30D-7 |
Thermal and dielectric properties of sweetpotato puree |
O. O. FASINA1, H. Stewart2, B. E. Farkas2, and H. P. Fleming3. (1) Department of Biosystems Engineering, Auburn University, 211 Tom E. Corley Building, Auburn, AL 36849, (2) Department of Food Science, NC State University, Box 7624, NCSU, Raleigh, NC 27695, (3) USDA-ARS, Box 7624, NCSU, Raleigh, NC 27695 Pureeing of sweetpotato is carried out to enhance the conversion of the roots into value-added products. During processing, production and home utilization, the puree is cooked and heated in a conventional oven or microwaved. The objective of the study was to quantify the thermal (specific heat, thermal conductivity and thermal diffusivity) and dielectric properties of sweetpotato puree within a temperature range of 5 to 80C. Specific heat of sweetpotato puree was determined by differential scanning calorimetry. The line heat source probe method was used to determine thermal conductivity. Thermal diffusivity was estimated from the measured values of thermal conductivity and specific heat. A network analyzer was used to measure the dielectric properties of the puree. Specific heat and thermal conductivity increased with temperature (5 to 80C) while thermal diffusivity decreased with temperature. The range of values for specific heat, thermal conducitivity and thermal diffusivity were, respectively, 3.70 to 3.78 kJ/kg K, 0.52 to 0.78 W/m K, and 1.98 x 10-7 to 4.25 x 10-7 m2/s respectively. Both temperature and frequency (900 to 2500 MHz) significantly affected the dielectric constant (60.54 to 73.02) and dielectric loss (16.50 to 29.53) of sweetpotato puree. The results from this study will be used in the design of operations, equipment and processes for sweetpotato puree and products derived from the puree.
Session 30D, Food Engineering: Physical and chemical properties
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