4. Cooking-extrusion in the food industry. A case study

Influence of extrusion cooking on food constituents

Although it is difficult to give a precise description of the influence of extrusion cooking on food constituents: operating conditions, the product in which the constituent is found, extruders, etc. vary widely, we will try in the following lines to provide some answers, basing our comments on the phenomena observed in extruded cereal products.

• Protein: protein digestibility can be improved by extrusion cooking, as long as heat treatment remains moderate. If heat treatment is more severe, digestibility decreases. The Maillard reaction is also favored by heat treatment (the loss of lysine in cereal products can be very significant: 30 to 80%). Other amino acids seem to be partially destroyed by cooking-extrusion: arginine, histidine, aspartic...