Estudo da cinética da secagem de leveduras Saccharomyces cerevisiae para uso como fonte protéica na ração animal.

Abstract

The use of yeast, as an unconventional protein source, especially of the genus Saccharomyces cerevisiae, has been growing in recent years. When the yeast is intended for feed ruminant animals must be inactive and retaining their nutritional characteristics, such as protein and also the requirements of the as regards color, grain size and moisture content. The production of dry yeast emerges as one of the solutions to ameliorate the problems agriculture in the Northeast region. The drying process is a viable form for the preservation of the product, facilitating the storage, transportation and commercialization. In this work, a series of to the drying process of yeasts. Experimental curves were obtained using stove with forced air circulation in the temperature ranges of 34, 40, 55, 70 and 75 ° C and air velocity 0.1; 0.2; 0.4 and 0.6m / sec-1. The curves with the experimental results were obtained during the preheating periods the constant rate and decreasing rate of drying. Critical humidity between the two periods does not depend on the temperature range. For the decreasing rate period a Fjian diffusional model was applied. The survey of desorption isotherms, which is of fundamental importance in quantifying the hygroscopicity of the product at temperatures of 30, 40 and 45 ° C. These curves were adjusted through the mathematical models of HENDERSON, GAB and BET. The GAB model was the best fit for the experimental data in the temperature ranges studied. The nutritional value does not compromised with the increase of temperature since higher temperature decreases the drying time.