Enhanced aeration of part-baked bread using a novel combination of baking and partial vacuum

Abstract

An experimental approach to partial baking of dough rolls at low temperature (<105 °C) and partial vacuum (−20 kPa) was developed. The impact of various partial vacuum and heat transfers at the bottom of dough rolls during baking, on the oven-rise and the crumb structure of baked rolls was evaluated. Oven-rise and crumb structure obtained using partial vacuum were compared to those obtained using a commercial convection oven. A specially Magnetic Resonance Imager (MRI) designed oven was adapted with a temperature-controlled plate to modify the setting of the dough at the bottom of the roll. Dynamic and non-invasive assessment of the structure on the scale of the millimetre was carried out using Magnetic Resonance Imaging. The analysis of the mechanisms involved in the structure setting, on the local scale, was presented according to three stages identified in the oven-rise. No large gas cells and collapse were encountered at the initial lowering in pressure. Partial vacuum produced lower crumb density than that obtained at the atmospheric pressure. The setting of the periphery was involved in the partial collapse at the bottom at the later stage of baking and large rate-of-deformations were involved in the formation of large gas cells.