advances in the uht Pasteurisation preservation method
There are two major ways in which the UHT Pasteurisation method has advanced since the 1860's when it was invented. There are technologically and packaging.
technological advancements - the pasteuriser
The piece of equipment used to pasteurise UHT milk, the pasteuriser, has changed significantly over the years. The earliest recorded pasteurising machine was created by Gustav Schneider in 1892. Over the years, many new pasteurisers were designed, and one of them was A. Jensen who created a new steam based pasteuriser in 1901. His pasteuriser was simple and nowhere near as complicated as the pasteurisers that are used today.
Nowadays, much more complicated and larger pasteurisers are used. This is due to technological advancements and a higher demand for UHT long life milk throughout the world. However, not all pasteurisers are the same. Some of them hold 25 litres of milk and some hold up to 1000 litres, all depending on whether or not they are used commercially or for smaller supplies. Also, due to many new healthy and safety laws, pasteurisers must meet a certain level of standards before they can be used.
packaging advancements- Tetra Pak "aspetic Packaging technology"
There is one company whose invention is responsible for the major advancements of UHT long life milk packaging, and that company is Tetra Pak. Tetra Pak are a Swedish based food packaging and processing company. 'Aseptic Packaging Technology' is Tetra Pak's packaging solution that they invented in 1961. Aseptic can be defined as "the process in which UHT milk and its package are sterilised separately and then combine and sealed under a sterilised atmosphere".
Aseptic packaging uses special techniques to sterilise the packages, machinery and environment in which the UHT long life milk is packaged in . This ensures that the UHT long life milk is protected against bacteria and the outside environment. To sterilise the machinery which will be used in the packaging process, hot air and steam and the combination of heat treatment with hydrogen peroxide, is used. Once this is done the packaging material must be sterilised. The steps used to do this are to first pass the packaged material through a hydrogen peroxide bath which is heated to 70 degrees Celsius for 6 seconds. Then, the hydrogen peroxide must be eliminated from the packaging by hot air. After these two sterilisation processes have taken place, the UHT long life milk can be successfully packaged in the sterilised containers.
But what exactly is the packaging made of that makes it so safe to use? Tetra Pak's packaging has many layers different materials that ensure the safe storage of the UHT long life milk. Paperboard which is made by carefully harvested trees, makes the package strong yet lightweight. To seal the UHT milk from any external moisture, thin layers of polyethylene are added. A thin layer of aluminium foil is also used to protect the UHT long life milk from light and oxygen.