Moisture Adsorption Behavior Of Biscuitsformulated Using Wheat, Oatmeal And Passionrnfruit Flour

摘要

Moisture adsorption isotherms from a new biscuit considered as functional food were determined using a gravimetric static method at 25 and 40C and over a range of relative humidity from 0.112 to 0.903. The biscuit had 2.5, 3.3, 10.0 and 31.0% of ash, fiber, protein and fat, respectively, and 4.7% moisture content. The equilibrium moisture content of the biscuit (kg/ kg) increased when the storage temperature at any given water activity (Aw) was reduced. The experimental data were analyzed using different models, namely Guggenheim-Anderson-de Boer (GAB) (three-parameter relationships), Henderson and Oswin (both models with two parameters), which exhibited a sigmoid shape at the studied temperatures. The maximum isos-teric heat of sorption was 21.6 kJ/mol, which exponentially decreased when the moisture content was increased. The GAB model was found to be the most suitable for describing the adsorption characteristics at the temperature and A_w range studied, according to the relative error and the coefficient determination.