Application of gab or other models for water sorption isotherms determination of traditional bakery products

The vapour sorption isotherms of five typical baked foods were determined at
20°C. In particular, the methodology proposed by Cost Projects 90 and 90 bis have
been used. The latter procedure implies using a proper number of pieces of each
product. The products have been closed in desiccators, in which nine different
equilibrium relative (ERH) humidity have been created. The relative humidity inside
desiccators have been checked daily until equilibrium, before piacing sampies.
Moisture content of samples has been measured by a gravimetrie method, while
water activity has been determined by a dew-point hygrometer. AlI obtained data
have been interpoiated to fit the GAB equation or other equations and the mean
relative percentage deviation modulus (E%) calculated.