Revisiting water transport during bread baking.

DIASCORN, YVES; LUCAS, TIPHAINE; FLICK, DENIS; MARÍA M. URETA; V. O. SALVADORI

Conferencia; AACC Annual Meeting; 2018

AACC

The impact of the baking temperature on the water content (WC) profile during bread baking was analysed using a convection oven (three oven temperatures and different baking times). During baking local WC and temperature was measured at different regions of the crust and crumb. Results showed that water accumulated at core during the first part of baking; this was consistent with the theory of the heat pipe mechanism. WC reached a maximum level (at about 2.5%), with no effect of the baking temperature, and decreased slowly at advanced baking times. To our knowledge, this is the first time that the dynamics of water increase in dough core during baking was reported with reduced experimental bias. Regarding the crust, a model relating water loss roughly to the thermal resistance in the dry zone and the difference between the baking temperature and the temperature at the evaporation front was validated. The extent of starch gelatinisation for the different sample locations was discussed by plotting WC-temperature curves in a state diagram; this analysis concluded to intact granules or low degree of gelatinisation in the top crust and top, dry crumb. Initial WC in dough and heating rate encountered in the literature were compared to explain the contradictory reports about the state of starch granules observed in the top crust of bread. Water losses were also reported. The water lost by bread contributes significantly to the process energy consumption and its reduction is of concern for conducting the process in a more sustainable manner. A better optimization of heat transfer between the surface (for coloration purposes) and the core (for inflation purposes) could help in this way, together with shorter baking duration and hence higher yield.