Otimização das condições da cinética de secagem de grãos de soja

Abstract

Brazil is the largest soybean producer in the world market. The protein of this legume is the property of greatest commercial interest to the industry as it is used as a raw material for the manufacture of human and animal food products. Thus, it is essential to develop scientific studies in the area of drying and storage of soybeans, aiming at maintaining their physiological quality. Applying heat to these seeds is an effective way to reduce their water content and activity, so it is essential to establish an optimal temperature and operating time to carry out the process without unwanted chemical reactions and protein denaturation occurring. The amount of water available in a sample has a significant influence on the growth of bacteria and fungi. Therefore, the present work aims to: (i) evaluate the drying of soybeans at three operating temperatures (65º, 85ºC and 105ºC) during 6.5h and 24h; (ii) build drying kinetic curves and relate them to models in the literature; (iii) estimate the operational cost of this process and calculate the savings generated after reducing the drying time; (iv) establish a standard methodology for carrying out soybean drying. It was found that the experimental data fit very well in all predicted models, with R² greater than 0.98 in all cases. The experimental procedure performed in 6.5 hours can reduce the economic and energy costs of the operation by up to 73% in the three tests, having no impact on the choice of the best operating condition. Therefore, taking into account the influence of high temperatures on the physiological quality of the grains, it was indicated, after the tests, the use of a temperature of 65ºC for 6 hours and 30 minutes to perform the drying.