Microstructural characterization of a wheat-based food material using image analysis and pore network modeling during baking

Abstract: Microstructural properties of wheat-based food materials change during baking. These alterations affect the final product's mechanical properties, physical attributes, and consumer satisfaction. Image processing and pore network modeling were used to analyze the variations in a cookie's microstructural properties during baking. Cookies were baked in an oven set at 184 ± 2°C for 10–60 min and then freeze-dried. Over 1500 two-dimensional images were collected for each sample using X-ray micro-computed tomography. Image processing and pore network modeling were utilized to obtain porosity, pore size distribution, tortuosity, pore coordination number, permeability, and other properties. A gas pycnometer was used to validate the obtained porosity values and calculate the solid density. Three stages of expansion, shrinkage, and subsequent expansion were observed during baking. The total porosity ranged between 0.145 and 0.373. The largest pores were observed in the 20-min baked sample, which had a moisture content of 8.53 g/100 g solids. Cookies baked longer had more interconnected pores than the 10-min sample, enabling them to conduct fluid at a higher rate. The absolute permeability values were between 1.75 × 10⁻¹¹ m² and 4.68 × 10⁻¹¹ m². The results suggested that porosity and pore coordination number had a similar trend as cookie permeability. Both heat and mass transfer during baking are expected to influence the development of the porous structure. Practical Application: Understanding the microstructural properties of wheat-based food materials is expected to help the baking industry control processing conditions, final product quality, and visual texture by adjusting the baking parameters.