There are often comments around the addition of ‘permeate’ to milk as if to suggest it’s a foreign additive. Permeate is a natural by-product of milk processing.


Here are the facts:

Because milk is a natural product which comes straight from the cow, its composition can vary. The protein content in fresh milk varies according to the lactation and feed cycle of cows, and even where the farm is and the breed of cow. For example, protein levels in milk are higher in autumn and winter and lower in spring and summer. The taste of milk can be different depending on the levels of fat and protein in it.

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 slim 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 issue is that New Zealand consumers like consistency in taste. They like to know that the milk they are putting on their cornflakes and drinking in their flat whites in September will taste the same in May. This is what standardising milk is about, so consumers get exactly what they expect a brand to deliver in terms of taste and consistency.

The re-introduction of permeate in milk – essentially adding milk to milk – is a normal part of milk processing and regular practice by fresh-milk processors to ensure that consistency, and so people can continue to consume milk as part of a healthy and balanced diet.