Moisture adsorption and tensile strength of pectin-pineapple juice films atdifferent relative humidities

This study evaluated the effect of different relative humidities (RH) (23%, 55%, and 75%) during storage on the stability against moisture adsorption and the strength of pectin-pineapple juice (P-PJ) films. The pectin-based films were added with various loading of pineapple juice (PJ). The static gravimetric technique determined the equilibrium moisture content (Me). Different storage relative humidities (RH) ranging from 11% to 90% were achieved using saturated salt solutions. The weight increase of PPJ films was measured for 7 to 14 days until equilibrium was established. The tensile strength was tested using a texture analyzer. The results showed that the different storage conditions significantly affected the film’s tensile strength. The film with 2 g PJ at 23% RH had the highest moisture adsorption and tensile strength (52.91±3.08 MPa) compared to other film formulations. The moisture adsorption isotherms of Peleg, GAB, and BET models were compared for their ability to best describe the experimental moisture sorption data with the highest goodness of fit (coefficient of determination, R2 ). The Peleg model was the most suitable data to fit the experimental data with the highest R2 of 0.9. The moisture sorption properties of the P-PJ films are important information to understand the changes in the films’ stability and strength due to the extent of exposure to relative humidity during storage.