Effect of shear rate on microstructure and rheological properties of sheared wheat doughs

Abstract Structure formation in dough systems is the result of an interplay between processing conditions and subsequent interactions in the protein phase. These interactions can be both of a covalent (disulfide bonds) and physical nature and occur at all length scales. The aim of this work was to investigate the effect of simple shear deformation at various shear rates on wheat dough rheological properties, microstructure and GMP fraction. Shear processing was compared with a z-blade mixing. The contribution of disulfide bonds on different length scales was investigated using NEMI as SH-blocker agent. Dough strength and strain hardening decreased with the increase in shear rate leading to dough weakening. Sheared dough at low shear rate exhibited the highest strength among doughs under large deformation conditions. Mixing or shearing in the presence of NEMI strongly reduced fracture properties and GMP content of mixed and sheared doughs. Only the dough that was sheared at low shear rate still exhibited some strength and strain hardening. Large deformation results were integrated with linear viscoelastic properties using low shear rate–long time creep tests. Elastic compliance curves for reference doughs were lower than the dough containing NEMI. Shearing at low and intermediate shear rates gave similar elastic compliance. Dough rheological behaviour was interpreted in the context of polymer gels containing reversible cross-links and physical interactions. Shearing led to the formation of a heterogeneous structure. Very large protein domains were observed for dough at low shear rate, which became smaller upon higher shear rates suggesting that those structures are quite weak. When NEMI was present, large protein structures were lost more easily. The break-up of gluten domains during mixing and shearing was proposed to be a result from a different mechanism.

[1]  R. Hamer,et al.  Depolymerisation and re-polymerisation of wheat glutenin during dough processing. I. Relationships between glutenin macropolymer content and quality parameters , 1996 .

[2]  D. Plazek.  What’s wrong with the moduli Charley Brown? or Get the H out and go to L , 1992 .

[3]  R. Boom,et al.  A New Method to Study Simple Shear Processing of Wheat Gluten‐Starch Mixtures , 2004 .

[4]  J. Steffe,et al.  Rheological Behavior of Undeveloped and Developed Wheat Dough , 1997 .

[5]  R. Boom,et al.  Dough processing in a Couette-type device with varying eccentricity: Effect on glutenin macro-polymer properties and dough micro-structure , 2007 .

[6]  R. Boom,et al.  Microstructure formation and rheological behaviour of dough under simple shear flow , 2006 .

[7]  J. Bibette,et al.  Monodisperse fragmentation in emulsions: Mechanisms and kinetics , 2003 .

[8]  R. Boom,et al.  Effect of simple shear on the physical properties of glutenin macro polymer (GMP) , 2005 .

[9]  R. Hamer,et al.  Understanding the link between GMP and dough: from glutenin particles in flour towards developed dough , 2003 .

[10]  J. Steffe,et al.  Mixing wheat flour and ice to form undeveloped dough , 1996 .

[11]  F. Békés,et al.  Glutenin-protein formation during the continuum from anthesis to processing , 1999 .

[12]  W. Lichtendonk,et al.  A model for the molecular structure of the glutenins from wheat flour , 1985 .

[13]  R. Hamer,et al.  The effect of mixing on glutenin particle properties: aggregation factors that affect gluten function in dough , 2005 .

[14]  M. V. Bruschke,et al.  Analysis of Dough Kneaders Using Numerical Flow Simulations , 2003 .

[15]  F. Macritchie.  Physicochemical Properties of Wheat Proteins in Relation to Functionality , 1992 .

[16]  T. Vliet,et al.  The Kieffer dough and gluten extensibility rig - An experimental evaluation , 2003 .

[17]  J. Skerritt,et al.  Examination of the structure of the glutenin macropolymer in wheat flour and doughs by stepwise reduction , 1998 .

[18]  R. Hamer,et al.  Depolymerisation and Re-polymerisation of Wheat Glutenin During Dough Processing. II. Changes in Composition , 1997 .

[19]  R. Hoseney,et al.  The formation and properties of wheat flour doughs. , 1990, Critical reviews in food science and nutrition.

[20]  O. Campanella,et al.  Rheological Properties of Dough During Mechanical Dough Development , 2000 .

[21]  E. Linden,et al.  Visualisation of biopolymer mixtures using confocal scanning laser microscopy (CSLM) and covalent labelling techniques , 2003 .

[22]  A. H. Bloksma.  Thiol and disulfide groups in dough rheology , 1975 .

[23]  Harjinder Singh,et al.  Application of Polymer Science to Properties of Gluten , 2001 .

[24]  P. Shewry,et al.  Understanding the structure and properties of gluten: an overview. , 2000 .

[25]  Marco P. Morgenstern,et al.  Rheology and the breadmaking process , 2003 .

[26]  M. Scanlon,et al.  Role of gluten and its components in determining durum semolina dough viscoelastic properties , 2003 .

[27]  Steve L. Taylor,et al.  Advances in Food and Nutrition Research , 2003 .