The fragmentation behaviour of brittle airy cereal foods is studied both numerically and experimentally. The food item is subjected to severe compression until densification stage. Experimental evidence of typical cellular material behaviour is pointed out by elasticity, cell collapse and densification regimes. Using an accurate description of the cellular structure determined by X-ray tomography, a numerical approach based on discrete element method is proposed in order to better explain the resulting fragmentation. The approach allows to reproduce the deformation stages and predicted results show good agreement with experimental mechanical responses, in terms of maximum force. Moreover, large size fragments are found to form as a consequence of small rupture events.