88C-11 |
Thermal properties of radish and alfalfa seeds as a function of temperature and moisture content |
J. YANG and Y. Zhao. Nutritional Sciences Department, University of Connecticut, 3624 Horsebarn Rd. Extension U-17, Storrs, CT 06269 Radish and alfalfa sprouts, a highly nutritious and perceived healthy food, have been implicated in multi-site outbreaks of foodbrone illnesses. A food safety intervention method of utilizing radio frequency (RF) dielectric heating has been suggested to eliminate pathogens on seeds. Brief exposure of seeds to RF field could be successful in eliminating foodborne pathogens without affecting normal seeds germination. The performance of RF heating is highly dependent on the dielectric and thermal properties of the materials that are in turn, strong functions of both temperature and moisture content. Our objective was to determine thermal conductivity and specific heat of radish and alfalfa seeds at a temperature and moisture content range that is applicable to RF heating. Thermal conductivity and specific heat were determined using a linear heat source probe technique and a modified calorimeter method, respectively. Thermal properties were measured at 5 different temperatures from 30°C to 80°C and at moisture content (MC) of 4.6% and 5.5% for radish seed, and 5.0% and 7.3% for alfalfa seeds. Thermal conductivity and specific heat of seeds are functions of temperature and moisture content. Regression models were developed to describe each property. Thermal conductivity and specific heat of radish seeds are described as: k=0.0007015T + 0.6867MC – 0.001778T*MC + 0.0007302; Cp=0.003752T + 4.508MC + 0.03728T*MC – 0.09172, respectively. For alfalfa seeds, the thermal conductivity is: k=0.0004669T + 0.15222MC + 0.003926T*MC + 0.04803; and specific heat is: Cp=0.007883T + 6.0289MC – 0.054003T*MC – 0.0483. Both thermal conductivity and specific heat increased with increasing temperature and moisture content. Little information from literature was reported on the thermal properties of vegetable sprout seeds. Generated information from this study would allow the appropriate design of RF system for eliminating pathogens from seeds, thus enhance food safety associated with consumption of vegetable sprouts.
Session 88C, Food Engineering: Physical and Chemical Properties
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