基于β-胡萝卜素检测的牛羊乳混掺鉴别技术

Detection of Adulteration of Goat Milk with Cow Milk Based on β-Carotene Analysis

在羊乳中掺入牛乳也是乳品行业的一种掺假行为。由于牛乳中伊胡萝卜素含量远高于羊乳，本文建立了一种以伊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-packVP-ODSC18（4．6mm×150mm，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450nm。利用被检样纯牛羊乳中伊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、羊乳中伊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。

The fraudulent practice of substituting goat milk with cow milk is prevalent in the dairy industry. The level of β-carotene in cow milk is much higher than that in goat milk; hence, a quantitative analysis was established using high-performance liquid chromatography for the detection of adulteration of goat milk with cow milk, using the β-carotene level in the milk as a characteristic variable. Milk samples were saponified and extracted with petroleum ether, washed, and concentrated. Subsequently, the sample was eluted on a Shimadzu shim-pack VP-ODS C18 column （4.6 ×150 mm, 5μm） by using methanol-acetonitrile-chloroform as the mobile phase and a detection wavelength of 450 nm. The variation range of β-carotene in pure cow and goat milk was used to construct the mixing ratio linear curve to perform quantitative analysis. The results showed that the recovery rates of this method were between 89.46% and 98.19%, while the relative standard deviations were between 1.50% and 2.79%. During the main production season, from April to September, the range of β-carotene levels in pure cow milk and goat milk was 0.08-0.13 μg/g and 1.9×10^-3-2.2× 10^-3 μg/g, respectively. Linear correlation coefficients were between 0.9958 and 0.9988, whereas the relative errors of blind samples were between 2.20% and 4.75%. The results suggest that the method using β-carotene as a characteristic variable to evaluate the mixing ratio of cow milk in goat milk is feasible.