Milk: from the field to the fridge

Everyone knows dairy products. In every possible variety. But hardly anyone knows exactly where and how they are produced. Be it yoghurt, drinking milk, cheese or curd – in every stage of production, innovative technologies ensure the production of high-quality food that is both tasty and healthy.

Source: Krones AG

The day gets off to a good start. Max opens the fridge and merrily gulps down some cold milk. It tastes great. He doesn’t give it another thought. And why not? Because milk is always available, everywhere. It’s always fresh and always tasty – despite the fact that milk is one of the most delicate foods: Milk perishes quickly and is susceptible to microorganisms.

This makes it the most strictly controlled food next to drinking water. The quality of milk is constantly checked and the production is strictly controlled throughout the entire process – right from milking the cow to filling the bottle. It is technology we have to thank for the fact that milk is the safest and cleanest food and can be found on our breakfast table in consistent quality and freshness. This technology, however, does not start in the dairy. It starts in the field. For it is precisely there where the quality of milk starts out: What you feed the cow is essential.

Agricultural drone on approaching

Is it a bird? Is it a plane? No, it’s a drone on its inspection flight. Equipped with a digital camera and controlled by mobile phone, it carries out a soil analysis. It checks whether there are mice in the field or whether the plants have plant lice infestations, the crop is broken or the soil moist in places.

Cows do not live under aseptic conditions, so milk production and manufacturing must take place in a contained and hygienic process. Source: Shutterstock, Olha Rohulya

Feeding, stroking, milking

Elsa is a cow and lives in farmer Hermann’s spacious barn. She can live her life the way she wants, and she feels at ease in the cozy of her herd. The farmer watches over her carefully. With a pedometer (a step counter) around her leg, an electronic sensor around her neck, a number chip on her ear and networked software, the livestock manager can tell, with a click, whether Elsa is moving, eating enough, whether she is in heat or sick or how much milk she is carrying.

Elsa the cow

This is Elsa the cow. She was born in farmer Hermann’s barn in 2014. The Friesian coated cow has a preference for eating strong, fresh green feed. And she likes a lot of it. She polishes off about 20 kilograms a day. But since she produces 10,000 liters of milk annually, she does need her food. Elsa is also rather enthusiastic when it comes to technology. That is why she was particularly pleased when farmer Hermann changed over from the milking stool to the milking robot. When she is not chewing or busy giving milk, Elsa likes to be massaged by a fully automated, fluffy neck brush.

The modern barn for the happy cow

Animal welfare is important because – in addition to the technology – it is a guarantee of the quality of the milk. The quality of the milk begins with the feeding of the cow. Good feed has an effect on the taste and the quality of the milk. Much like a home delivery service, a feeding robot places a fresh portion of hay and concentrated feed directly in front of Elsa’s hungry mouth. The blade of grass is still in her mouth. Elsa is still chewing while indulging herself in a massage. She gets stroked by an automated brush.

When robots do the milking

Elsa’s udder is now full. She wants to be milked and goes to the milking robot independently. A robotic arm extends out, finds her teats and checks whether they are clean. Hygiene is of top priority in milk production. If the teats are clean, the robot attaches the teat cups and pumps the milk directly into the milk tank via tubes. When the milk flow stops, the milking equipment is gently released from the teats.

Using its sensors the robot checks whether the teats are clean. Only then is the milking equipment attached. Source: Lely N.V.

From now on, the milk remains in a contained and hygienic cycle during the entire manufacturing and refining process. No air, nor human hand or other foreign bodies can come into contact – until Max opens the milk carton at the breakfast table.

Quality and hygiene right from the beginning

Already in the barn the milk is cooled down to 4 degrees Celsius. It must also be kept cool on the way to the dairy in order to avoid the multiplication of microorganisms. Even before the milk is pumped into the milk collection truck and the dairy takes the fresh delivery, the first quality samples are taken. Milk from sick cows or milk containing traces of antibiotics, for example, will not be accepted. The milk will only be processed when all quality standards are met.

See the herd – at the click of a button

An intelligently networked, digital command center keeps the livestock manager up-to-date on the animals’ state of health, their movement profile and their milk production.

High-tech milking

Untreated milk – so-called raw milk or attested milk – is rarely found these days. For good reason as the health and safety of the consumer ultimately are of uppermost importance. Scientifically-proven heat treatment processes turn dairy products into safe foods that are hygienically sound, healthy for human consumption and that have a long shelf-life.

Centrifuging, heating, cooling

From the tanker, the raw milk is pumped into a stainless steel tank and further cooled until processing. In order to kill harmful microorganisms, the milk must be treated. However, in the process it must not lose its nutrients and vitamins or its taste. This balancing act is quite a challenge. It requires a great deal of experience, excellent expertise and complex technology.

