A process for preparing a cereal bar comprising the steps of i) blending a food pieces mix comprising whole grain cereal pieces, with a whole grain cereal binder, and ii) forming a cereal bar from said mixture, wherein said binder is obtainable by a process comprising the steps of : a) contacting a whole grain cereal flour in water with an enzyme composition comprising at least a protease and an alpha-amylase, both showing no hydrolytic activity towards dietary fibres, to provide a whole grain flour hydrolysate, b) inactivating said enzymes when said hydrolysate has reached a stable viscosity comprised between 100 and 30,000 mPa.s measured at 65°C and a total solid content of 25 to 50% by weight, c) concentrating and mixing with a humectant and a fat component, to provide a whole grain binder.