Applicability of the BET and GAB models to the moisture adsorption isotherm data of some Ghanaian food flours

  • P_NT Johnson Food Research Institute, CSIR, P. O. Box M. 20, Accra, Ghana


The static gravimetric method was used to determine the moisture adsorption isotherm data, at 30 oC, of the food flours of cassava-starch, cocoyam, plantain, fermented maize meal, and blends of cocoyam, plantain, and cassava-starch for the aw range 0.1 to 0.9. The adsorption data obtained were fitted to the Brunauer-Emmett-Tetter (BET) and Guggenheim-Anderson-de Boer (GAB) models, by regression analysis, to estimate and compare the monolayer moisture contents of the food flours. The moisture adsorption isotherms were a mixture of Types I and II, according to the BET classification. The monolayer moisture content values, as predicted from the BET and GAB models, were comparable ranging from 4.13 to 7.61 per cent dry solids. The quality of the fitted models, as estimated by the relative percentage deviation modulus, clearly showed that both models can be used adequately to predict the monolayer moisture contents of the food flours.

Ghana Jnl agric. Sci. Vol.31(1) 1998: 107-112

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