If someone wants to eat something that is not considered food (e.g. paper), is a bracha required? Obviously if one is, it would be shehacol.
This article is quite detailed on explaining when you don't need to make a bracha. The article contains source references, as well.
A bracha is recited when we experience pleasure from eating the food that God has provided. This primarily includes pleasure due to “taste” – i.e. pleasure in the mouth or throat.
Similarly, if a food is in a state where it is not fit for human consumption, it does not require a bracha because it is not considered food. A few examples:
- raw potatoes
- raw rice, raw peppercorns
- fruits that are [bitter or sour and] completely unripe
- spoiled or burned foods
The general rule is: If most people would not eat such a food even if they were really hungry, then no bracha is required. For example, the Guinness Book of World Records claims that someone once ate an entire bicycle over a period of months. If he was Jewish, he would not have said a bracha when eating the bicycle.
(I met someone years ago, who claimed that he ate everything on his plate, LITERALLY. This included eating the flatware! We didn't believe him until x-rays confirmed that his stomach had spoons, knives and forks in there. Let's just say that after a few days, he "forked over" his food :-) :-)