Effect of drying methods on sorption isotherms models of tree tomato powder

Sorption isotherms of tree tomato powder dried using solar tunnel (ST) and hybrid Innovative greenhouse solar dryer was studied at temperatures of 30, 40, and 50 °C, using a static gravimetric method. From the sorption isotherm, the equilibrium moisture content (EMC) increased with rise in water activity (aW). However, the values recorded for the Greenhouse dryer were consistently lower than those of the Solar Tunnel dryer at equivalent temperatures.
The evaluation of moisture sorption models was done, specifically focusing on the performance of the GAB, BET, Modified Halsey, Peleg, and Modified Oswin models, to shed light on the relationship between water activity (aW) and equilibrium moisture content (EMC) in the tree tomato powder products. Each model's predictive capabilities were assessed using the coefficient of determination (R²) and root mean square error (RMSE) metrics, revealing significant insights into their effectiveness in characterizing moisture behavior. Among the models tested, the GAB model emerged as the most reliable, exhibiting high R² values of 0.99 across all temperature conditions and low RMSE of 0.29, 0.35, and 0.34 at 30°C, 40°C, and 50°C respectively.