Milk doesn’t have a long shelf life. Once opened, a milk bottle can go off in a matter of hours if left unrefrigerated. And even then, milk barely lasts a week in the fridge before transforming into a smelly, unrecognisable substance.
Since humans started drinking milk, we’ve been looking for ways to improve it. Whether for taste, nutrients or preservation, humans have gone out of their way to outdo the natural materials found on earth.
One such method of extending its shelf life is evaporating fresh milk until it is a dry powder. Able to last in the cupboard for up to three years, manufacturers can also boost milk powder with improved levels of nutrition–more vitamins, more minerals and a flavour superior to the milk you buy from the grocery store.
Is powdered milk healthy? It sure is. But we want to share with you how milk powder is made and how it can make a difference in your life. Keep reading to learn more.
Where Does Powder Milk Come From?
It all starts with the humble cow. And a whole lot of them. Australia manufactures more than 220,000 tonnes of milk powder annually, a significant chunk of the nearly 9 billion litres of milk produced yearly, sourced from approximately 1.5 million dairy cows.
However, not all milk is created equal. Just as the Angus is the preferred breed for delicious steaks in Australia, there are also preferred breeds for milk worldwide. One such breed is the KiwiCross cow. Decedents of noble Jersey and Holstein-Friesian breed, the KiwiCross cow, is one of the most premium cattle breeds in the world, of which only 1 in 8 cows receive the seal of approval to ensure quality and flavour.
What’s particularly special about these cows is that they are 100% genetically verified A2 cows that produce only the A2 protein, not A1. The presence of the A1 protein in standard cow's milk is linked to the gastrointestinal discomfort many experiences after consuming dairy products.
These graze-free cows also have higher levels of CLA, benefiting immunity and bone health.
Using Powdered Milk
Milk powder is suitable for anyone over the age of three. A necessary ingredient for infant formula, milk powder is also used in confectionery (chocolate, caramel etc.) and baking. It’s also a mainstay for food aid supplies or wherever long shelf life is necessary.
But best of all, milk powder is a fantastic substitute for regular milk and is often boosted to be more nutritious, enjoyable and delicious. Some milk powder products go far beyond convention to transform and elevate dairy products from basic to exceptional. Milk powder isn’t just an alternative. It's a superior replacement.
The Benefits of Milk Powder
Milk is already an excellent source of nutrients–protein, vitamins A, D, and B12, riboflavin and minerals such as calcium, phosphorus, zinc, and iodine. Milk powder is often better because manufacturers can double all of the above, making this liquid gold even more nutritious and beneficial to your health.
Longer shelf life (up to three years in the cupboard)
More protein for strength
More calcium for bone health
More vitamins and minerals for optimal health
And if you choose milk powder boosted with probiotics, you’ll also enjoy a boost in your immune system. This combination can effectively enhance digestion and absorption of nutrients, including dairy protein, vitamins and mineral elements.
Commercialised Dried Milk Powder
Milk powder is a method of preservation that goes as far back as Marco Polo and his accounts of the Mongols using a sun-dried skim milk product as "a kind of paste". However, it wouldn’t be until 1802 that humans discovered the first modern production process for dried milk.
Invented by Russian doctor Osip Krichevsky, the process would be commercialised by Russian chemist M. Dirchoff in 1832, followed by two patents for dried milk powder in 1855 by T.S. Grimwade and a vacuum drying process in 1837 by William Newton.
How milk powder is made is incredibly simple and doesn’t differ much from modern production methods. In Dirchoff’s process, “fresh milk is slowly evaporated by a very gentle heat, till it is reduced to a dry powder, which is to be kept perfectly dry in a bottle, well stopped, for use”.
Preparing For Production
To make milk powder, you must first test the milk for acceptance, standardise the fat content, pasteurise it, separate skim milk from cream, preheat and then evaporate the remaining water. And that’s before you choose your drying method–spray drying, drum drying and freeze-drying.
Standardisation and Pasteurisation
Before milk powder can be produced, the milk must first be tested for acceptance, i.e. quality control. Once the milk is standardised to meet a ratio of fat and solid-not-fat in raw milk, it is heated quickly at a high temperature (pasteurisation) to eliminate harmful bacteria.
After pasteurisation, the milk is separated into skim milk and cream using a centrifugal cream separator, which can be added back in to produce whole milk powder, or used to make butter or anhydrous milk fat (clarified butter).
The standardised milk is then preheated to between 75 and 120°C for a specified time ranging from a few seconds to several minutes. Preheating the milk causes a controlled denaturation (modification of the molecular structure) of whey proteins. This process destroys bacteria, inactivates enzymes, generates natural antioxidants and imparts heat stability.
Before the final drying stage, milk is concentrated depending on the milk powder–9.0% total solids content for skim milk, 13% for whole milk, and up to 45-52% total solids. Milk is boiled under a vacuum at temperatures below 72 °C, removing the water as vapour. This vapour is then used to reheat the milk to remove more than 85% of the water.
Three Manufacturing Methods
The most common method for manufacturing milk powder is spray drying. This process atomises the milk into fine droplets, absorbing moisture with dry air, which is blown away and replaced with more dry air, continuing the extraction process until the milk is a dry powder.
Pasteurised milk is then concentrated into roughly 50% milk solids in an evaporator. The remaining concentration is sprayed into a heated chamber, evaporating the water instantly, leaving behind particles of powdered milk solids.
A thin film of milk is applied to the surface of a heated drum. The dried milk solids are then scraped off to produce powdered milk. Due to the increased temperature, drum drying does cause the milk powder to caramelise.
Also known as lyophilisation, freeze drying uses sublimation (converting solids into gas) to produce powdered milk. The use of cold temperatures also maintains the biological properties of the milk, allowing manufacturers to retain its nutritional value. Unfortunately, because of the energy required to freeze dry, this method of making powdered milk is not as widely used.
Homemade Milk Powder
Making milk powder at home is as simple as heating a large oven dish full of fresh milk.
* 1-litre full-cream milk
* Large oven dish
* Mortar and pestle, or
* Blender, or
* Airtight container
Pour room temperature milk into an oven dish.
Place the dish inside the oven and set it to the lowest temperature.
* 50-60ºC is ideal.
* Use fan-assist if possible, or leave the oven door ajar for evaporation.
Stir occasionally as the milk turns into a paste-like substance.
* Reduce the temperature if the paste begins to brown.
Remove paste from the oven dish and spread over baking paper. Return to the oven to complete the drying process.
Remove dried milk from the baking paper.
Grind into powder using a mortar and pestle, blender or grinder.
Store milk powder in an airtight container.