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Things to know about Dairy Lidding

If you know one yoghurt lid, you know them all. We talked to Xavier Bonamour about why this is not the case and what the differences are. Bonamour is Head of Product Management Dairy at Constantia Flexibles and an extrusion coatings expert.


Constantia Flexibles: On the supermarket shelf, all yoghurt lids look almost exactly the same...

Xavier Bonamour: At first glance, this seems to be the case. Lids for dairy products are usually die cut aluminum lids with a seal layer that encloses the aluminum. The seal is heated in order to fasten the lid to the yoghurt container so that nothing drips out. Lids have been made this way for more than 50 years, but naturally the process has been improved and enhanced as well. Earlier, the sealing layer was made of different varnishes, today extrusion coating with plastic is the state-of-the-art technology.

Constantia Flexibles: Most people probably haven’t thought much about how a yoghurt lid is produced. Can you explain this to us?

Xavier Bonamour: The manufacturing process is used not only for yoghurt lids, but for approximately 2/3 of the dairy products that are packaged here; these include spread cheese, desserts, sour cream and whipping cream. The basis is very, very thin rolled aluminum. We at Constantia Flexibles also do this ourselves – we have state-of-the-art aluminum rolling mills in our Constantia Teich location in Austria.

Then the thinly-rolled aluminum is coated with the liquid plastic on highly-sensitive systems. Here we are talking about very thin coatings that are thinner than the average hair. At Constantia we have developed a special co-extrusion process that allows us to apply several coatings of different plastics simultaneously - this way, we can fulfil our customers’ requirements perfectly.

Later, the lid is printed and punched from the aluminum roll - in the size requested by the customer. In the dairy’s filling systems, this plastic layer is then heated slightly so that the lid adheres to the yoghurt cup.

Constantia Flexibles: Earlier you said that lacquers were used once upon a time and that today the trend is toward plastics. What are the advantages here?

Xavier Bonamour: On the one hand, this is due to changed laws relating to foodstuffs; on the other hand, to the fact that new products also present new challenges for packaging. We started with co-extrusion technology in approximately 2002 when a big spread cheese manufacturer expanded its product line and determined that its paprika and tomato spreads were more aggressive and required greater resistance to corrosion. The extrusion process is ideal for this - it offers better protection against corrosion, it is solvent-free, behaves more neutrally overall with respect to foodstuffs and the cups can be sealed at a lower temperature. This saves on electricity for the filling system.

Last but not least, the co-extrusion process also allows us to work with thinner aluminum. A good example is our innovation “Die Cut 2020” lid ( Here, we can achieve material savings of up to 50%. This spares resources and makes the process more cost-effective for our customers.

You can compare this development and innovation step to the electric car revolution. The look and essential functions are identical to those of the usual yoghurt lid - however the long-term CO2 and material savings and the quiet, gentle opening behavior is not apparent to end consumers at first glance.

Constantia Flexibles: What is important when you are developing a new yoghurt lid with your customers?

Xavier Bonamour: Naturally it is important that the lid be easy to remove and that it does not tear. Furthermore, it must be possible to print it in perfect quality - for this is where the manufacturer presents their brand. And finally, all specifications of the food laws must be adhered to, especially those relating to protection and barrier properties.

Constantia Flexibles: One final question - can you still stand neutrally in front of the refrigerator case or do you automatically examine the various packaging?

Xavier Bonamour:  Of course my view is always biased, especially for goods abroad. My purchasing experiences are probably much different than consumers who do not share my profession and training. I like to shop …