17H-11 |
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E. Demirkol, Department of Food Engineering, University of Mersin, Ciftlikkoy, Mersin, 33343, Turkey, F. ERDOGDU, Food Engineering Dept., Mersin Univ., Ciftlikkoy-Mersin, 33342, Turkey, and T. K. Palazoglu, Department of Food Engineering, Mersin University, Ciftlikkoy, Mersin, 33342, Turkey. Increasing trade of ready to eat materials such as cookies highlights an interest in quality changes (cracking, checking due to non-homogenous moisture distribution) during baking. The most important parameter resulting in adverse quality changes is non-homogenous moisture distribution due to diffusion which is a function of temperature. To control and optimize a baking a process to maximize the quality, the exact values of heat and mass transfer parameters should be known. The objective of this research was to determine heat and mass transfer parameters during baking under natural convection conditions using a realistic approach applying the required empirical equations, governing differential equations, boundary conditions and experimental data. Moisture losses for infinite slab shaped cookies, prepared according to AACC Method: 10-50D, were determined using weight changes of cookies during baking at 190 to 220 C, and Chilton-Colburn analogy with the required empirical equations, boundary conditions and experimental mass flux values was used to determine the mass transfer coefficient. Heat transfer coefficient (h) was determined using an empirical equation, and diffusion coefficient (D) values were determined using an infinite mass transfer coefficient (k) assumption at the surface and through a known mass transfer coefficient evaluated through Chilton-Colburn analogy with the known heat transfer coefficient value. The heat and mass transfer parameters were found to increase with increasing temperature. The D-values changed from 6.7E-9 to 12.9E-9 mē/s, h-values changed from 8.9 to 9.1 W/mē-s, and k-values changed from 3.2E-5 to 4.3E-5 m/s in a temperature range of 190 to 220 C. Experimental determination of heat and mass transfer parameters are extremely important in modeling the baking processes, and use of realistic approaches, compared to other simple methods, e.g. lumped system, as presented are crucial to determine and to use the real values in different modeling and optimization procedures.
Session 17H, Food Engineering: Thermal processes
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