掺水量对生鲜牛奶电导率的影响规律

为了给快速检测掺水牛奶提供一种方法，以生鲜牛奶为对象，通过给牛奶中添加一定量自来水的方法制备了掺水量在0%～14.02%之间8 个不同掺水量的牛奶样品，测量了各样品在10～35 ℃之间6 个温度条件下的电导率；分析了掺水量以及牛奶温度对电导率的影响规律；建立了描述牛奶电导率与掺水量和温度的关系模型，并对模型的掺水量预测能力进行了检验。结果说明，电导率随着掺水量的增大线性减小，而随着温度的升高线性增大。可用二元一次模型描述电导率与掺水量和温度之间的关系，该模型的决定系数为0.998 1。根据牛奶温度和电导率计算得到的掺水量与实际掺水量的绝对误差为－2.15%～2.03%，平均绝对误差为－0.06%，表明该模型能精确地计算牛奶的掺水量。

Influence of Added Water on Conductivity of Fresh Raw Cow Milk

Adding water to fresh raw milk is a common method in producing adulterated milk. The goal of the present
study was to establish a method for rapidly detecting the added water in milk. For this purpose, milk samples with different
proportions of added water ranging from 0%–14.02% were prepared by adding tap water to fresh raw cow milk. The
conductivities of these milk samples were measured at six temperatures from 10 to 35 ℃. The influence of added water
content and temperature on conductivity was comprehensively analyzed to establish and verify the corresponding model.
The results showed that the conductivity of cow milk deceased linearly with increasing amount of added water but increased
linearly with increasing temperature. The linear equation in two variables, with a coefficient of determination of 0.998 1,
could be used to describe the relationship between conductivity and the amount of added water and temperature. The
absolute error between calculated measured values for the amount of added water in cow milk was −2.15%–2.03%, with an
average of −0.06%, indicating that the amount of added water could be calculated precisely using the model.