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 ۱۱۰, ۱۵۰ and ۱۹۰ °C at a constant air velocity of ۰.۵±۰.۱ m/s and absolute humidity of ۰.۶ ± ۰.۰۴g 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 ۲.۸۸×۱۰-۸ to ۱.۱۱×۱۰-۷ m۲/s for bran free crisp bread and from ۲.۴۷×۱۰-۸ to ۸.۸۴×۱۰-۸ m۲/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 ۲۵.۲۲ and ۲۳.۴۳ kJ/mol, respectively..

کلیدواژه ها:

Bran ، Bread ، Drying ، Modeling ، diffusivity ، Activation energy