The application of numerical methods on one hand and simulation of various food processing techniques on the other hand could be effective methods in the process optimization such as reducing energy consumption and processing time and increasing product quality. The objective of this study was to apply variable air temperatures during drying process of garlic slices while reducing the drying time and maintaining the highest possible quality of the dried product. Therefore, drying process was simulated based on the numerical methods, and the proper time to change the air temperature was predicted using the product temperature profile. A high air temperature was applied at the beginning of the drying process (70 °C) and then during the process the temperature was decreased (50 °C) in a way that that the product surface temperature was never increased more than the critical temperature of 50 °C. The result of simulation was validated based on experiments at various drying conditions such as air temperature of 50, 60 and 70 °C and slice thickness of 2.5 mm. Based on the results of the study, by applying the variable air temperatures during drying process on samples, the drying time was reduced by 24% and the color quality of the samples was preserved. The final product produced by this method had higher quality (total color changes is 3.278) compared to the products dried at the higher constant temperature of 70 °C (total color changes is 6.71).
Keywords: Drying; Food color; Garlic; Numerical simulation; Product quality; Variable air temperature.
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