Spouted bed drying parameters and adjuvant effects on polyphenol retention and antioxidant activity in mango peel powders

Abstract

The production of polyphenol-rich powders is a promising strategy for valorizing agro-industrial byproducts. This study evaluated drying yield, polyphenol retention, and antioxidant capacity of spouted bed drying, varying paste composition by adding silicon dioxide and corn starch as adjuvants and the temperature from 60 to 120°C. Drying yields ranged from 22.13% to 76.61%, influenced by temperature and the inclusion of colloidal SiO₂ and modified starch, which improved detachment from internal surfaces. Total polyphenol content varied from 0.76 ± 0.02 to 1.49 ± 0.20 mg of pyrogallol/g of powder, surpassing oven-dried peels (1.11 ± 0.01 mg/g) and fresh peels (1.01 ± 0.02 mg/g). At optimum operation conditions, temperature of 120°C and addition of 0.25 g of SiO₂ and starch per gram of peels, the operation showed a drying yield of 74.54%, water activity lower than 0.5, and significant polyphenols retention, 1.11 ± 0.03 mg of pyrogallol/g, of peels. Extracts from the powders exhibited strong antioxidant activity, with IC50 values from 35.95 to 92.95 μg/mL (DPPH assay), outperforming many fruits and vegetables. These findings highlight the potential of spouted bed drying combined with adjuvants to produce functional powders from mango peels, which may offer health benefits for humans and animals.