Shear-induced starch–gluten separation at very low water content aided by xylanases

Abstract

This study examines the influence of extremely low water content on shear-induced starch–gluten separation and how endoxylanases influence the separation by releasing water associated with arabinoxylan. Shearing was performed at a water content ranging from 34% to 43.5% (w/w). It was possible to concentrate gluten to 60% protein content in local gluten clusters and most of the concentration occurred within 5min. Contrary to higher water concentrations, a water content <40% resulted in local separation of starch and gluten but no inward migration of the gluten. Addition of an endoxylanase with a higher selectivity for water-unextractable arabinoxylans and an endoxylanase with a higher selectivity for water-extractable arabinoxylans both resulted in a significant reduction in torque. The major influence of xylanase was the release of 3–5% water (on a water basis), allowing separation at even lower water content. Furthermore, no significant differences were found between the enzymes.