Hygroscopic behavior of lyophilized products can be visualized starting from the construction of Moisture Sorption Isotherms (MSI). Such curves show the relationship between the maximum amount of absorbed water for a substance, with the equilibrium vapor pressure or water activity, at a given constant temperature. Aimed to study later the reconstitution and use of biological materials of lyophilized bovine pericardium, it was plot adsorption and desorption curves, at temperatures of 15, 25 and 35°C, on HydrosorbTM 1000 - water vapor sorption analyzer. The results showed MSI type II, according BET classification, typical reaction of hydrophilic surfaces with monolayer and multilayer formation. Histerese phenomenon was observed during the whole MSI interval. The mathematical models of BET and GAB fitted well the experimental data and allowed the water monolayer calculation, estimate the critical level of residual moisture that assures more stability to the product.
Lyophilization; freeze-drying; bovine pericardium; hygroscopic behavior; moisture sorption isotherms
