Effect of drying temperatures and storage on chemical and bioactive attributes of dried tomato and sweet pepper

Abstract

In this study tomato (Punjab Ratta) and sweet pepper (Indira) were subjected to three different drying temperatures (40, 50 and 60 °C) to examine the effect of drying temperatures and storage period (180 days) on the chemical and bioactive parameters of dried tomatoes (T) and sweet peppers (SP). The drying of T and SP at 60 °C results in better retention of phenolics (738.44 ± 0.10 and 593.78 ± 0.09 mg/100 g db), antioxidant activity (42.79 ± 0.11 and 27.56 ± 0.07%) and flavonoids (499.56 ± 0.04 and 286.31 ± 0.07 mg/100 g db), respectively however chemical parameters significantly (p < 0.05) decreased at 60 °C except for lycopene. Better retention of color was observed in T samples dried at 60 °C and SP samples dried at 40 °C. Storage studies revealed that powders retained polyphenols in T (736.88 ± 0.08 mg/100 g db) and SP (591.85 ± 0.09 mg/100 g db) even after 90 days of storage that were dried at 60 °C. Significant loss of chemical and bioactive constituents was observed in stored samples dried at 40 °C due to high initial water activity of T (0.562 ± 0.02) and SP (0.611 ± 0.01) powders. This study concluded that samples dried at a higher temperature (60 °C) showed effective retention of the bioactive components after drying and during the storage period.