Puffed rye and rice have a very porous matrix, made up of numerous cavities of different sizes separated by a very thin ‘wall’ puffed wheat, emmer wheat and barley on the other hand show a much more compact, homogeneous and less porous structure; puffed buckwheat is characterised by a large number of small and regular cavities. Moreover, puffing induces significant changes in the structure and physical properties of the starch and an increased water holding capacity of both the grains and the flours.