It is well known that fibre is very important in human diet. Distinct segments of the population, for different reasons, would welcome the existence of ready to use food with high level in fibre.

This work is a contribution to understand the role of fibres in a traditional food – cookies or biscuits. These are also convenient foods, easy to carry pocket food, without any special storage requirements. Fibre is known to be determinant of food structure, namely the insoluble fibre has a strong impact on food texture.

The aim of this work is to optimise cookies formulations, using fibre from different sources (oat, orange and pea). Fibre, fat and cooking time were the independent variables considered. Texture, colour, moisture and water activity were the responses, completed with phase transition temperatures information.

The effects of the various ingredients, interacting together, were studied and the optimum formulations for cookies were determined using a Central Composite Rotatable Experimental Design with five levels for the variables. The glass transition temperature (Tg) was measured by Differential scanning Calorimetry.

This study demonstrates the potential use of dietary fibre as a functional ingredient at levels up to 6 - 8%. The textural characteristics of cookies produced with those levels are more lipids than fibre dependent. This means that those levels of fibre can be used in the cookies base formulations, and still producing cookies within the commercial texture standards.