海带中昆布素的荧光定量检测及提取工艺优化

Fluorescence quantitative detection and extraction process optimization of laminarin from kelp

针对昆布素检测技术的难点，利用昆布素与苯胺蓝能特异性结合的特点，采用荧光分光光度计建立了昆布素含量的荧光快速检测方法。实验结果表明：NaOH浓度对昆布素立体结构影响较大，在昆布素解旋过程中加入70μL 3mol／L的NaOH能使昆布素-苯胺蓝荧光复合物具有最大的荧光信号；通过三维荧光扫描，确定昆布素．苯胺蓝荧光复合物的最佳激发和发射波长分别为398nm和502nm，在此条件下昆布素-苯胺蓝荧光复合物浓度与其荧光值正相关（R^2=0．9994）；方法学分析表明：该测定方法具有较高的精密度（RSD为2．52％）和稳定性（RSD为2．09％），检测范围为20～80mg／L。基于所建立的昆布素含量快速检测方法，本文设计了有关提取温度、提取时间、pH以及乙醇浓度四个因素三个水平的正交试验对海带中昆布素的提取条件作了初步优化，结果表明：海带中昆布素的最佳提取条件是：置于稀盐酸（pH为1）溶液中于25℃下提取4h，90％乙醇沉淀。

Laminarin is a series of bioactive low-molecular weight glucan. Aiming at resolving the difficulty of laminarin quantification in kelp, a rapid analytical method based on aniline blue staining was established. Aniline blue could combine specifically to laminarin and form a fluorescent complex which could be detected by fluorospectrophotometer. The results show that the concentration of NaOH significantly influenced the three di- mensional structure of laminarin. The fluorescence intensity of laminarin-aniline blue complex reached the maxi- mum when 70 μL of 3 mol/L NaOH was added during the process of laminarin despiralization. The optimal excita- tion and emission wavelengths of the fluorescent complex were 398 nm and 502 nm respectively. A linear correla- tion between the concentration of the complex range from 20-80 mg/L and the fluorescent intensity was obtained （R2=0.9994）. The methodological study indicated that the repeatability and stability of this analytical method were 2.52% and 2.09% respectively. Using above laminarin quantitative method, we also studied the optimal extraction technique of laminarin through orthogonal experiment. The results show that the optimal condition is to keep kelp powder in hydrochloric acid （pH=l） solution for 4 hours at 25℃ and precipitate laminarin with 90% ethanol.