Moisture Desorption and Thermodynamic Characteristics of Nixtamalized Maize and Fermented Cassava Flour Blends

This study examined the moisture desorption and thermodynamic characteristics of four blends from nixtamalized/non--nixtamalized maize flour and fermented/non-fermented cassava flour.Maize grains were nixtamalized by their cooking in 1% Ca(OH) 2 solution and 18 h steeping.Cassava flour was fermented by the backslopping method.The flour blends were constituted in the ratio of 2:1 (w/w) of maize to cassava flour.Desorption isotherms were determined at temperatures ranging from 10C to 40C using a gravimetric method.The experimental data were fitted to the Guggenheim-Anderson-de Boer (GAB), Brunauer-Emmett-Teller (BET) and Oswin models to characterize the moisture desorption behavior.Results revealed that the use of nixtamalized and fermented flours in blends significantly influenced the desorption isotherms yielding type II isotherms.BET and GAB models exhibited percent root mean square of error at <10%, with the GAB equation showing the best fit for the desorption data.The monolayer moisture content (M 0 ) decreased with increasing temperature for all blends, and those with fermented cassava flours had lower M 0 .The net isosteric heat of desorption decreased as equilibrium moisture content increased, reflecting the progressive saturation of high-energy binding sites.The blends with nixtamalized flour exhibited reduced isosteric heat compared to the sample with untreated flours.The differential entropy of desorption increased as the equilibrium moisture content increased and, thus, indicated thermodynamic compensation.The study demonstrates that nixtamalization and fermentation influence the water-binding characteristics of maize and cassava flour blends, with implications for improved drying efficiency and extended shelf-life.