WATER SORPTION ISOTHERMS OF SHORT CHAIN FATTY ACID (SCFA) CAPSULES: EVALUATION OF MATHEMATICAL MODELS

Short chain fat acids (SCFA) were produced using whey permeate as raw material. The fermentative process was conduct by batch fermentation (30 degrees C/72h) on a bioreactor by Propionibacterium freudenreichi PS1 and the microencapsulation process was carried out on a laboratory spray dryer (inlet air temperature: 180-200 degrees C; feed flow rate: 24 g/min) using maltodextrin (10% dry matter) as wall material. Five mathematical models of the literature and widely applied in the prediction of moisture adsorption isotherms were analyzed. The experimental points of the moisture adsorption isotherms of the product at 25 degrees C and 40 degrees C were fitted by regression analysis. This study aimed to determine a model that better explains the water exchange between the atmosphere and the capsules of SCFA. Regression analysis was used to adjust the mathematical models to the experimental data of the adsorption isotherm. The software ASSISTAT 6.6 was used to fit the models. The Oswin equation (E-25 degrees C = 0.32% e E-40 degrees C = 0.13%) presented the best results among tested models.