Fracture behaviour of bread crust: Effect of bread cooling conditions

The effect of air and vacuum cooling on the fracture behaviour and accompanying sound emission, moisture content and crispness of bread crust were investigated. Vacuum cooling resulted in rapid evaporative cooling of products that contained high moisture content. Fracture experiments showed a clear dependence of fracture properties on the way the bread was cooled. Vacuum cooling gave breads with a lower moisture content in the crust than the air cooled breads. Both fracture behaviour and sound emission by bread crust were affected by vacuum cooling. An increase in the number of force and sound events was found which correlated well with the increase in crispness. This treatment also resulted in better retention of crust crispness. Breads stored for 4 h at 22 C and 50% RH showed only force and sound events when vacuum was employed.