29E-12 |
Cooling of carrots in acrylic boxes |
D. RAJU and T. R. Rumsey. Dept. of Biological & Agricultural Engineering, Univ. of California, Davis, 1 Shields Ave., 2030 Bainer Hall, Davis, CA 95616-5294 Carrots are packed in acrylic boxes and cooled in commercial cooling facilities. Reducing the cooling time in such units improves the quality and marketability of the carrots. Hydro cooling and forced air cooling are the possible cooling options. Experimental data on forced air cooling of carrots is scarce The objective of this research was to determine the cooling time and moisture loss for forced air cooling of carrots at various airflow rates. The carrots were procured from a local store and stored at 25°C, 24 hrs prior to the cooling trials. Five carrots were chosen randomly, their dimensions were measured and three T-type thermocouples were placed at different predetermined positions in those carrots. Carrots were placed inside an acrylic box along the lengthwise direction and cooled in a laboratory scale air cooling unit. Airflow was adjusted in the lengthwise direction at three different flow rates (0.009, 0.0012 and 0.0015 m³/kg of the product) at an air temperature of 0°C. Temperature variations among carrots located at various positions of the acrylic box and temperature variations within individual carrots were recorded till 7/8th cooling was achieved. Mass loss in the carrots was also measured. The mass loss at the three different flow rates was 0.8, 1.1 and 6 % respectively while the cooling times were 2.17, 0.98 and 0.95 hrs respectively for 7/8th cooling. This indicated that the mass loss in forced air cooling is significant at higher flow rates while cooling times are significantly longer at lower flow rates. The temperature profiles for individual carrots varied with the position of the carrot in the acrylic box and the size of the carrots. Thus there is a need to model the system and optimize airflow rate to achieve shorter cooling time with minimum mass loss in forced air cooling.
Session 29E, Food Engineering: Transport processes and kinetics
|