An experimental study of the peeling of dough from solid surfaces

Binding, David; Couch, M.A., (2003) 'An experimental study of the peeling of dough from solid surfaces', Journal of Food Engineering 58(2) pp.299-309 RAE2008

This paper outlines experimental work concerned with the peeling of dough from solid surfaces. The findings of the programme are used to validate corresponding numerical simulations carried out at UW Swansea, with the eventual aim of improving the understanding of dough mixing. Simple idealized dough mixtures, including bread, biscuit and bagel type doughs, are first characterized rheologically in terms of shear viscosity, dynamic moduli and extensional viscosity, to provide a context for the peeling work. A capillary rheometer is then modified with the addition of a load cell and flat plates (made of Perspex, PTFE or steel with both square and circular cross-section having parallel or wedged orientation) to develop an apparatus capable of recording the force histories associated with dough peeling. The addition of a video capture technique makes it possible to determine the stresses associated with the peeling of the model doughs from these surfaces, by visualising the surface area in contact with the plates. These peeling stresses are found to be strong functions of strain, strain rate and compressive load and also depend on the plate surface, dough water content and dough mixing time. Radically different peeling behaviour is observed with biscuit type doughs and bread/bagel type doughs. The biscuit dough peels in a conventional manner, but the bread and bagel type doughs are observed to slide along the smooth plate before adhesion fails and true peeling begins. For a given dough and plate surface this failure of adhesion always takes place at a critical strain of 1.6 for the bagel dough and 1.3 for the bread dough. The data resulting from the study is then used to provide the numerical simulations with the appropriate conditions at the solid/liquid interfaces.

Peer reviewed