How is the adulteration of milk with water detected?

The adulteration of milk with water is primarily detected by testing for a high freezing point. When water is added to milk, it increases the overall volume but dilutes the components of the milk, particularly fats and solids. This dilution affects the freezing point of the liquid.

Pure milk has a specific freezing point that is lower than that of pure water. When water is mixed with milk, the freezing point of the mixture rises, indicating potential adulteration. In fact, a higher freezing point suggests that the milk contains a higher proportion of water than is natural. Therefore, measuring the freezing point provides a reliable method for detecting water adulteration in milk.

The other options, while they may detect different quality aspects of milk, do not effectively indicate the presence of water. Changes in color, smell, or clarity can result from various factors unrelated to water addition, such as microbial activity or processing methods. Thus, these methods are not considered reliable tests for detecting water in milk.