Talk about edible bird’s nest throws up one unfamiliar word after another. They appear in our articles, and they appear in product descriptions. Sometimes the same word is used to mean different things by different writers. So here are the words we use, and the words you will meet elsewhere, set down together.
HOW WE WROTE THIS
The rules for this glossary
- We include both the words used in our articles and the words readers meet elsewhere
- We do not write about effects or benefits
- Figures carry their source and the conditions under which they were measured
- Where something is not known, we say it is not known
- We do not judge grades or gradings as better or worse
The bird, and where the nest is built
Swiftlet
The bird that builds the nests that are eaten. It is a separate lineage from the swallows of the order Passeriformes, and belongs to the order Apodiformes. Five species are confirmed in Malaysia (Hydrochous gigas / Collocalia esculenta / Cypsiurus balasiensis / Aerodramus maximus / Aerodramus fuciphagus). More detail is in The swiftlet as a bird — what is known, and what we have not yet checked.
Aerodramus fuciphagus
The principal species that builds the nests that are eaten. In 2022 the genome of this species was assembled (Kong et al. 2022).
Aerodramus maximus
A different species. Nests from caves include those of this species. When material circulating in East Kalimantan, Indonesia, as “feather nest” was examined genetically, it proved to be this species (Wang X et al. 2023).
Apus pacificus (fork-tailed swift)
Not a member of the genus Aerodramus. When material circulating in Huaiji, China, as “grass nest” was examined using the cytb gene, the nests proved to have been built by this bird (Wang X et al. 2023).
Birdhouse (house-farmed)
A building put up so that swiftlets will nest in it. The nests are built on boards and beams inside the building. The difference between harvesting here and harvesting in caves is covered in Is cave-harvested edible bird’s nest really safe? Heavy metals, and nitrite.
Cave-harvested
Nests taken from natural caves. That measured values split by origin is set out in The same “edible bird’s nest”, and yet the figures differ — numbers that split by origin.
A nest is used once
Once a nest has been harvested, the same nest is not used again.
Appearance and form
Guan yan / mao yan / cao yan
Names used to tell material apart in the market. They refer to the degree of feather inclusion or to origin, but the definitions are not standardised. There are reports that material circulating as “mao yan” and “cao yan”, when examined genetically, turned out to be a different species (Wang X et al. 2023). The name alone does not settle what is inside.
Yan zhan / yan tiao / yan sui
Names by the shape of the nest. Zhan is the original cup shape, tiao is broken into long strips, sui is fragmented. These are differences of shape, not of composition.
L, a and b values
Indices that express colour numerically: L is lightness, a is redness, b is yellowness. In a study across eight provinces of southern Thailand, the ranges for house-farmed (L 88.41 ± 1.00 / a 1.01 ± 0.04 / b 11.63 ± 1.01) and cave-harvested (L 81.31 ± 0.40 / a 1.91 ± 0.09 / b 17.45 ± 0.49) did not overlap (Chantakun et al. 2022).
Crystallinity
The proportion expressing how regularly the molecules in the fibre are arranged. In the same study: 35.52% house-farmed, 38.79% cave-harvested (Chantakun et al. 2022).
Bleaching
Whitening with chemical agents. We do not give figures for the amount of bleaching agent used or the concentrations detected, because we have not been able to obtain the full text of the original papers. We hold to that in Is “whiter is better” true? On bleaching, a processing step you cannot see as well.
Colouring
Adding colour. People in the field say there is a method of reddening with iron, but we have not yet confirmed it from primary sources.
What is inside
Salivary secretion
The material of the nest. It accounts for 70–80% of a dried nest. Covered in What is edible bird’s nest made of?.
Protein
The main component of the nest. The number of types identified, however, differs between papers. A study using the genome found 398 (Kong et al. 2022); a study of four samples without using a database found 37 (Wang X et al. 2023). The methods differ, so the two cannot simply be compared.
