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J Food Sci Technol (September 2016) 53(9):36023608 DOI 10.1007/s13197-016-2344-3
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Characterization of swiftlet edible bird nest, a mucin glycoprotein, and its adulterants by Raman microspectroscopy
Eric K. S. Shim1 Gleen F. Chandra1 S. Pedireddy1 Soo-Y. Lee1
Revised: 31 August 2016 / Accepted: 8 September 2016 / Published online: 20 September 2016 Association of Food Scientists & Technologists (India) 2016
Abstract Edible birds nest (EBN) is made from the glutinous salivary secretion of highly concentrated mucin glycoprotein by swiftlets (genus Aerodramus or Collocalia) native to the Indo-Pacic region. The unique Raman spectrum of EBN has vibrational lines that can be assigned to peptides and saccharides in the glycoprotein, and it can be used to screen for adulteration. The common edible adulterants classied into two types. Type I adulterants, such as sh bladder, pork skin, karaya gum, coralline seaweed, agar strips, and tremella fungus, were solids which adhered externally on the surface of the EBN cement. They can usually be detected with a microscope based on differences in the surface structure. Type II adulterants were water soluble substances such as saccha-rides (e.g., glucose, sucrose), polypeptides (e.g., hydro-lyzed collagen) and salts (e.g. monosodium glutamate) which can be readily soaked up by the EBN hydrogel when moist and adsorbed internally in the EBN cement matrix forming a composite upon drying, making them difcult to detect visually. The present study showed that Raman microspectroscopy offers a rapid, non-invasive, and label free technique to detect both Type I and II adulterants in EBN.
Keywords Edible birds nest Raman microspectroscopy
Mucin glycoprotein Adulterants Characterisation
Introduction
Raw white edible birds nest (EBN), also known as cubi-lose or nest cement, is a relatively strong, hardened, composite material made mainly of dried strands of amorphous mucin glycoprotein, secreted by male swiftlets of genus Aerodramus or Collocalia during the nesting and breeding season from a pair of sublingual glands under the tongue. The strands are bound together with feathers, and occasionally impregnated with tiny sand grains regurgitated from the birds gizzard, making a strong composite material to bear the weight of the nestlings. These swiftlets are native to the Indo-Pacic region and commonly found in South-East Asian countries, predominantly in Indonesia, Malaysia, Thailand and Vietnam. The raw...