Evaluation of Drying Parameters and Water Activity of Dried Banana for Improvement of Production

Drying is one of the unitary processes most used in the food industry but is still a complex and little-understood operation, especially regarding the selection and control of the process conditions to maintain end product quality. The drying curves for the dried banana slices were obtained using three different drying temperatures. Drying times of 51, 36, and 30 hours were required at temperatures of 50°C, 60 °C, and 70 °C, respectively, to achieve a moisture content of 23.5%. During the drying process, the water activity in the fruits was measured using the AQUALAB apparatus with direct reading. The exponential model was fitted to the experimental data using non-linear regression analysis. The coefficient of determination of the model was R 0.99. Water activity was determined throughout the drying process for the three treatments. The relationship between water activity moisture content and banana sorption isotherms content was studied. The data indicated that water activity decreased with drying time and increased with moisture content at all three temperatures. The sigmoid model was fitted to the experimental data by non-linear regression and the result of the fit was satisfactory (R2´0,995). The banana moisture content varied in function of the water activity and can be described by a four-parameter sigmoid polynomial model.