The densities of food products undergoing baking processes in commercial multi-zone band ovens of a local plant were measured with a volume replacement method along with a photographic procedure. Three kinds of cookies were selected as the sample products. It was found that the densities are closely related to the temperature and moisture conteni of cookies during the baking processes. This relationship is statistically represented by polynomial regression equations. The correlation coefficients were better than 0.970. According to the examination of changes in volume of cookies undergoing baking processes, expansion ratios were found to be 2.0-2.5.

A new procedure was developed to determine the specific heat of food products by using a calorimeter which was prepared through the proper modification of a household vacuum jar. Since there was no direct contact between food and heat exchange medium in the calorimeter, the evaluation of heat of solution for dissolvable chemical entities in the food was eliminated and also this new method is readily applicable to food whose temperature is higher than 100°C. The reproducibility and reliability of the developed procedure were carefully examined by using several materials whose specific heat values were well documented. This procedure was utilized to determine specific heat values of four cookies, wheat flour and one fresh produce. The agreement between the experimental and literature values was found to be excellent. The standard deviations of replicated experiments were less than 2%.

The moisture sorption isotherms of six different coffee products were determined at 20 and 30°C by a standard procedure which used saturated salt solutions. According to the analysis of variance applied to collected adsorption data, we observed that different drying methods (M), temperature of adsorption (T), and environmental relative humidity (RH) significantly influenced moisture adsorption by the product. It was also observed that interactions between M and decaffeination as well as between M and RH were also statistically significant. Monolayer values and sorption heat values were estimated from the isotherms by using the BET and ClausiusClapeyron's equations.