Understanding molecular weight reduction of starch during heating-shearing processes

Recent understanding of the mechanisms underlying the changes in molecular weight of starch as a function of process parameters during thermomechanical treatment, for example extrusion, holds promise towards more effective optimization of thermomechanical processes according to the desired modification of molecular weight. This paper summarizes recent advances in theoretical understanding and experimental methods. Empirical observations from extruder experiments can be better understood on this basis. The current status in this field has opened up potential for developing new equipment in which the main process parameters, which normally occur simultaneously, can be separated and optimized. This will create a much wider window for product-oriented process design and for new products.