Dai Yuwei, Cao Jie, Zhang Yu, He Feng, Jiang Lin
School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China.
J AOAC Int. 2022 Mar 15;105(2):567-575. doi: 10.1093/jaoacint/qsab096.
As a traditional Chinese health food, edible bird's nest (EBN) has high medicinal value, which is mostly attributed to the high content of sialic acid (SA). SA mainly exists in protein-bound, oligosaccharide-bound, and free forms and the binding forms of SA are closely related to the functions of EBN.
To establish a simple but robust method to distinguish and determinate the free and oligosaccharide-bound SA content and the protein-bound SA content, and investigate the changes to SA binding states in EBN during different processing.
Protein-bound SA in EBN was separated from other forms of SA by trichloroacetic acid precipitation, and SA content was determined by HPLC. The effects of stewing conditions on the distribution of SA in EBN were investigated and response surface methodology was used to explore the optimal conditions for enzymatic extraction of free and oligosaccharide-bound SA from EBN.
The average recoveries of free and oligosaccharide-bound SA and protein-bound SA were 97.82-98.92% and 94.67-95.75%, respectively. The content of free and oligosaccharide-bound SA in stewed EBN was proportional to the stewing temperature, stewing time, and liquid to material ratio, while that of protein-bound SA was inversely proportional to those factors. Through response surface analysis, we found that the optimum technological parameters were as follows: liquid to material ratio, 60:1; enzymolysis time, 2 h; enzyme dosage; 12 000 U/g (alkaline protease); pH, 11; enzymolysis temperature, 60°C.
This method can not only distinguish between free and oligosaccharide-bound SA and protein-bound SA effectively, but can also determine the contents of them. The results of the investigation on stewing conditions and response surface analysis can be used as the theoretical basis for further pharmacological research of EBN, and can also provide theoretical guidance for the development of EBN products.
A method for the determination of free and oligosaccharide-bound SA and protein-bound SA in EBN by HPLC was established, and the extraction process of free and oligosaccharide-bound SA was optimized.
作为一种传统的中国保健食品，燕窝具有很高的药用价值，这主要归因于其唾液酸（SA）含量高。SA主要以蛋白质结合型、寡糖结合型和游离型存在，SA的结合形式与燕窝的功能密切相关。
建立一种简便可靠的方法来区分和测定游离型和寡糖结合型SA含量以及蛋白质结合型SA含量，并研究不同加工过程中燕窝中SA结合状态的变化。
通过三氯乙酸沉淀将燕窝中的蛋白质结合型SA与其他形式的SA分离，并用高效液相色谱法测定SA含量。研究炖煮条件对燕窝中SA分布的影响，并采用响应面法探索从燕窝中酶解提取游离型和寡糖结合型SA的最佳条件。
游离型和寡糖结合型SA以及蛋白质结合型SA的平均回收率分别为97.82% - 98.92%和94.67% - 95.75%。炖煮燕窝中游离型和寡糖结合型SA的含量与炖煮温度、炖煮时间和液料比成正比，而蛋白质结合型SA的含量与这些因素成反比。通过响应面分析，我们发现最佳工艺参数如下：液料比60:1；酶解时间2小时；酶用量12000 U/g（碱性蛋白酶）；pH值11；酶解温度60℃。
该方法不仅能有效区分游离型和寡糖结合型SA以及蛋白质结合型SA，还能测定它们的含量。炖煮条件研究和响应面分析结果可为燕窝进一步的药理研究提供理论依据，也可为燕窝产品的开发提供理论指导。
建立了一种用高效液相色谱法测定燕窝中游离型和寡糖结合型SA以及蛋白质结合型SA的方法，并优化了游离型和寡糖结合型SA的提取工艺。
