Hygroscopic behavior of banana (Musa ssp. AAA) flour in different ripening stages

Abstract

The objective of this study was to evaluate the hygroscopic behavior of ‘Nanicão’ banana flour at three ripening stages (2–9°Brix) using moisture sorption isotherms at 25°C. The flour samples were obtained using a fixed-bed drying process at 60°C. The BET monolayer procedure was used for the desorption analysis. The Halsey, Henderson, Oswin, Smith, BET and GAB models were fitted to the sorption data. All flours exhibited type II isotherms that were almost superimposed, indicating that the ripening stage of the banana did not alter the hygroscopic behavior of the products. According to the adsorption isotherms, the flour has microbiological stability (aw<0.6) at moisture contents below 13g H2O/100g dry base (d.b.). The monolayer moisture content indicated that the drying process of the ‘Nanicão’ banana should not proceed to moisture content lower than 7.10g H2O/100g d.b. to avoid unnecessary power consumption. A type-H3 hysteresis between the adsorption and desorption isotherms of flour was observed. The Oswin, Smith and GAB models provided the best fit for the flour adsorption and desorption data.