DESORPTION ISOTHERMS OF SUGAR BEET SEEDS

Abstract

Physical and chemical alterations of agricultural products may occur during storage, leading to quantitative and qualitative losses. Thus, knowledge regarding the relationship between the product and temperature (T) and relative humidity (RH) of the environment is required in order to diminish these possible alterations. Being that stated, this work aimed to determine the most adequate mathematical model to represent the equilibrium moisture content (Xeq) of sugar beet seed, cv. “Chata do Egito”, at different T and RH. Xeq was achieved by means of static method, using saturated saline solutions, attaining RH values between 11 and 96 %. Seeds were placed inside of dissectors containing the saline solutions, afterwards stored at BOD chambers under different T (10; 20; 30; 40 and 50 °C). Xeq was obtained when variation of three consecutive weightings was equal or lower than 0.01 g. Moisture content was determined by means of gravimetric method using a stove at 105 ± 1°C until constant mass. Five mathematical models (Chung Pfost, Copace, Modified Halsey, Henderson and Modified Henderson) were fitted to experimental data of Xeq. The best model was chosen considering the magnitude of mean relative error (MRE), standard error of the estimate (SE) and residual plots. The Chung-Pfost model was the one that best fitted to experimental data, presenting values of 8.04 % and 0.62 % d.b. for MRE and SE, respectively.