Isotermas de dessorção de diferentes cultivares de soja

Abstract

Soybean is a crop of global importance, widely used for the production of animal feed, production of oil and by-products, consumption in natura, having about 40% of proteins and 19% of lipids, being one of the largest producers of vegetable oil. For the maintenance of quality and safe storage, the drying step is one of the essential processes for the conservation of the desirable qualities of products of vegetable origin, with the moisture content being the most important factor for the quality control of the soybean processing industries. The objective of this work was to determine the desorption isotherms of different soybean cultivars using the static-indirect experimental method and to adjust different mathematical models to the experimental data of hygroscopicity of soybean grains of the cultivars (BÔNUS; M-7739; CD-2728; NS- 7300; BRS-7960; CD-2737). Data were collected from six soybean varieties that were harvested with a moisture content of approximately 18.0 % (wet base), used to correlate the water content of soybeans with the water activity of the product, a non-linear regression analysis was carried out in order to fit one or more models that best described the desorption phenomenon of the product. To verify the degree of fit of the model, the significance of the regression coefficient was considered by the t test, adopting the 0.05 level of significance, the magnitude of the coefficient of determination (R2), the values of the estimated mean error (SE), the relative mean error (P), the Chi-square test (χ2) with a confidence interval of 0.99 (p<0.01) and for the model selection, the Akaike Information selection criteria (AIC), and Schwarz Bayesian Information (BIC). The Modified Oswinmodel was selected to represent the desorption curve of soybeans from different cultivars. Based on the isotherms presented, the product can be managed properly, aiming to maintain its moisture content at the recommended levels for safe storage.