Raw milk contains around 4 percent fat. To obtain skimmed milk, dairies carry out a skimming process in which separators from GEA Westfalia Separator Group have always played a dominant part.
A distinction is made here between warm milk skimming at milk temperatures of 52 to 55 °C and cold milk skimming, which operates at milk temperatures of 4 to 20 °C. GEA Westfalia Separator Group supports both processes.
Higher throughputs at very good efficiencies are generally achieved with warm milk skimming. Recently, however, development of the innovative Westfalia Separator® procool system has provided an especially promising element in cold milk skimming. The GEA Westfalia Separator Group has also set new standards in gentle product handling and yield maximization with the Westfalia Separator® hyvol® proplus generation of skimming separators.
With Westfalia Separator® hyvol® proplus skimming separators, milk skimming can be optimized in a number of ways. The basis is Westfalia Separator® hyvol® separators whose hydrohermetic feed and very rapid ejection system have always stood for loss-minimized yield with gentle product handling. The Westfalia Separator® hyvol® separators have now been supplemented by the Westfalia Separator® proplus module, which is capable of obtaining valuable protein for further processing from the residual solids which have hitherto been unusable. These separators can be used in warm or cold milk skimming.
Mechanical skimming by centrifugal force is necessary to separate the raw milk into cream and skimmed milk. After separation, both are mixed together again in a certain ratio (depending on whether low-fat milk, fullfat milk or cream is to be produced) until the desired fat content has been perfectly set.
Most dairies work with warm milk skimming; the raw milk is first heated and then skimmed warm. Because of the higher temperature, there is a particularly significant difference in density between cream and skimmed milk and this has a positive impact on the skimming precision of a separator.
However, cold milk skimming is on the rise, especially in the USA, Mexico, Australia and New Zealand. Here, the operating temperature is between 4 and 20 °C. This means lower energy consumption and thus reduced production costs for the dairy when compared with the previously usual skimming temperatures of 52 to 55 °C.
However, this is far from being the only advantage. Milk which is kept warm for an extended period is more susceptible to microbiological contamination. Even if subsequent pasteurization guarantees a microbiologically perfect product, it is nevertheless attractive from a quality point of view to avoid from the outset any processes which could have a negative impact on the product. At cold temperatures, the growth of microorganisms is significantly reduced.
GEA Westfalia Separator Group supports cold milk skimming with the newly-developed Westfalia Separator® procool separator, the first cold milk centrifuge to use a belt drive and therefore consume less energy. The new generation of machines also provides the option of choosing between cold and warm. A dairy thus has the option of carrying out both cold and warm milk skimming with the same machine depending on what makes most sense for the final product in each case.