果蔬中总多酚和维生素C测定方法优化的研究

目的建立一种简单、准确地测定果蔬中总多酚和维生素C含量的方法。方法采用Oasis HLB固相萃取柱富集待测物质,用纯水洗脱回收水溶性干扰物质,用甲醇洗脱回收多酚类物质,加热水洗脱液除去其中的维生素C,优化福林酚比色法,测定总多酚和维生素C的含量。结果该方法的线性方程为Y=0.0118X+0.0045,R2=0.9989,确定福林酚比色法的条件为:在760 nm处测定,福林酚试剂:水(1:1),7.5%的Na2CO3溶液,温度为20~30℃,静置60 min。通过采用福林酚比色法分别测定原料提取液(RE)和水洗脱液(WE)中还原性物质的含量,取其差值作为样品总多酚含量。同时,测定加热处理水洗脱液(HWE)中还原性物质的含量,取其与WE测定结果的差值作为样品维生素C的含量。结论此方法简便实用、条件易满足,分析结果可靠,可应用于果蔬总多酚和维生素C含量的测定。

Study on optimized determination of total polyphenols and vitamin C

Objective To optimize a simple and accurate method for determination of total polyphenols and vitamin C in fruits and vegetables. Methods Substances were extracted by solid-phase extraction column and then the water soluble interference reducing-substances eluted by water, the polyphenols eluted by methanol. Then subtract the vitamin C from water extract by the method of heating. The total polyphenols and vitamin C were determinate by correcting Folin-Cioculteu assay. Results The linear equation of this method was Y=0.0118X+0.0045,R2= 0.9989.The condition of the Folin-Cioculteu colorimetry was confirmed, the maximum absorption wavelength is 760 nm,Folin-Cioculteu reagent concentration is 50% percent,7.5% Na2CO3 solution, room temperature stability, stewing 60 min. The recovery percents of polyphenols, 65%~99%were varied through extracting by solid-phase extraction column, the content of total polyphenols could not be determinate accurately. Therefore, this assay the content of reducing substances of raw extract and water extract were determinate by Folin-Cioculteu colorimetry, the total polyphenols content were assayed by subtracting the interfering reducing of water extract(WE)substances from the Folin-Cioculteu response of raw extract(RE).While the content of vitamin C was assayed by subtracting the Folin-Cioculteu response of heating water extraction from that of water extract(WE).Conclusion This method is simple and practical, the experiment condition is also satisfied easily, moreover the analysis results are reliable and that can be applied in the determination of total polyphenols and vitamin C.