Influence of process conditions on the separation behaviour of starch-gluten systems

Separation of wheat flour into its constituents starch and gluten was studied using a cone-cone shearing device, with emphasis on the effect of rotation rate, processing time, temperature and water content. This study confirms the two step mechanism previously proposed for the gluten migration: aggregation of gluten protein into gluten domains that subsequently migrate to the apex of the cone. The results show that optimal process conditions for gluten migration are different from the process conditions for gluten aggregation. While gluten agglomeration (step 1) benefits from high temperature, low rotation rate and high water content, gluten migration (step 2) is positively influenced by a high dough viscosity and higher rotation rat

Influence of process conditions on the separation behaviour of starch-gluten systems

Separation of wheat flour into its constituents starch and gluten was studied using a cone-cone shearing device, with emphasis on the effect of rotation rate, processing time, temperature and water content. This study confirms the two step mechanism previously proposed for the gluten migration: aggregation of gluten protein into gluten domains that subsequently migrate to the apex of the cone. The results show that optimal process conditions for gluten migration are different from the process conditions for gluten aggregation. While gluten agglomeration (step 1) benefits from high temperature, low rotation rate and high water content, gluten migration (step 2) is positively influenced by a high dough viscosity and higher rotation rat

Influence of sodium chloride on shear flow induced starch-gluten separation from Soissons wheat dough

Wheat dough can be separated into a starch-rich and a gluten-rich fraction by subjecting the dough to curvilinear shear flow. This paper presents the effect of salt (NaCl) addition on the shear-induced separation process. The separation (defined as the changes in protein concentration in the various layers, compared to the starting material) was promoted by NaCl addition up to a concentration of 4 w%. Dough without NaCl showed limited separation, but this effect could be partly compensated by a decreased processing time. Rheology measurements did not show clear differences in G' and tan d value, for dough with different NaCl concentration. But, shear stress and normal force did vary for various NaCl concentrations when applying a constant shear rate. Nevertheless, the large differences in separation behaviour are probably more related to the influence of salt on gluten aggregation and properties resulting thereof, than the differences in dough rheological propertie

Quality of shear fractionated wheat gluten – comparison to commercial vital wheat gluten

The functional properties of gluten obtained with a shear-induced separation process, recently proposed by Peighambardoust et al. (2008), are compared with a commercially available vital wheat gluten. Two tests were performed. First, a relatively strong wheat flour, Soissons, was enriched with gluten protein. The resulting dough was then evaluated on its kneading performance. Second, a weak flour, Kolibri, was enriched to evaluate the baking properties. The wheat flour enriched with gluten protein obtained via the shear-induced separation process (SCG) showed comparable to improved gluten functionality relative to commercial available vital wheat gluten protein (CVWG). The differences in functionality cannot be directly related to the composition as analyzed with SE-HPLC, because the composition of the gluten materials was rather comparable. The differences in functionality may therefore be related to the different drying techniques used or to the inherent mildness of the shear-induced separation techniqu

Influence of sodium chloride on shear flow induced starch-gluten separation from Soissons wheat dough

Wheat dough can be separated into a starch-rich and a gluten-rich fraction by subjecting the dough to curvilinear shear flow. This paper presents the effect of salt (NaCl) addition on the shear-induced separation process. The separation (defined as the changes in protein concentration in the various layers, compared to the starting material) was promoted by NaCl addition up to a concentration of 4 w%. Dough without NaCl showed limited separation, but this effect could be partly compensated by a decreased processing time. Rheology measurements did not show clear differences in G' and tan d value, for dough with different NaCl concentration. But, shear stress and normal force did vary for various NaCl concentrations when applying a constant shear rate. Nevertheless, the large differences in separation behaviour are probably more related to the influence of salt on gluten aggregation and properties resulting thereof, than the differences in dough rheological propertie

Quality of shear fractionated wheat gluten – comparison to commercial vital wheat gluten

The functional properties of gluten obtained with a shear-induced separation process, recently proposed by Peighambardoust et al. (2008), are compared with a commercially available vital wheat gluten. Two tests were performed. First, a relatively strong wheat flour, Soissons, was enriched with gluten protein. The resulting dough was then evaluated on its kneading performance. Second, a weak flour, Kolibri, was enriched to evaluate the baking properties. The wheat flour enriched with gluten protein obtained via the shear-induced separation process (SCG) showed comparable to improved gluten functionality relative to commercial available vital wheat gluten protein (CVWG). The differences in functionality cannot be directly related to the composition as analyzed with SE-HPLC, because the composition of the gluten materials was rather comparable. The differences in functionality may therefore be related to the different drying techniques used or to the inherent mildness of the shear-induced separation techniqu

Starch-gluten separation by shearing: Influence of device geometry

Wheat flour was separated into a gluten-enriched and a gluten-depleted (i.e. starch-rich) fraction within a conical shearing device. This paper describes the effect of the device geometry on the separation process. The gap distance between the two cones and the cone angle could be varied leading to a change in shear rate profile. The geometry influenced the aggregate formation and the following migration of the aggregates to the centre (of the cone). This study confirms that the primary aggregation is mostly influenced by shear rate, while migration of the aggregates is influenced by shear stress. However, constraining the dough by the walls of the cones also influenced the inward migration of gluten. Gluten clusters were found in all cases, but their migration to the centre only starts when they become similar in size compared to the space between upper and lower cone. It is concluded that the separation mechanism consists of three steps, rather than two. The results indicate the importance of confining the dough in between the two cones. Obviously, restriction of the growth of the gluten aggregates is a prerequisite for gluten migration. It is therefore clear that not only the shear rate but also the exact configuration of the shearing device is important for separation. This insight may lead to significant optimisation of the process of separation by shearing. The new insights were captured in a conceptual map with variables' shear rate, time and system geometry, which indicated in which regions only aggregation and in which regions only migration may be expected

Influence of process parameters on formation of fibrous materials from dense calcium caseinate dispersions

Concentrated calcium caseinate (Ca-caseinate) in the presence of palm fat forms hierarchical fibrous materials after enzymatic crosslinking under well-defined deformation. The presence of fat induces the protein fibers to be arranged in bundles of 200 fibers, separated by layers that are concentrated in fat. We investigated the effect of shear rate; shear time and protein concentration on the formation of fibrous materials in the two-phase protein¿fat system. The ratio between crosslinking rate and shear rate determined whether a fibrous structure was formed or not, indicating a subtle interplay between material properties and process conditions. Prolonged shear time influenced the transition from fibrous materials into damaged structures accompanied by syneresis. The experimental results are concluded in a generalized diagram, which provides an initial explanation of the structural transitions induced by solidification and shear