The trick is that each cereal grain has its own gelatinization temperature. The temperature for malted barley (and other malted grains) is conveniently within mash range; but for most grains it is considerably higher. They need to be cooked in a cereal mash which ramps up to boiling -- or, far more conveniently, be pre-gelatinized in a process like flaking (where the soaked grits are passed between steam-heated rollers that cook and dry them all at once.) If your grain of choice is available as brewer's flakes (as are corn, wheat, barley, rye, oats and maybe others,) save yourself a lot of trouble and go that route. They go right in the mash.