Influence of drying processes on bioactive compounds profiles, hydroxymethylfurfural, color parameters, and antioxidant activities of Tunisian eggplant (Solanum melongenaL.)

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.

Ultrasound‐assisted vacuum drying as alternative drying method to increase drying rate and bioactive compounds retention of raspberry

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The effect of drying methods on the color, chlorophyll, total phenolic, flavonoids, and macro and micronutrients of thyme plant

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The impact of drying methods on quality parameters of purple basil leaves

“…and chi-square (χ 2 ) were calculated using the following equations, respectively (Alibas et al, 2020;Chouaibi et al, 2021).…”

“…For each fresh and dried sample, color measurements were read 10 times. The equations that were used for the color change, whitening index, and browning index calculated in relation to L, a, and b values were as follows (Barman et al, 2021;Chouaibi et al, 2021;Cuccurullo et al, 2018).…”