Skimming milk - Use of separators in dairies
Raw milk contains around 4% fat. To obtain skimmed milk, dairies carry out a skimming process in which separators have always played a dominant part. A distinction is made here between warm milk skimming and cold milk skimming.
Warm milk skimming separator
These separators can be used in warm or cold milk skimming. Higher throughputs at very good efficiencies are generally achieved with warm milk skimming. Skimming separators are also efficient in milk skimming because of gentle product handling and yield maximization. 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.
Cold milk skimming Separator
However, cold milk skimming is on the rise, especially in the USA, Mexico, Australia and New Zealand. This means lower energy consumption and thus reduced production costs for the dairy when compared with the previously usual skimming temperatures. 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.