Glycoprotein
A protein with a sugar chain attached. The components of edible bird’s nest take this form. Covered in “Beyond sialic acid — what shows up when you look at edible bird’s nest as molecules”.
Sialic acid
A family of sugars that attach to the end of a sugar chain. Between “total” and “free”, the figure changes by an order of magnitude. More detail in “The ◯ in ‘it contains ◯% sialic acid’ changes with how you measure”.
Total sialic acid
The amount measured after cleaving the sugar chains with acid. In six samples of raw edible bird’s nest powder, 5.77–10.92% by weight (Poon & Sze 2023).
Free sialic acid
The amount measured without cleaving — only what is already loose. 135.04 ± 29.60 mg/kg (about 0.0135%) in 30 samples from Johor, and 95.55 ± 25.6 mg/kg in 23 samples from Kelantan (Khairunnisak et al. 2014). That is roughly 1/500 to 1/800 of the total.
Neu5Ac / Neu5Gc / KDN
Sialic acid is not a single substance. There is a report measuring these three separately (Wang M-H et al. 2024).
EGF (epidermal growth factor)
EGF protein itself has not been identified. The genome study states explicitly that EGF itself has not been identified in edible bird’s nest (Kong et al. 2022). What was found were proteins carrying Ca²⁺-binding EGF-like domains (fibrillin-1, protocadherin fat 4, coagulation factor X). A review, on the other hand, states “more than 3 mg of EGF per 1 g of protein”, and the literature conflicts. That conflict is covered in They say edible bird’s nest contains EGF. EGF itself has not been found.
Soluble solids
The fraction that dissolves and leaves the nest. 15.57 ± 0.10 g per 100 g house-farmed, 13.85 ± 0.06 g cave-harvested (Chantakun et al. 2022).
Safety, and the schemes
Washing
The step of rinsing in water to remove impurities. It is not a step common to all edible bird’s nest. There are also methods of removing with tweezers, shaping and drying, and how much is done differs completely from one processing plant to another. When figures are compared, it is necessary to check what was done to that sample. Covered in Has edible bird’s nest been washed?.
Nitrite and nitrate
Components present in the nest. Even in washed samples, house-farmed and cave-harvested differed (nitrite 5.7 vs 843.8 μg/g; nitrate 98.2 vs 36,999.4 μg/g; four samples each; Quek et al. 2015). This comparison, however, confounds species with region.
Heavy metals
Arsenic, mercury, lead, cadmium, tin and others. Across 44 nests in Indonesia, comparing before and after washing at the processing plant (about ten seconds in reverse-osmosis water), arsenic, lead, cadmium and tin fell significantly, while mercury fell but not significantly (Wahyuni et al. 2022).
Adulteration
Bulking material out by mixing something else in. Twelve substances are named in the literature (white fungus / jelly / fish maw / egg white / pork skin / karaya gum / red algae / agar / glucose / sucrose / hydrolysed marine collagen / monosodium glutamate). The bulking is put at 2–10% of final weight. How it is detected, and the limits of that, are set out in What has been mixed into edible bird’s nest — twelve substances confirmed in the literature, and the limits of telling.
MS 2334:2011
A Malaysian standard. It sets the ceiling on nitrite at 30 ppm or less (Yeo et al. 2021).
CAIQ-RZ-2015002
A Chinese standard. The ceiling on nitrite is likewise 30 ppm or less (Yeo et al. 2021).
BioNexus status
An accreditation of Malaysian companies. It is awarded by the Ministry of Finance and audited by the Bioeconomy Corporation. What is examined: whether the company owns the technology, whether its research has been verified, the amount invested, its research set-up, commercialisation and partners. It is not a scheme by which the state guarantees the effect of a material.
A required sialic acid content
No national standard contains one. What each country sets is a ceiling on what must not be present — nitrite, heavy metals, micro-organisms — not a floor on what should be (Yeo et al. 2021). So the claim that “more is better” has no backing in any standard.
