How Proteins From Milk Are Made

The process of manufacturing the strong inside milk.

What distinguishes most proteins from milk from alternatives is that most are manufactured within miles of milk collection, often times in the same plant as where cheese is made (in the case of whey proteins made from cheese whey, for example).

What is very unique about proteins from milk is also the simplicity of the process, essentially just using a series of filters and pressure. Extracting proteins from milk, as opposed to alternative proteins, does not require the addition of artificial chemicals or harsh treatments. The natural size of the proteins is the very simple basis of the separation process.

Very low waste, high yields

Extracting proteins from milk is a low-waste process: 100% of milk is edible. This compares with the yield from other sources which may be less than 35%.

Few processing steps, local manufacturing, and modern filtration methods which guarantee very high yields, all contribute to the sustainability of these ingredients. 

The production, filtration and drying methods used by manufacturers are, nevertheless, highly sophisticated and controlled to ensure production consistency, excellent taste, high purity and excellent safety.

With proteins from milk appearing in so many different products, it is important to understand the process that takes the proteins from their source (milk) to the final form (powder, shake, drink or bar). Both whey and milk protein ingredients can be found in isolate and concentrate form. Casein is typically found in isolate form (~100% protein).

Concentrates

To make protein from milk concentrate, whole milk is first separated into cream and skim milk. The skim milk is pasteurized, then fractionated using ultrafiltration to make a skim concentrate that is lactose-reduced. 

This process naturally separates milk components according to their molecular size. Milk then passes through a membrane that allows some of the lactose, minerals and water to cross through. The casein and whey proteins, however, do not pass through the membrane due to their larger molecular size and are therefore concentrated. The proteins, lactose and minerals that do not go through the membrane are then spray dried to form a powder.

The process does not require harsh chemicals to extract the protein or remove anti-nutrients, which are simply not present in milk.

A similar process is applied to sweet whey (co-product of cheese manufacture) to obtain whey protein concentrate.

Isolates

Protein isolates are typically at least 90% protein, and contain very low levels of lactose.

Two separation methods are widely used for whey protein isolates. One method utilizes ion exchangers which extract whey protein from the whey stream (usually a co-product of cheese manufacture) according to the surface charge characteristics of the molecule.

The second method, membrane filtration, typically a combination of microfiltration and ultrafiltration, uses molecular size as the basis for separating components from the whey stream. In the process, simple pressure is applied across a membrane surface which forces smaller molecules through the membrane while larger molecules are retained.

Both methods yield a very high protein to non-protein product ratio.

Micellar casein and milk whey (“native” whey)

These ingredients are made directly from milk.

These concentrated milk protein products are produced using microfiltration of skim milk, which modifies the casein-to-whey protein ratio compared to that found in milk. The casein-to-whey protein ratio typically ranges between 82:18 and 95:5 for commercially available micellar casein products. Micellar casein is an ingredient most often found in sports and nutrition products.

The whey-enriched stream alternatively is called milk whey or “native” whey. This ingredient is also used in sports products and has potential in infant nutrition. It can be found in blends of whey proteins as well.

Casein and caseinates

Casein (acid) is obtained by coagulating skim milk, followed by separating, washing and drying steps. Rennet casein, an ingredient used in some cheeses, is made using enzymes. To facilitate applications in food products and drinks, casein may be further processed into caseinates (sodium, calcium, etc.).  Caseinates are found in a myriad of products where they act as natural emulsifiers, provide body and “creaminess.” Because they are lactose-free, caseinates are often used in non-dairy creamers, for example.

Milk powders

Milk powders are simply made from whole or skim milk, concentrated by evaporation, then spray dried. They are used worldwide as an ingredient in all food categories, and can be used when fluid milk is not available, or to fortify products for nutritional or functional reasons.