Granulometry of bread crumb grain: Contributions of 2D and 3D image analysis at different scale

Six bread crumbs were prepared from three different recipes and three baking procedures. Images of crumb were acquired in 2D at a macroscopic scale by using a flat bed scanner (resolution 85 μm) and in 3D at a local scale by X-ray tomography (resolution 10 μm). The cellular structure was assessed by mathematical morphology. 2D image analysis was completed by principal component analysis. The first principal component was found to reflect crumb fineness, in agreement with the mean cell size determined in 3D at a local scale. 3D mean cell wall size were about 220 μm and were not significantly different. The second principal component was linked to the 2D macroscopic heterogeneity of the crumb and to the macroscopic cell wall thickness. 2D images can be applied to the rapid control of crumb grain and could be used to quantify the cellular structure for the calculation of mechanical properties.