latent heat of vaporization for selected foods and crops

Cenkowski, S., Jayas, D.S., and Hao, D. 1992. Latent heat of vaporization for selected foods and crops. Can. Agric. Eng. 34:281-286. The equation for latent heat of vaporization was estab lished based on published equilibrium moisture content curves for main crops and selected foods. For moisture content (mc) above 0.2 db, there is little difference between the heat of vaporization from the grain kernels, hfg*, and that of free water, hfg. Below 0.2 db, this difference increases significantly for grains such as corn and rice. For the other grains (wheat, barley, bean, peanut kernel, soybean, sorghum), the ratio of hfg*/hfg increases at moisture contents below 0.12 db. There is a significant difference in hfg*/hfg results between durum wheat and soft or hard wheat. The latent heat of vaporization of free water is not significantly different from the latent heat of vaporization of water for celery, cloves, and eggs above 0.10 mc db and above 0.15 mc db for chamomile tea and horse radish. The hfg*/hfg ratios for starchy gels are 1.35 to 1.50, which were the highest of the tested crops and foods, for the moisture range between 0.11 and0.16db

Dynamics of drying bentonite in superheated steam and air as a model food system. Canadian Agricultural Engineering

Dynamics of drying bentonite in superheated steam and air as a model food system. Can. Agric. Eng. 38:305-310. The objective of this research was to compare temperature patterns, drying rates, and diffusivities of bentonite as a food model with a high concentration of solids dried in hot air and superheated steam at 160°C. In our preliminary investigations on the drying of liquid food droplets in hot air and superheated steam, spherical samples of 13.5 mm in diameter were prepared from chemically stable bentonite paste. In superheated steam drying, bentonite samples reached the saturation temperature for steam (100°C) after the first minute of drying. During this period the samples gained approximately 0.1 kglkg dry basis (db) of moisture, due to condensation of water on the surface of the sample. In air drying at 160°C, the temperature of a similar sized sample gradually increased to a wet bulb temperature of 80°C over a 10 min period. The drying rate in the superheated steam was higher by 8 to 10% than in the 160°C air in the initial stage of drying. However, this situation reversed when samples reached the falling rate-of-drying stage. For this period and below moisture content of 0.10 kglkg db, the overall diffusion coefficient was 50 to 80% higher for samples dried in the 160°C air than in superheated steam of the same temperature

The Canadian Society for Bioengineering La Société Canadienne de Génie Agroalimentaire et de Bioingénierie MEASUREMENT OF THERMAL CONDUCTIVITY OF PROCESSED FLOURS Written for presentation at the CSBE/SCGAB 2013 Annual Conference

ABSTRACT Thermal conductivity of five varieties of processed flours was measured using the non-steady state method. The result indicated that thermal conductivity of 0.06 ±0.00 W/(m 0 C) was obtained for the unconditioned groat ground flour (UCF) with largest moisture content, while the lowest thermal conductivity of 0.026 ±0.0016 W/(m 0 C) was obtained for the fined ground oat flour (FGOF) with lowest moisture content. And also, the results showed that bulk density has a significant effect on thermal conductivity for the low bran oat flour (LBOF). Increasing the bulk density from 484 to 607 kg/m 3 caused an increased in the thermal conductivity from 0.048 ±0.07 to 0.104 ±0.003 W/(m 0 C)