The moisture migration behavior of wheat starch/gluten blended powders and extrudates

Water migration plays an important role in the wheat-based products manufacture and is not only related to starch and gluten content, but also to the structure formed by gluten. Various gluten structure samples were constructed in powder and extrudate form. Density, moisture sorption isotherms, water migration rate, water binding energy of powders and extrudates were investigated. The average density of extrudates increased from 856 to 1321 kg m(-3), which existed a linear relationship with starch content. The shrinkage of the starch displayed higher than that of gluten when the water activity change from 0.35 to 0.11. The monolayer moisture content (M-0) of the starch was higher than that of gluten. Starch powder had a higher desorption rate and lower sorption rate than gluten, however, starch extrudate had higher sorption and desorption rates than gluten, for the extruded gluten has formed a network structure. The binding energy of the starch was higher than that of gluten, and which of all samples was close to zero when moisture content was greater than 20%. Those information on moisture migration behavior may guide to optimize the drying processing with balance of noodle quality, noodle yield, and energy consumption.

Automated summary

Water migration in the manufacture of wheat-based products is closely related to starch and gluten content, as well as the structure formed by gluten. The density of extrudates increases with starch content, while starch shows higher shrinkage than gluten. Starch has higher desorption rate and lower sorption rate compared to gluten.