The ingredients used in extrusion cooking are similar in general terms to those used in other food processes in that they must be of good food quality and, in the case of additives on the permitted lists, be of the required purity. However, there are special features of the extrusion processes which are unique in terms of the processing conditions, such as compression and shear at high temperatures, and may utilise characteristics of raw materials not normally thought to influence food processes. Extrusion is a relatively low moisture process operating in the range 10 to 40% moisture on a wet weight basis (wwb). It employs large mechanical energy and heat inputs in highly compressed powders systems which cause the powders to be transformed into fluids. [1,2] Therefore characteristics such as surface friction, hardness and cohesiveness of particles become important and in the high solids concentration of melt fluids developed within the screw systems the presence of plasticisers and lubricants causes significant changes to the system variables of the processes.