Experimental study reveals high hygroscopicity and temperature-dependent moisture sorption in foam-mat dried acerola pulp powder, indicating the necessity of moisture-barrier packaging.
Key Points
To evaluate the hygroscopic behavior, moisture sorption isotherms, and storage stability of acerola pulp powder produced using foam-mat drying.
Acerola pulp was foamed with an Emustab stabilizer and dried at 60 °C.
Fresh pulp and dried powder were evaluated for water activity, titratable acidity, reducing sugars, vitamin C, carotenoids, phenolics, and antioxidant activity.
Adsorption isotherms, hygroscopicity, caking, and solubility were determined at 10 °C and 25 °C across relative humidity levels of 20%, 50%, 70%, and 90%.
Foam-mat drying concentrated reducing sugars from 5.24% in fresh pulp to 45.49% in powder form.
The Oswin model best fitted the Type II sigmoidal isotherms (R² = 0.9921, mean relative error = 4.61% at 10 °C; R² = 0.9974, mean relative error = 3.27% at 25 °C).
Powder hygroscopicity ranged from 8.77 ± 0.72% to 53.39 ± 0.51%, exhibiting higher equilibrium moisture content at 25 °C due to high levels of low-molecular-weight sugars.