Study of temporal and spatial porosity distribution of fermenting bread dough by CT-scan and image processing

Bread is a porous product with spongy texture. Given the importance of bread dough porosity distribution in terms of the impact on thermal conductivity that is important in the baking step and on the other hand its direct connection with leavening and dough volume changes, evaluation of porosity in bread dough is recognized as a necessity and has been chosen as the basis of this research. Among the methods used to evaluate porosity, the imagine method by using CT-scan and image processing was taken. To do so, three operational steps were carried out: 1. Preparation of bread dough with specific formulation and set condition. 2. Imaging of the fermenting dough by CT-scan in the four times (35, 70, 90 and 160 minutes). 3. Quantitative and qualitative calculation of porosity distribution during the fermentation time and position of cross-section-examined in the dough (Lateral, medial and central) and also evaluation of porosity distribution pattern in each section of dough. Mentioned parameters were obtained through the implementation of image processing techniques on CT-scan images and final results were able to interpret and compare. The results showed that the porosity alterations during the elapsed fermentation time have ascending slope and consequently rising proceeding. The distribution and continuity of porosity in the central sections were more than lateral and medial ones. Indeed porosity distribution near dough crust is minimal whereas close to the center rises and in the center of the dough reaches to its maximum. Pores distribution in each section was further concentrated in the bottom of the dough. Considering the images, growing and distribution of the porosity always start at dough base and grow upward. However, at the end, both mentioned porous parts joined and uniform porous structure was formed.