Control of the water content of dairy products—definition of limits, consideration of process variation, official use of autocontrol data

The control of the water content of dairy products is of considerable economic importance. Ideally, it should be possible to evaluate the water content of consignments, or even products, made within an extended time period. In the real world, official control results may often just allow statements on sample units. As the water content of many dairy products is adjusted to a certain level, determined by legislation, control results reflect process conditions and measurement uncertainty. Both sources of variation are to be taken into consideration when defining compliance with legal limits. On the other hand, it is hardly possible to cover these aspects by official analysis. Control authorities must have access to the autocontrol data of the producer. An adequate concept for future official controls includes the use of this information and regular checks of its reliability. Consequently, official control would focus on reliability checks rather than direct controls of the water content of dairy products. When controlling drinking milk, the relevant aspect is not the water content of this product but the percentage of added water. It can be determined by a comparison with the composition of raw milk used for drinking milk production. A statistical approach is required.