Effect of temperature, time and wheat gluten moisture content on wheat gluten network formation during thermomolding

A plastic-like material can be obtained by thermomolding wheat gluten protein which consists of glutenin and gliadin. We studied the effect of molding temperature (130-170 degrees C), molding time (5-25 min) and initial wheat gluten moisture content (5.6-18.0%) on the gluten network. Almost no glutenins were extractable after thermomolding irrespective of the molding conditions. At the lowest molding temperature, the extractable gliadin content decreased with increasing molding times and moisture contents. This effect was more pronounced for the alpha- and gamma-gliadins than for the omega-gliadins. Protein extractabilities under reducing conditions revealed that, at this molding temperature, the cross-linking was predominantly based on disulfide bonds. At higher molding temperatures, also non-disulfide bonds contributed to the gluten network. Decreasing cystine contents and increasing free sulfhydryl and dehydroalanine (DHA) contents with increasing molding temperatures and times revealed the occurrence of beta-elimination reactions during thermomolding. Under the experimental conditions, the DHA derived cross-link lanthionine (LAN) was detected in all gluten samples thermomolded at 150 and 170 degrees C. IAN was also formed at 130 degrees C for gluten samples containing 18.0% moisture. Degradation was observed at 150 degrees C for samples thermomolded from gluten with 18.0% moisture content or thermomolded at 170 degrees C for all moisture contents. (C) 2011 Elsevier Ltd. All rights reserved.