To make sure consumers receive milk that is of a consistent quality and taste, some fresh-milk companies standardise the protein levels. And they do this by using permeate in some milk types.

So what is permeate?

It is the name given to the milk-sugar (lactose) and minerals part of whole milk.

It is created when the original milk is put through an ultra-filtration process as part of overall milk processing. Fresh skim milk is put through an ultra-fine filter to separate the lactose, soluble minerals, and vitamins from the proteins and insoluble minerals. The lactose, vitamins, and minerals which filter through are known as permeate. It is this lactose-rich stream that is added back to milk to ensure the protein level – the taste – is consistent.

Dairy processors may adjust these components to produce a variety of different types of milk (for example, low fat, high calcium, no fat) to meet consumer demands. New Zealand has stringent food safety laws, and so these adjustments must be consistent with our food regulations.

The composition of milk is governed by the Food Standards Australia New Zealand (FSANZ) Food Standards Code, which ensures consumers purchase nutritionally consistent, high quality and safe products. This Code allows processors to adjust the components of milk delivered from farms, when necessary, to produce a wide variety of nutritionally consistent and safe products.

The key reason some dairy companies add permeate is to ensure consistency in taste right through the year.  The re-introduction of permeate in milk – essentially adding milk to milk – is a regular practice by some fresh-milk processors to ensure that consistency.