Study of White-Bread Structural Evolution by Means of Image Analysis and Associated Thermal History and Water-Loss Kinetics

The objective of this work was to use image analysis to study structural changes in bread crumb during baking and to derive correlations with moisture loss and the thermal history of samples. Samples of white - bread dough were baked at 220 ° C, removed after a preset baking time, and stored frozen for analysis. Digital images were taken from samples representing every 50 s of the baking process for up to 1200 s. Bread - crumb grain features obtained from the images were related to temperature kinetics and moisture loss. Two stages were observed during baking that were related to the size evolution of the cell. The fi rst stage, corresponding to a marked enlargement of loaves, was characterized by bubbles that were considerably larger than those visualized in the second stage, in which large bubbles coalesce and a homogeneous bread - crumb structure prevails. Water and ethanol escape during the second stage, thus reducing internal pressure. During the fi rst stage, nonlinear moisture loss kinetics were observed that may be partially due to the formation of bread crumb from dough. During the second stage, moisture loss had a more linear tendency, perhaps because of a more homogeneous dehydration of the samples.