The majority of people consider milk to be a relatively simple substance. However, a lot goes into producing it, one of the world’s most popular drinks and base products. While humans may have been producing milk for centuries, today’s manufacturing methods are considerably more complex than those used by our ancestors.
Global milk facts
It’s estimated in 2018 around 500 million metric tons of milk were produced around the world, with the European Union accounting for the biggest share and the US coming some way behind in second.
The amount of milk produced per cow has been increasing steadily over the years, rising from 17,760 pounds in 1999 to 23,800 pounds per cow in 2020 – due in part to better feeding and manufacturing techniques.
Milk is used in the production of two other staple diet items – butter, cheese – as well as a variety of other milk-based products.
The milk production process
If you’ve ever wondered how milk gets from cow to bottle, below is a quick overview of the milk production process. As milk is a perishable product, most of these stages happen very quickly after initial collection.
Milk collection: Most farms use mechanical vacuum milking systems to milk their dairy cows twice a day. The raw milk is then passed through pipes (typically using a positive displacement blower) to pump the milk to a waiting tank where it is cooled before collection by a tank truck. These trucks visit the farms daily to collect the milk before it is transferred to a processing facility, again pumped through pipes from the trucks to another tank.
Separation: During processing, the milk is passed through a clarifier (normally a series of disks) to remove any debris, sediment or particles of bacteria. It is also separated so that the heavier milk fat can be detached from the lighter milk, which can then be used to make butter or skimmed milk respectively.
Fortifying: At this point, some processing plants may add extra vitamins to the milk – normally vitamin A or D.
Pasteurizing: Pasteurization is the stage people are most familiar with and makes the milk safe by killing bacteria. In most pasteurization processes the milk is passed through a pipe to allow for high-temperature, short-time (HTST) treatment. The milk is heated to 161’F (72’C) for 15 seconds – with the pipe being sized equally by length and diameter to ensure the full 15 seconds elapse from end to end.
Homogenization: The majority of milk is homogenized to reduce the size of the milk particles and stop fat separation, which would otherwise float to the surface as cream. This process requires forcing the milk through small pipes at very high pressure. Thereafter, the milk is cooled quickly to maintain taste.
Packaging: Once the above stages have been completed, the milk is fit for human consumption and packaged – normally into plastic bottles or card cartons. Each bottle is stamped with a ‘sell by’ date to protect consumers and avoid retailers selling out-of-date milk. These containers are then transported to supermarkets and other stores, ready for purchase by customers.