Development of Method for Evaluation of Edible Bird's Nest Content in Ready-to-Eat Beverages

Edible bird's nest (EBN) is one of the most valuable tonic Chinese foods, made from glutinous salivary secretion with highly concentrated mucin glycoprotein. For ease of consumption, manufacturers have marketed different ready-to-eat EBN products, in which the EBN content varies. This is the first study to analyze the EBN content in ready-to-eat beverages.

To determine the EBN content in ready-to-eat beverages by its active ingredient, N-acetylneuraminic acid (sialic acid).

Sialic acid in ready-to-eat beverages and raw EBN was extracted in sodium hydrogen sulfate solution, followed by derivatization using o-phenylenediamine dihydrochloride and determination using high-performance liquid chromatography (HPLC). Method precision, recovery of extraction, degradation of sialic acid due to cooking, and measurement uncertainty were evaluated.

The mean concentrations of raw EBN in different origins and colors ranged from 5.77 to 10.92%. Ten different brands of traditional ready-to-eat EBN beverages from the market were analyzed, in which estimated concentrations of EBN were diversified, ranging from 0.014 ± 0.010 to 0.66 ± 0.069% (w/w) (95% confidence level). The concentration of sialic acid was found to range from 11.4 to 527 mg/kg.

Based on the results, sialic acid content can provide a better estimation of the EBN content in traditional ready-to-eat beverages. Neither the selling price nor dried matter could be used as an indicator of the quality of the ready-to-eat EBN beverage among the samples obtained.

Sialic acid can be used as an indicator to estimate EBN content, where the sialic acid and EBN content in ready-to-eat beverages from the market were found to vary significantly.