Quantitative assessment of gas cell development during the proofing of dough by magnetic resonance imaging and image analysis

The structure of bread crumb is an important factor in consumer acceptance of bakery products. The noninvasive monitoring of the gas cell formation during the proofing of dough can aid in understanding the mechanisms governing the crumb appearance in the baked product. The development of gas cells during the proofing of dough was monitored in a noninvasive manner using magnetic resonance imaging (MRI) at 4.7-T. The acquired MRI time series were analyzed quantitatively using image analysis (IA) techniques. The effects of both kneading temperature and mechanical damage by molding were studied. When additional rheological stress was introduced during molding, a more heterogeneous (coarse) gas cell size distribution was observed, and the dough had a smaller specific volume (as measured by MRI). These characteristics were preserved in the bread crumb structure after baking. The fast-deformation during molding also resulted in an isotropic growth of the dough during proofing, whereas slow-deformation during molding resulted in anisotropic growth. This can be related to a better conservation of stress in the dough under a moderate molding operation. A higher temperature during kneading also resulted in a coarser distribution of the gas cells and a smaller MRI specific dough volume. No effect of kneading temperature on the growth anisotropy could be detected, however. This indicates that temperature has a smaller effect on the conservation of stress in the dough than molding. The current work illustrates the capability of MRI/IA for understanding and predicting the influence of food processing parameters on consumer-relevant features in a food product (bread).