THERMOPHYSI CS 2006 Proceedings of the seminar October 2006 68 THERMAL PROPERTI ES OF BI OLOGI CAL AGRI CULTURAL MATERI ALS Milena Jiřičková, Zbyšek Pavlík, Robert Černý Czech Technical University in Prague, Faculty of Civil Engineering, Department of Mechanics, Thákurova 7, 166 29 Prague, Czech Republic, email: jiricko@fsv.cvut.cz, pavlikz@fsv.cvut.cz, cernyr@fsv.cvut.cz Abstract: Thermal conductivity and specific heat capacity of several types of granular agricultural products, namely of spring oat, wheat mixture Axis, barley mixture Expres, corn mixture and soybean Evans is measured in dependence on moisture content from the dry state to the water fully saturated state. An impulse technique is used for the measurement. The obtained results will find use in the selection of suitable methods for processing of agricultural products, in a qualified assessment of optimal modes of technological processes, and in the development of modern fully automatic agricultural equipments. Keywords: Biological agricultural materials, thermal properties INTRODUCTION Biological agricultural materials consist of highly heterogeneous sets of different substances, mixtures and structural components, including complex organic structures. Their inhomogeneous composition and high variability affect their behavior and cause complicated and variable physical properties. Physical properties of biological agricultural materials are dependent on moisture and temperature of the studied material, and mostly show a considerable hysteresis. Complete knowledge of physical properties of agricultural materials has a decisive importance for the realization of many technological processes, especially for monitoring their quality and health harmlessness during their production and storage. The quality assessment and guarantee of the safety of foodstuff belong to the main priorities in food industry. HACCP – Hazard Analysis and Critical Control Point System [1] represents scientifically sophisticated approach to the problems of the protection of foodstuff quality. It is internationally accepted system guarantying the foodstuff safety aimed to the identification, evaluation and risks control in the whole technological procedure of foodstuff production. Its successful application is subject to the complete knowledge of physical properties of foodstuff. From the point of view of optimization of a technological procedure the temperature and moisture have the crucial importance. They present the most important parameters having clear relation to the character of physical, chemical and physiological processes in biological agricultural materials. Physical processes, above all heat and moisture transport, affect the intensity of physiological processes, nominally of breath, germination, microorganisms progress and many others and in consequence determine the final quality of food sources. The modern trends in storage and subsequent processing of agricultural products are currently based on application of complex mechanization and automation. For their optimization, it is necessary to know physical material parameters and to relate them with the environmental conditions.