Baking-drying kinetics of crisp bread: the influence of bran content and baking temperature

In this study, mathematical modeling of hot air baking-drying of thin-layer crisp bread was investigated. thin-layer drying process were conducted under three different temperatures of 110, 150 and 190 °c at a constant air velocity of 0.5±0.1 m/s and absolute humidity of 0.6 ± 0.04g water/kg dry air. it was found that the baking-drying process occurred in falling rate period over the baking-drying times. eight well-known thin-layer baking-drying models were fitted to the baking-drying experimental data of crisp bread, implementing non-linear regression analysis techniques. based on the coefficient of determination (r²) and root mean square error (rmse) values, it was concluded that the best models in terms of fitting performance for hot air baking-drying of bran free crisp bread were wang & singh and logarithmic while for whole-wheat crisp bread were page, logarithmic and wang & singh. the moisture transfer from crisp bread was described using the fick’s diffusion model. the effective diffusivity was within the range of 2.88×10-8 to 1.11×10-7 m2/s for bran free crisp bread and from 2.47×10-8 to 8.84×10-8 m2/s for whole-wheat crisp bread over the temperature range. the activation energy for bran free and whole-wheat crisp bread was found to be 25.22 and 23.43 kj/mol, respectively..