Reheating characteristics of crust formed on buns, and crust formation

Abstract The idea of this paper to examine some characteristics of crust formation during baking of yeast leavened dough. The aim is to find the impact of the crust on the heat and mass transfer rates. In a second test series, buns were baked under different conditions, and the rate of crust browning and thickness evolution was followed. The aim was further to see whether a baking at 145 °C under high convective boundary conditions could match traditional baking (hot air at 175 °C and top–bottom at 200 °C). Ready baked buns were reheated some with and some without (peeled off) crust. The results show a difference in heating behaviour. The temperature in buns heated with crust rose faster and levelled off at significantly higher temperatures than in buns without crust. The buns heated without crust lost weight at a rate about three times that of buns with crust. Air temperature and velocity influenced the loss rate for both kinds of buns. For the comparative study, it was found that although the internal heating rate of the buns was similar for the three heating technologies, the crust browning was faster and greater in the traditional processes. It was also found that the rate of browning is not significantly increased by impingement, even when varying the air velocity.