Sorption properties of cambuci (Campomanesia phaea O. Berg) untreated and pre-treated with sorbitol as osmotic solute

Sorption isotherms of sorbitol osmotically pre-treated cambuci slices were obtained at (40, 50, and 60) degrees C using DDI (dynamic) method. The curves were classified as type III and the fruits showed hydrophobic behavior at water activities (a(w)) lower than 0.4. The pre-treatment with sorbitol as osmotic solute resulted in changes in the sorption behavior indicating that this solute acts as a humidifier due to the water-binding property. The equilibrium moisture content (X-eq) was determined at (20, 30, and 40) % of relative humidity (RH). The results showed that the RH, pre-treatment and temperature significantly affected the X-eq (p < 0.05). In general, X-eq decreased at lower RH showing that a higher driving force contributes to larger water removal. The experimental data were fitted to BET, GAB, and zeta models that showed a good fit. The isosteric heat of sorption (Delta H-s) was calculated and reinforced the water-binding property of sorbitol as, for the same X-eq, the Delta H-s obtained by cambuci pre-treated samples were greater than by control ones.

Automated summary

The study investigated sorption isotherms of sorbitol osmotically pre-treated cambuci slices at different temperatures with the DDI method, finding that the fruits exhibited hydrophobic behavior at low water activities and the pre-treatment acted as a humidifier. Results showed that relative humidity, pre-treatment, and temperature significantly influenced the equilibrium moisture content, with X-eq decreasing at lower relative humidity, while the isosteric heat of sorption reinforced the water-binding property of sorbitol.