A process of precooking grains which comprises the steps of: a) Charging the grains into a reactor in a controlled manner； b) Applying a first negative pressure to the reactor； c) Heating the grains contained in the reactor； d) Applying a second negative pressure to the reactor； and e) Cooling the grains. Equipment for precooking grains comprises at least one reactor, which is associable with means for applying negative pressure.
