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在羊乳中掺入牛乳也是乳品行业的一种掺假行为。由于牛乳中β-胡萝卜素含量远高于羊乳,本文建立了一种以β-胡萝卜素的含量作为特征指标用高效液相色谱法(HPLC)检测牛羊乳混掺的定量分析方法。乳样品皂化后,经石油醚提取、水洗浓缩后,使用岛津Shim-pack VP-ODS C18(4.6 mm×150 mm,5μm)色谱柱,以甲醇:乙腈:三氯甲烷(12:6:82,V/V/V)作为流动相洗脱,检测波长为450 nm。利用被检样纯牛羊乳中β-胡萝卜素含量变化范围,构建混掺比例线性曲线,实现定量分析。结果表明该方法的样品加标回收率为89.46%~98.19%,相对标准偏差为1.50%~2.79%。在主产季4~9月之间,牛、羊乳中β-胡萝卜素含量范围分别为0.08~0.13μg/g和1.9×10-3~2.2×10-3μg/g,线性相关系数在0.9958~0.9988范围内;盲样验证的相对误差在2.20%~4.75%之间。因此,以β-胡萝卜素为特征变量评价牛羊乳混掺比例的方法具有可行性。
Incorporation of milk in goat milk is also a form of adulteration in the dairy industry. Because the content of β-carotene in milk is much higher than that of goat milk, a quantitative method for the determination of bovine and sheep milk mixed by high performance liquid chromatography (HPLC) was established based on β-carotene content. After saponification of the milk sample, extraction with petroleum ether, concentration in water and washing with a Shimadzu Shim-pack VP-ODS C18 column (4.6 mm × 150 mm, 5 μm) and methanol: acetonitrile: chloroform , V / V / V) as the mobile phase, the detection wavelength was 450 nm. Using the range of β-carotene content in pure cow and sheep milk to be tested, a linear curve of mixing ratio was constructed to achieve quantitative analysis. The results showed that the spiked recoveries of this method were 89.46% ~ 98.19% with relative standard deviations of 1.50% ~ 2.79%. The content of β-carotene in cattle and goat milk was 0.08 ~ 0.13μg / g and 1.9 × 10-3 ~ 2.2 × 10-3μg / g in the main producing season from April to September, and the linear correlation coefficient was 0.9958 ~ 0.9988; The relative error of blind sample verification is between 2.20% ~ 4.75%. Therefore, the method of β-carotene as a characteristic variable to evaluate the proportion of bovine and sheep mixed with milk is feasible.