Effect of sprouting conditions on the properties of direct expanded extruded wheat

Abstract

AbstractThe present study investigates the use of flour from sprouted wheat for the production of extruded, directly expanded products. Until now, studies on the use of sprouted material in extrusion have not been concerned with differences in the sprouted material. This contribution documents the first attempt to study the effect of the variation of the sprouting process on extrudate properties. Extrudates were produced at standard conditions using material produced by the variation of sprouting times (steeped, 1, 3, 5, 7, and 9 days sprouted). It was found that an increasing duration of the sprouting process also increases the starch degradation and hence sugar generation. During this process, vitamin C levels showed an increase of up to 10‐fold. The accompanying changes in viscosity propagate systematically into different observations. With increased starch degradation back pressures in the extrusion die were reduced, extrudates show less sectional expansion, but densities were decreased because longitudinal expansion was increased significantly. The extrudates made with sprouted material were preferred during sensory assessment. The degree of sprouting, which was defined earlier proved to be a useful property to characterize the progress of the sprouting process and correlated well with changes observed for the sprouted flour and extrudate properties.Practical applicationThe use of sprouted wheat in the production of direct expanded extrudates is a promising opportunity to change and improve extrudate properties. On the one hand, the nutritional value of the extrudates is improved due to the use of sprouted wheat flour which contains newly synthesized vitamins, more essential amino acids, and a decreased phytic acid content. On the other hand, the texture of the extrudates is improved and less additives are needed in the production. Due to the starch degradation in the sprouting process short‐chain sugars were formed, which naturally increase the sweetness of the extrudates.