1 gm. of the ground and sifted nests was dissolved in a small amount of concentrated hydrochloric acid by standing over night. It was then diluted with distilled water to make a 5 per cent acid solution and boiled with a reflux condenser for 13 hours. The hydrolyzed mixture was treated with phosphotungstic acid, filtered, and the fltrate was made up to a definite volume. by on August 15, 2006 www.jbc.org ed from

Add comment August 16th, 2006

Bird’s nest soup

mirabilis.ca
From the Globe and Mail, Soup good, bad for you.

Bird’s nest soup — maybe that should be bird spit soup — seems to be both unexpectedly healthy and potentially harmful for those who relish its exotic taste.

A chemical analysis by Massimo Marcone of the University of Guelph of several edible nests made by the swiftlet, a small swallow native to East Asia, turned up a protein similar to that found in eggs. The protein is in the nest because the swiftlets weave a new home yearly, not out of sticks or straw but their own saliva.

Marcone argues that the existence of an egg-like protein would explain the mysterious occurrence of a severe allergy attack among some who dine on bird’s nest soup. Indeed, surveys in Singapore have found that the soup is the leading food allergy there.

However, the positive news for the non-allergic is that the same egg protein has been shown to have antibiotic properties. This would account for the legendary health properties of bird’s nest soup, if not quite medicinally justify its price of upwards of $10,000 a kilogram.

Add comment August 16th, 2006

Unexpected birds seen throughout the region

Corpus Christi Caller
8/12/2006
Probably because of the climactic change, some unexpected birds have turned up here this summer. I consider the little titmouse calling in my neighborhood somewhat out of place.

Several hooded orioles have been seen at feeders and therefore probably nested. One at the home of Erwin Becker, off Ennis Joslin Road, has been there for several summers.

Another, here for at least the second time, is at the feeder of Sharie Del Rio on Paloma. Another, probably a pair, has been seen nipping at the feeder on the porch of Jerry and Elizabeth Susser, on Wilshire Place.

Hummingbirds have continued to be present all summer this year. The rubythroated mostly have moved on, but there are black-chinned and buff-bellied, probably nesting. I leave one feeder up all year, filled with homemade syrup (one cup of sugar to four cups of water, brought to a boil). Never use food coloring. It is not good for birds.

I spoke with a man who lives near Lake Corpus Christi about a bird who talks to him at night. It calls from far away and when he answers, it calls again, closer.

We figured the bird probably is a goatsucker, a pauraque, a South Texas special. One was found nesting at a cemetery near Hilltop, across Leopard. The nest, on the ground, was discovered by Mary Maull as she hunted for butterflies.

These nocturnal birds call at dusk. I have seen them on Christmas counts on a road near Blucher Park, and also have heard them from there. The field guide describes their call as “purrrweear!” Their eyes glow red in darkness. The first I saw were at Welder Wildlife Refuge near Sinton.

Nesting season is the most dangerous time for birds. Some birds feel close and comfortable with humans, others don’t. I often hear of mourning doves nesting in hanging baskets on porches. Cardinals occasionally pick this spot, too.

If a bird nests on your porch, and you feel that way, try to remember that nesting season is short. Nests, however, sometimes are used for successive clutches. Doves fledge at 15 days and northern cardinals leave the nest between nine and 11 days.

Sometimes baby birds fall from the nest or end up on the ground when they are learning to fly. If this happens, replace the chick in the nest if possible; if not, put the chick in a box back in the tree.

Babies raised by parents have a much better chance at life. If you must take care of them, place them in a cardboard box with a partial lid.

Don’t try to feed a solid diet, instead give warm milk with a bit of sugar added from a medicine dropper as a starter. When you are sure the bird can swallow, start feeding very small bits of solid food, at intervals of a few minutes.

Very lean, raw ground beef is the basic food. To the meat, the following may be added: hard-boiled egg yolk mixed with baby cereal and milk or water to a consistency that may be picked up on the end of a toothpick. Some birds like and eat fruit, scraped raw apple, banana or a mashed grape. Some will eat mashed peanuts or sunflower seeds. No bird caregiver is available in Corpus Christi now.

Kris Meeks, a young woman who works in the office at Executive House Condominiums, has successfully raised a white-winged dove this year. If you undertake to care for a baby bird, you must have plenty of patience. Good luck.

Phyllis Yochem, a Corpus Christi resident, has studied birds in Texas since 1960.

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Add comment August 16th, 2006