2.3.5. Solubility (b) and diffusion (Dw)
coefficients of water in the films
The solubility
coefficients of water in the films (b) were determined
according to Larotonda et al. (2005), by the first derivative of
the film’s moisture sorption isotherm (GAB model) in relation to
the water activity (aw), divided by the water vapor pressure, ps, at
the sorption isotherm temperature. Physically, the coefficient b is
the partition coefficient of water between air and film, and is given
by Eq. (4).