In the kitchen
Soaking
Steeping a dried nest in water to reconstitute it. It is a different step, with a different purpose, from washing at the processing plant. Soaking the same dry weight does not give the same weight afterwards (weight after draining: 27.98 ± 1.32 g house-farmed, 30.78 ± 1.01 g cave-harvested; Chantakun et al. 2022). Covered in Soaking edible bird’s nest — what is happening while it soaks.
Soaking water
The water left after soaking. That soluble solids dissolve into it has been measured, but what they are has not been identified. About something whose contents are unknown, we will not write that you should drink it, nor that you should throw it away.
WHAT WE DON’T KNOW YET
What is still unclear
- Whether there is any industry-wide definition of guan yan, mao yan and cao yan. We have not yet found one
- We have not yet reached primary sources showing the reality of bleaching
- Primary sources for the claim that iron is used for colouring
- Public data measuring products circulating in Japan by a single consistent method
DISCLOSURE
About this page
TSUBAMEDIA is run by Japan Bansho Co., Ltd. That company handles edible bird’s nest as a business and is not a neutral third party. We do not compare other companies’ products or judge one against another. In describing research, we try not to go beyond what the original papers say. We do not sell products inside articles.
Every figure in this glossary is quoted from a published academic paper. None is a measurement of our own products. We will keep adding to these definitions as more articles are written.
SOURCES
- Kong HK, Chan Z, Yan CSW, Lo PY, Wong WT, Wong KH, Lo CLS. Revealing the species-specific genotype of the edible bird’s nest-producing swiftlet, Aerodramus fuciphagus. Food Research International. 2022;160:111670. doi:10.1016/j.foodres.2022.111670
- Wang X, Hu D, Liao F, Chen S, Meng Y, Dai J, Dong TTX, Lao Z, Yu L, Liang Y, Lai X, Tsim KWK, Li G. Comparative proteomic analysis of edible bird’s nest from different origins. Scientific Reports. 2023;13:15859. doi:10.1038/s41598-023-41851-6
- Chantakun K, Nilsuwan K, Sripradit A, Benjakul S. House and cave edible bird’s nest: Characteristics and quality of sterilised beverages containing the selected bird’s nest. International Journal of Food Science and Technology. 2022;57(4):2447-2458. doi:10.1111/ijfs.15606
- Quek MC, Chin NL, Yusof YA, Tan SW, Law CL. Preliminary nitrite, nitrate and colour analysis of Malaysian edible bird’s nest. Information Processing in Agriculture. 2015;2(1):1-5. doi:10.1016/j.inpa.2014.12.002
- Wahyuni S, Salim MN, Aliza D, Sabri M, Rahmi E, Hambal M. An investigation of heavy metals in edible bird’s nest from Indonesia. Veterinary World. 2022;15(2):509-516. doi:10.14202/vetworld.2022.509-516
- Poon PM-Y, Sze ET-P. Development of Method for Evaluation of Edible Bird’s Nest Content in Ready-to-Eat Beverages. Journal of AOAC INTERNATIONAL. 2023;106(4):1003-1009. doi:10.1093/jaoacint/qsad038
- Khairunnisak M, Marzura MR, Bing CH, Marni S, Norzela AM, Eddy AA. Preliminary study on free sialic acid content of edible bird nest from Johor and Kelantan. Malaysian Journal of Veterinary Research. 2014:9-14. ISSN 2180-3897
- Wang M-H, Wang Z-F, Yuan M, Yang C-G, Wang D-L, Wang S-Q. Changes in the Serum and Tissue Levels of Free and Conjugated Sialic Acids, Neu5Ac, Neu5Gc, and KDN in Mice after the Oral Administration of Edible Bird’s Nests: An LC–MS/MS Quantitative Analysis. Separations. 2024;11(4):107. doi:10.3390/separations11040107
- Yeo B-H, Tang T-K, Wong S-F, Tan C-P, Wang Y, Cheong L-Z, Lai O-M. Potential Residual Contaminants in Edible Bird’s Nest. Frontiers in Pharmacology. 2021;12:631136. doi:10.3389/fphar.2021.631136