An instrumented pilot scale oven for the study of French bread baking

A static oven designed for French bread baking has been instrumented to monitor the processing conditions and record variables responsible for dough changes. Thermocouples are inserted at fixed position in the dough, mass loss is continuously weighed whereas expansion is measured by CCD video camera. Internal pressure and ambient humidity are controlled. Standard conditions for acceptable bread are checked and variable profiles measured in order to define the different sequences of variables related to the main macroscopic changes: expansion, scars opening and crust setting. This scheme is confirmed by modifying main operating conditions (temperatures and vapour injection), showing that water vapour favours expansion, reaching its maximum up to 1.7, at a crumb temperature close to 90 °C, in relation with internal pressure (90 kPa). Vault and hearth temperatures mainly influence crust, the setting of which stops loaf volume decrease (20%).