Influence of drying processes on bioactive compounds profiles, hydroxymethylfurfural, color parameters, and antioxidant activities of Tunisian eggplant (<i>Solanum melongena</i>L.)
Moncef Chouaibi, Ahmed Snoussi, Samar Attouchi, Giovanna Ferrari
Abstract
In this study, different drying processes (hot-air convective drying, microwave drying, ultrasonically assisted convective drying, freeze-drying, and infrared drying) were applied to dry the eggplant slices. Therefore, the Newton (infrared drying), Page (hot-air convective drying, freeze-drying, and microwave drying), and modified Page (ultrasonically assisted convective drying) are the best models to describe the drying kinetics of eggplant slices. Furthermore, the effective moisture diffusivities (Deff) varied significantly from 1.16 × 10−10 (freeze-drying) to 3.31 × 10−8 m2/s (microwave drying) (p < .05). Besides, the highest and lowest activation energy values were observed in the samples treated with freeze-drying (38.80 kJ/mol) and ultrasonically assisted convective drying (23.87 kJ/mol), respectively. Moreover, the effect of the drying processes on the kinetic degradation and formation of bioactive compounds, HMF, enzymatic browning index, color parameters as well as on the antioxidant activity was investigated. Then, the Weibull model was proven be the best to better fit the polyphenols and flavonoids data. Novelty impact statement Five drying processes were applied to dry Tunisian eggplant slices. The ascorbic acid, anthocyanin, polyphenol and flavonoid amounts were determined during the drying of Tunisian eggplant slices. The freeze-drying process was selected as the best method to preserve the dried eggplant.