Interaction of hydroxypropylmethylcellulose with gluten proteins: Small deformation properties during thermal treatment

The possible interaction between hydroxypropylmethylcellulose (HPMC) and gluten proteins has been investigated in order to understand the effect of the HPMC in bakery products. Dynamic oscillatory studies at small deformations indicated that the presence of varying concentrations of HPMC induces a softening effect (decrease in G' and G") in the gluten dough. During heating of HMPC-gluten mixtures, HPMC gelation only became evident when a minimum amount of HPMC was present (HPMC/gluten ratio was 0.075), conferring some strength to the gluten dough at 85 degrees C. The presence of HPMC did not modify the viscoelastic behaviour of gluten dough during cooling, however, at 25 degrees C, increased G' and G" were observed with HPMC. Gluten proteins increased their solubility in sodium dodecyl sulphate in the presence of HPMC, which besides the viscoelastic results, suggests that HPMC could interfere with the protein association and its further aggregation during heating, likely occupying the space of the proteins in the gluten network. Therefore, separate from interactions of starch and HPMC, the HPMC effect on bakery products could be partially due to the functional replacement of the gluten proteins in the gluten network. This effect is intensified after HPMC gelation, and also modifies the protein self-association during baking. (C) 2006 Elsevier Ltd. All rights reserved.