A rapid method to obtaining moisture sorption isotherms of a starchy product

The static gravimetric method proposed by the COST 90 project has been traditionally used to obtain moisture sorption isotherms for food, but it is limited to high relative humidity levels because of the extremely long equilibrium time allow fungal growth on the sample. The aim of this study was to test the applicability of an alternative method to obtain the sorption isotherms of cassava starch. Adsorption and desorption dates were measured at 25 degrees C using the classic (0.11<aw<0.96) and alternative methods (0.04<aw<0.92). The correlation between the isotherms obtained by the two methods was evaluated by comparing their simple linear regressions in which the Henderson linear model was fitted to the adsorption and desorption data (R20.99). Student's t-test showed that the angular and linear coefficients of the lines were statistically equal (p<0.05), indicating that the adsorption and desorption isotherms measured by the two methods were statistically the same. Therefore, the proposed alternative method can be used with excellent accuracy to measure sorption isotherms in cassava starch, and this alternative method can likely be used for other starchy products.