Properties of Starch after Extrusion: A Review

Food extrusion has evolved over the past decades and is now a unique research area. Starch is a primary ingredient of raw materials that are widely used in food extrusion. Extrusion is a thermomechanical process that can break the bonds of starch, leading to starch gelatinization, melting, and degradation. This article reviews the effects of extrusion on structure (crystallinity, morphology, molecular weight) and physico‐chemical properties (expansion ratio, water absorption index, water soluble index, texture, pasting property, and digestion) of starch. In addition, some applications of extruded starches are described. This review is of significance as it provides an overview of the effects of extrusion on starch properties and indicates the potential of extrusion applications in the food industry. Starches are the primary raw materials widely used in extrusion processing. Extrusion is a thermo‐mechanical process that significantly changes the morphology and fine structure of the starches, thereby giving new physicochemical properties to the starches. The properties of starches after extrusion may be varied with the processing parameters. In this review, the applications of extruded starches are also introduced.