The effects of freeze-thaw cycles on the rheological properties of yeasted and non-yeasted frozen bread doughs

The effects of repeated freeze-thaw cycles on yeasted and non-yeasted frozen bread doughs were investigated by a series of fundamental rheological tests, including small stress amplitude oscillatory test, shear creep-recovery, and uniaxial and planar extensional tests. Results showed that yeasted and non-yeasted doughs tested under both shear and extension using small and large deformations were rheologically different. Yeasted dough exhibited significantly higher storage modulus (G') as measured by the small stress amplitude oscillatory test and lower compliance measured in creep recovery tests. The effects of freeze-thaw cycles were clearly displayed in non-yeasted doughs, especially in large deformations rheological tests. Resistance to deformation of non-yeasted dough was altered by freeze-thaw cycles, indicated by creep recovery tests conducted under 500 Pa creep stress. The extension failure stress of non-yeasted dough was affected by freeze-thaw cycles, indicated by uniaxial and planar extensional tests. The negative impact of freeze-thaw cycles in yeasted doughs was more pronounced for dough examined with extensional tests. This was revealed by a decreased strain hardening behavior of doughs after freeze-thaw cycles when tested by uniaxial and planar extensional tests. Large deformation tests, particularly under extensional deformations can assist in the understanding of the freeze-thaw impact on dough matrices.