Effect of cooking and drying on the thermal conductivity of rice

Abstract

The transient line source technique was used to determine the thermal conductivity of rice during cooking and drying of cooked rice. A temperature range of 50-70°C, moisture content of 10-70% (wet basis), bulk (packing) density range of 500-850 kg/m 3 and porosity range of 0.265-0.7 were studied. Thermal conductivity increased with increasing temperature, moisture content and bulk density, and the values were in the range 0.082-0.543 W/m °C. This value is comparable with the literature values for granular and gelatinized starch. The data on the effect of phase change due to gelatinization have also been included. The experimental values were statistically analyzed and empirical polynomial equations were developed in terms of temperature, bulk density, porosity and moisture content of rice during cooking and drying the cooked material.

Interrelationships between leaf heat conductivity and tissue structures of different varieties of Populus tomentosa Carr.

“…Table 3 shows the relations of heat conductivity, water content and leaf structures. The positive correlation between leaf conductivity and temperature agrees with results elsewhere (Remesh, 2000;Lan et al, 2002). The water content of 30-year-old leaves is slightly more than that of 3-year-old leaves.…”

“…This implies that the older the tree, the larger the heat resistance and the smaller the heat conductivity. It also indicates that the higher the temperature, the larger the heat conductivity (Remesh, 2000;Lan et al, 2002). Their correlation coefficients Fig.…”

Suitability of thin layer models for infrared–hot air-drying of onion slices

“…The lower values of RMSD, S D and E (%) are chosen as the criteria for goodness of fit (Ramesh, 2000) and same was followed in the present study.…”

“…A model is considered to be good when the correlation coefficient value (R 2 ) is higher and the mean square error (MSE) is lower (Noomhorm & Verma, 1986). Ramesh (2000) used the following statistical parameters to evaluate the comparative results.…”

Prediction of thermal conductivity of kernels and a packed bed of brown rice

“…Many studies on the effective thermal conductivity of grains such as corn, barley, minor millet, and wheat (Alagusundaram, Jayas, Muir, & White, 1991;Bhumbla, Singh, & Singh, 1993;Chang, 1986;Kayisoglu, Kocabiyil, & Akdemir, 2004;Kustermann, Scherer, & Kutzbach, 1981;Subramanian & Viswanathan, 2003;Tagawa, Muramatsu, Kasai, Iimoto, & Murata, 2005), have been reported. Ramesh (2000) examined the effect of cooking and drying on the thermal conductivity of rice using the transient line source technique. Recently, thermal conductivity data for various beans were reported and the relationship between thermal conductivity, and temperature and moisture was examined (Irtwange & Igbeka, 2002;Kayisoglu et al, 2004;Perez-Alegria, Ciro, & Abud, 2001; Thomeo, Costa, & Lopes Filho, 2004).…”