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B. E. FARKAS, B. J. Lloyd, and K. M. Keener. Dept. of Food Science, North Carolina State Univ., 129 Schaub Hall, Box 7624, Raleigh, NC 27695-7624 Immersion frying is widely used in the fast food industry, imparting desirable sensorial properties to foods while having a high throughput. Limitations to the process include an inherent variation in oil quality and need for oil handling and disposal. While fried products are highly desirable, their high oil content may have a negative impact on consumer health. An alternative frying process using radiant heating was developed. Critical to the success of the new process was the controlled application of radiant energy from the emitter to the product. Mathematical modeling was proposed as a potential tool in refining the process. The objective of this study was to develop and solve a two-dimensional simulation of convection and radiation heat transfer with variable emitter heat flux and target material properties. Temperature distributions were calculated for a square two-dimensional parallelepiped simulating a shoestring cut French fry. A uniform radiant energy was assumed incident upon the food surface, allowing shape factor considerations between the radiant emitter and the food material surface to be neglected. Penetration of radiant energy within the food material surface was assumed to follow Beer’s Law. Heat transfer equations included an internal generation term for absorbed radiant energy as well as conduction and convection heat transfer terms. Simulations were carried out for both steady and unsteady state heat flux conditions. The mathematical model was solved using explicit finite differences. A laboratory scale infrared heater was designed and constructed to produce finish fried materials. Simulated and experimental temperature profiles agreed well. Input conditions with greatest impact on output were radiant energy surface reflection and internal dissipation coefficients. The simulation now serves as a tool for determination of the heating effects of radiant processing parameters and material temperature profiles. Manipulation of model input variables may be done to optimize product heating.
Session 111, Food Engineering: Modeling heat transfer and microbial inactivation
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