Authenticity Determination of Bird’s Nests by Component Analyses
Date Issued
2006
Date
2006
Author(s)
Tung, Ching-hsin
DOI
zh-TW
Abstract
In order to gain insights into the qualities of bird’s nests found in local market nowadays, the components of various bird’s nest samples were used in this study to determine their authenticity.
Optical microscopy of various types of dried bird’s nest samples showed that they are colorless and transparent, and their shapes are rectangular or irregular fragments. The cross-section profile of bird’s nets has closely-spaced parallel texture, and some have densely-distributed tiny round holes or tiny granulates on their surface. Commercially available dried bird’s nests typically contain 52.1~63.4% of crude protein. Dried bird’s nest powder was easily hydrolyzed in acid. The protein hydrolysate were then derivatized with dansyl chloride, and analyzed by capillary eletrophoresis (CE).
Dried bird’s nest powder was dissolved in 10% tetramethyl- ammonium hydroxide solution, heated at 70℃, and analyzed by CE. Six characteristic peaks of major protein components of bird’s nest were found in the interval of 15-23 min migration time, whereas the adulterant pork skin and isinglass did not show these six peaks. Thus, CE analysis of protein profile was found to be an efficient technique to determine the bird’s nest authenticity.
Protein molecular weight was analyzed by using SDS PAGE, where gels were stained by the Bio-safe Coomassie stain and PAS (periodic acid stain). There were found 6~7 bands in the SDS PAGE for bird’s nests; moreover, most of them were glycoproteins.
Trifluoroacetic acid was used to hydrolyze sialic acid, neutralsugars and aminosugars of bird’s nests, and then the hydrolysates were analyzed by high performance ion liquid chromatography with pulsed amperometric detector (HPAE-PAD). The results showed that the glycoproteins of bird’s nests contain 0.44% of fucose, 0.2% rhamnose, 4.2% galactosamine, 5.3% glucosamine, 5.0% galactose, 0.75% mannose and 11.4% N-acetylnuraminic acid(Neu5Ac). In this research, bird’s nest content of “bird’s nest in rock sugar syrup” products was assessed by converting it into its sialic acid equivalent. The Neu5Ac/GalN ratio signifies quality of the “bird’s nest in rock sugar syrup” products. The Neu5Ac/GalN ratio of control bird’s nest was 2.3-3.0, while for 20 specimens of “bird’s nests in rock sugar syrup”, Neu5Ac/GalN ratios ranged from 0.03 to 3.0.
Subjects
燕窩
Type
thesis