Analysis of radiant heating to produce an alternative frying process

Immersion flying is one of the most popular methods of preparing foods. Consumers enjoy fried foods due to convenience, low cost, and appealing taste. Sensorial properties include a golden color, crunchy crust, tender and moist core, and a pleasing flavor. Producers of fried products benefit from high throughput and sales of a value-added product.Unfortunately, there are several disadvantages of immersion frying and fried foods. Product disadvantages include variable oil quality and oil content in the finished material. The high caloric content of fried foods is primarily derived from the high oil content. With billions of pounds of fried foods produced and consumed each year in the United States, oil content in fried foods may be considered to significantly impact consumer health through obesity and obesity related health problems. Other problems associated with immersion frying include cost of waste oil disposal, need for use of caustic cleaning agents, and the large number of accidents associated with immersion fryers each year. An alternative immersion frying process would be beneficial to consumers and producers alike.The focus of this project was to study radiant heating as an alternative finish frying process. This overall goal was separated into three separate objectives: (1) an analysis of radiant emitters, (2) an analysis of quality indices of radiant heated potatoes, and (3) a numerical simulation of radiant heating of potato.Radiant emission from short, medium, and long wavelength thermal radiant emitter systems typically used for food processing applications were quantified. Measurements included heat flux intensity, emitter surface temperature, and spectral wavelength distribution. Heat flux measurements were found highly dependent on the incident angle and the distance from the emitter facing. The maximum flux measured was 5.4 W/cm2. Emitter surface temperature measurements showed that short wavelength radiant systems had the highest surface temperature and greatest thermal efficiency. The emitter spectral distributions showed that radiant emitter systems had large amounts of far infrared energy emission greater than 3 mum when compared to theoretical blackbody curves. The longer wavelength energy would likely cause increased surface heating for most high moisture content food materials.The effect of finish heating method: immersion frying, oven heating or dynamic radiant heating was evaluated for texture, color, and sensory properties of par-fried French fries. Peak breaking force was highest for radiant heated French fry samples. Color analysis revealed equivalent b-value (yellowness) of crust color for immersion fried and radiant heated French fries. Sensory evaluation indicated overall acceptability of radiant heated French fries equivalent to traditional immersion fried French fried potatoes.A numerical simulation of high intensity radiant heating was developed for a potato slab. The simulation predicted the temperature profile throughout in a one-dimensional slab. A surface crust and core region were defined and the increase in crust thickness was tracked during radiant heating. Measured surface and core temperatures showed excellent agreement with simulation results producing an average deviation of less than 3°C during 15,000 and 27,000 W/m2 constant flux heating. The simulation could be used as a tool to evaluate radiant heating of products to simulate immersion frying and crust formation.