紫黑色作物花色苷实验室定量检测方法研究

为了寻求快速、经济地测定自然界中紫黑色作物总花色苷含量的方法,利用酸性乙醇对黑元麦、茄子、葡萄3种不同作物进行花色苷提取,并采用pH示差法和差减法2种不同的实验室方法对3种样品总花色苷含量进行留样分析再测定。结果表明,黑元麦、葡萄采用pH示差法和差减法这2种测定方法的结果精确度和准确性没有显著性差异,且样品进行留样再检测时发现,2种样品测定结果之差的绝对值均小于测定结果质量不确定度,可以说明黑元麦、葡萄花色苷实验室定量检测pH示差法和差减法均适用。茄子采用pH示差法测定值相对标准偏差为2.20%,精确度明显好于差减法；从质控图看,茄子检出值出现1次连续4个点上升的情况,说明茄子皮利用差减法测定结果准确性差；从留样再检测结果可以看出,利用差减法测定2次结果之差的绝对值为0.023 mg/g,小于测定结果质量不确定度0.011 mg/g,说明茄子花色苷pH示差法检测结果可信赖,差减法检测存在问题。

Quantitative Determination of Anthocyanins from Purple and Black Crops

To find a rapid and economic method for the determination of total anthocyanins from purple and black crops in nature, the anthocyanins were extracted from three different crops of black wheat, eggplant and grape by using acidic ethanol. The total anthocyanin content from the three samples was determined by retentate analysis with pH differential method and subtraction method. The results showed that there was no significant difference in the accuracy of the results between the two methods using for black wheat and grapes. It was found that the absolute value of the difference between the results of the two methods was less than the uncertainty of quality determination when the two kinds of samples were re- tested, indicating that pH differential method and subtraction method were both applicable to laboratory quantitative detection of anthocyanin from black wheat and grapes. The relative standard deviation of eggplant measured by pH differential method was 2.20%, the precision was better than that of the subtractive method. There was a case of 4 consecutive points rise for the eggplant anthocyanins detected value from the quality control chart, showing that the accuracy of eggplant peel anthocyanin test results was poor by using subtraction method. The retesting showed that the absolute value of the difference between the two results obtained by the subtraction method was 0.023 mg/g, which was higher than the uncertainty of the measurement result 0.011 mg/g, indicating that the test results of anthocyanin from eggplant by pH differential method were reliable, but the test results by subtraction method had some problems.