How are pastry bags made?

When we reach for the bread products in the supermarket, we automatically reach for the bag. Perhaps we don’t even think about why it has a “window”, or why it’s not completely homogeneous. And certainly not how it is made. However, we’d love to tell you!

When you buy a bun, a baguette or a loaf of bread, you wouldn’t put it naked in the basket or even on the cash register tape to avoid contamination!

We also expect that no one will be allowed to take home a pizza bag or a chocolatey cocoa swirl with their bare hands. The packaging material we can choose for them is not your average nylon bag, but a bag with a really special structure.

It’s special because it has a window, i.e. a part that is transparent – so the cashier can quickly and hygienically (without touching it) see what and how much has been put in. The window, if you look closely at its structure, you can also see that it has been sprinkled with tiny holes. Why? This is to allow the bag to ventilate, because if you put hot jelly in it and close it, the moisture can cause the goods to fill up. The perforation of the window material is microperforation.

It is true that technically it is not really perforation, but rather micro-perforation is the process of piercing the material in several places, or more precisely, burning holes in the film.

This process is necessary because it creates a harder melt around the holes instead of the normal punching. This is so that the material does not weaken in the hole and cannot be torn out by the tip of the bun when it is inserted. Good packaging can also reduce food waste, as bread can be eaten for longer than without it.

Three interesting facts

1. What is a pouch window made of?

Most often made of polypropylene, which is plastic but fully recyclable! If you separate it from paper at home and put both: plastic and paper in your own bin, you have not harmed the environment! And don’t be scared of cellophane, if it were used to make windows, it is also recyclable and composts very well.

2. How is it made?

A roll of material, which can be polypropylene or cellophane, is placed on a special machine and then “pierced” by a spiked ring to the desired density. The huge rolls of film are then cut to size and sent to the paper bag manufacturer, where they can be glued into the paper with the unperforated part.

3. What is the Puk-Puk test?

When the film has been microperforated, the quality is tested. In the so-called Puk-Puk test, i.e. when you try to tear it by hand, you test and check how stable the film is, how well it can withstand being pushed by food while still not tearing.