How to make... porridge

The technological process is called extrusion. There is nothing complicated behind this mysterious and sometimes rumored term. On the contrary. It is a relatively simple procedure.

An extruder, i.e. the device in which extrusion takes place, is actually a kind of meat grinder. Only larger. Carefully selected raw materials (cereals) are evenly moistened and mixed before entering the device. The material prepared in this way enters the extruder. Similar to a meat grinder, in our case a pair of screws moves it towards the matrix (the outlet at the end) and kneads it, of course. Due to intensive mechanical stress, the pressure increases compared to a meat grinder and the temperature also gradually increases to 100–120 °C. Thanks to this, starch in the cereals is lubricated. It is similar to when we cook pudding. This changes their texture and creates a mass similar to porridge. It is gradually pushed to the exit holes of the matrix. Once it is outside in the open, only atmospheric pressure acts on it, and the mash "inflates" and a fragile, porous mass is created, which you may know as crisps. These are cooled at room temperature and further ground to the required granulation so that the mash has a pleasant texture when prepared again.

During the entire process, the cereals are exposed to a temperature of max. 120 °C, and this, unlike cooking, is only for a few seconds. However, similar to cooking, during this time, proteins are denatured and starches are lubricated, so that complex molecules change their structure and become more digestible. Thanks to this treatment, the porridge does not have to be cooked during preparation, but only allowed to swell.

Cereals in general are a natural source of B vitamins and vitamin E. Vitamin E is among the substances that are relatively stable to temperature. Of the B vitamins, vitamin B1 is the most sensitive. Of course, its losses also occur during extrusion (it is written about 30%). But for comparison - during cooking, losses of up to 75% occur (depending on the length of cooking) and about 35% during frying. The loss is smaller for other B vitamins. During extrusion, valuable minerals are also not leached into the water. A short heating (on the order of seconds) does not cause too much loss, but is sufficient to eliminate all undesirable microorganisms. By simultaneously reducing the water content, the product remains durable even without the use of preservatives.