Effect of carrier agents on the physical and thermal stability of freeze-dried passion fruit (Passiflora edulis f. flavicarpa) pulp

Abstract

In this study, the physical and thermal stability of freeze-dried passion fruit (Passiflora edulis f. flavicarpa) pulp produced with different carrier agents was evaluated. Powders were produced using sucrose, fructose, ethanol, and maltodextrin as carrier agents and characterized by differential scanning calorimetry, morphology, moisture sorption curves, and sorption kinetics. The GAB (Guggenheim-Anderson-de Boer) model was suitable to mathematically describe the adsorption isotherms. The treatments that had maltodextrin as the additive exhibited reduced adsorption both in low- and in high-water activities, promoting the reduction of the moisture content in the monolayer (Xm) and enhancing the stability of the powder product. The combination of sucrose and ethanol increased the glass transition temperature of the system compared to the in natura pulp. Treatments with fructose did not improve the sorption characteristics of the powders, featuring an amorphous structure. The kinetic curves, ratio of the increase of the water content against the storage time, of the passion fruit pulp treated with 10 g of maltodextrin/100 g of pulp and with 5 g of sucrose and 10 g of maltodextrin/100 g of pulp showed reduced adsorption and similar behaviors for water activity values of 0.113, 0.529, 0.753, and 0.903.