PH—Pastharvest Technology: Sorption Isotherms of Sweet Potato Slices

The equilibrium relative humidity of sweet potato slices with two drying temperatures and different histories were determined at temperatures ranging from 5 to 50°C. Estimated parameters, fitting ability, and predictive performance for five equilibrium relative humidity models were evaluated. The modified Halsey and modified Oswin equations were found to be adequate models to describe the equilibrium relative humidity data. In comparing the results of this study with previously published data, it was determined that the equilibrium relative humidity properties varied with species. Models from existing literature, detailing equilibrium relative humidity/equilibrium moisture content data for high-starch products (e.g. potato, cassava), were also examined. The Guggenheim–Anderson–de Boer (GAB) model was not an adequate model by checking residual plots. The parameters of the GAB model cannot be modified for prediction of the effect of temperature by the exponential function. For simplicity, an empirical linear model was developed to fit the equilibrium relative humidity/equilibrium moisture content data of sweet potato slices based on moisture content and temperature.