Use of partial vacuum to decrease the baking temperature of double-layered flatbread

The delamination of layers (or 'puffing' effect) in flatbreads is mainly governed by heat transfer encouraging manufacturers and small-scale bakers to bake at high temperatures (up to 350 °C) and apply direct heat. The use of high baking temperatures to achieve delamination of layers during baking has raised concerns regarding excessive energy consumption, as well as considerations of food quality and safety. This study investigated use of a partial vacuum to enhance the double layering of flatbreads at low temperatures (160 and 200 °C) and for different dough thicknesses (2 and 4 mm). Temperature probes and camera were used to monitor the dynamics of deformation and energy transfer under a partial vacuum. To complement this evaluation, final quality attributes (water content, texture test, color and alkaline water retention capacity) were then analyzed for the most promising baking profiles. It is clearly demonstrated by this study that double-layered flatbread can be successfully par-baked or baked at 200 °C through the application of low pressure (∼50 kPa) to 2 mm thick dough. The role of the partial vacuum in bringing about an earlier boiling point is highlighted, which could boost the evaporative flow, complementing the direct effects of low pressure on gas expansion and desolubilization, and facilitate the delamination of layers.