At the beginning a few interesting Links on the topic cat food.

http://www.hauspuma.de/Gesundheit/Ernaehrung/trockenfutter.htm GER
http://www.tatzenladen.de/infoseiten/Wahrheit_ueber_Trockenfutter.html GER
http://www.savannahcat.de/katzenernaehrung.html GER
http://www.kretakatzen.de/KK-Ernaehrung.htm GER
http://www.holisticat.com/Home.html ENG
http://www.shirleys-wellness-cafe.com/animals.htm ENG
http://www.catnutrition.org/index.php ENG

As you can see I informed myself quite well about the topic cat food (this link list is only part of the information I collected).

Results of my research:
I agree with the authors of the above websites that dry cat food is definitely not the healthiest possibility to nourish your cat. BUT: It is a possibility to allow your cat to eat small bites of food over the whole day (especially for people who are not at home during the day). The choice for a high-quality dry food free of cereal is a good compromise if one is not able to handle the food issue without dry food (whatever reason). I chose for myself the following two products:

Applaws http://www.mpmproducts.co.uk/applaws_dry_food.asp?in_section=applaws
Orijen http://www.orijen.de/html/katze.htm

Wet cat food which you can find in supermarkets is mostly of low quality.  Low quality means that it contains sugar, caramel (other kind of sugar), synthetic pigments, attractants, flavorings and a bunch of antidegradants. Cats who are used to these synthetic additives may even reject high quality cat food. A change from low to high quality food pays off, as these additives are bad for teeth (sugar) and my lead to food intolerances or allergies and other disease. I will directly start with high quality food and I chose the following brands/producers:

Almo Nature http://www.almonature.eu/
Applaws http://www.mpmproducts.co.uk/applaws_cat_product_information.asp?in_section=applaws
Grau http://www.grau-gmbh.de/
Vet-Concept http://vet-concept.com

Now we need to wait and see which food of our choices our cat acutually eats and likes. The best would be if he likes all of them. Every producer adds different amounts of additives like vitamins and minerals to the food and therefore it is good to mix different brands to avoid overdose or deficits.

Besides wet cat food and a little bit of dry cat food during the day, I am planning to continue my studies on the topic of BARF (Bones and Raw Foods). At the beginning I will limit the BARF part of our cat’s food to less than 20%. With this limit I do not need to worry about necessary additives.