Determining the fat content

The milk is first passed from the tanks to the pre-heating unit in the heat exchanger via a feed tank, it is then subsequently purified of microorganisms and dirt particles in a centrifuge – the separator – and simultaneously separated into skim milk and cream. The centrifugal forces, which perform at around 6,000 revolutions per minute, float the heavy skim milk towards the outside and the light cream towards the inside. The milk is skimmed to a certain fat content: at least 3.5% fat in whole milk, 1.5% to 1.8% fat in low-fat milk and at the most 0.35% fat in skim milk.

What happens during homogenization?

After this procedure the milk is poured into the homogenizer. Under high pressure it is here forced through very fine jets. In this process the fat globules contained in the liquid are mechanically broken up and evenly distributed. This prevents a build-up of cream on the surface and also ensures a full-bodied taste as well as easier digestibility. If the fat content of the milk is adjusted in the separator and the milk homogenized, the milk is described as “standardized”.

The dairy: Quality and safety are top priorities

Sterilization

And now it gets hot: In the heat exchanger the milk is then heated with hot water or steam to turn it into long-life milk and to kill microorganisms. For this, there are different heat treatment processes with different temperatures and heating times. Depending on the desired type and shelf life, the milk is either pasteurized, ultra-heat treated, sterilized or filtered with ultra-fine membranes.

This demands a complex interaction of all electrical and mechanical components. A super-ordinate control system receives the signals of the individual components, processes them, and passes on corresponding control signals to the other components in the control loop. This interaction ensures that the right amount of milk at the correct temperature and the right pressure is always in the right place at the right time. Everything must be matched and coordinated, because even the smallest deviation leads to the milk getting damaged by too much or too little heat. And this will have a negative effect on the quality and shelf life of the milk.

After the heat treatment, the milk is rapidly cooled down again to 4 degrees. This temperature must be maintained throughout the cold chain in order to avoid further growth of micro-organisms.

Heat treatment processes of the milk

72°C- 75°C

At low heat

for 30 seconds for fresh milk which can last for a week.

104°C- 108°C

Microfiltration

for 1 to 2 seconds for ESL milk which can last for three weeks.

104°C- 127°C

At high heat

for 1 to 2 seconds for ESL milk which can last for three weeks.

135°C- 150°C

At ultra-high heat

for 1 to 4 seconds for long-life milk, which can last for up to eight weeks.

110°C- 120°C

Sterilization

for 10 to 30 minutes for sterilized milk which can last for up to a year.

Clean, hygienic, convenient: the milk carton. Source: Shutterstock, CroMary

Bottling, palletizing, enjoying

The final step and the final technical challenge – before the product is supplied to the supermarket – is the bottling of the milk. In a fully automated process, the printed and coated milk carton is formed into a package, filled and then sealed. On this final stretch, neither the milk nor the packaging shall be infested with microorganisms. Aseptic bottling systems create optimal hygienic conditions.

Hygiene is absolutely indispensable in food production. This applies to the product as much as to the machines and equipment components. The heat treatment of the milk mainly destroys harmful germs which spoil the milk. However, the heat treatment will not kill every single microorganism of any specific type. Even if this was technically feasible, the taste and valuable nutrients of the milk would suffer greatly. Therefore, there are always a few microorganisms left which can continue to multiply, so that the milk at some point becomes undrinkable or harmful to one’s health. It is therefore important that the machines and equipment components are designed in such a way that germs and contaminants do not stick and the equipment can be quickly and easily cleaned. Such a machine design is called hygienic design.

In a germ-free zone, the packaging is first sterilized on the inside by hydrogen peroxide for example, then the milk is poured into the package and finally hermetically sealed. The whole process takes place without sterilizing steam escaping or non-sterile external air entering the aseptic zone. Depending on the machine and the packaging format, up to 24,000 milk cartons can be filled per hour. Now it gets tranported to the retailer’s central warehouse and from there to the supermarket. And a short time later, Max will enjoy his milk at breakfast.

Always fresh. Always tasty. Max enjoys his milk. Source: Shutterstock, Rus S

“Innovative German mechanical and plant manufacturers ensure quality and safety – for freshness and great taste. Every single day.”

The Authors

Margret Menzel

Marketing and Communication Consultant

Since 2014, Margret Menzel has been responsible for the Marketing and Communications Department at VDMA Food Processing and Packaging Machinery Association. The range of this sector includes beverage machinery and dairy technology, meat processing machinery, bakery machinery, confectionery machinery, machinery and equipment for vegetable raw material processing, machines and equipment for the pharmaceutical and cosmetics industry as well as packaging machinery.

Christoph Götz

Press and Public Relations Consultant

Since 2008, Christoph Götz has been working for VDMA communicating exciting market and technology topics for the agricultural machinery and tractor industry in Germany and Europe. The current sector trends include intelligent networking solutions in the barn and in the field. As a global player, European agricultural machinery manufacturers serve the needs of farmers in around 150 markets worldwide.