Kinetics of Antioxidant Activity and Color Degradation in Tomatoes during Hot Air Drying

Abstract

The antioxidant activity (AA) and color degradation were monitored in tomato quarters (Rio Grande) during hot air drying in a cabinet drier at five temperatures (60, 70, 80, 90 and 100°C) at an airflow rate of 0.2 m/s and 20% relative humidity. AA values of fresh tomatoes determined by total phenolic content (TPC), FRAP and DPPH assays were 85.3 mg GAE, 26.2 µmol TE and 31.3 µmol TE/100g dm, respectively. Increasing drying temperature resulted in a reduction in Hunter Lab and a/b color values of tomatoes as well as their AA values. During hot air drying, the degradation of AA and color values of tomatoes followed a first-order reaction. Activation energy values for AA degradation determined by TPC, FRAP and DPPH assays were 24.36, 22.91 and 23.67 kJ/mol, respectively. High correlations were found among the TPC, DPPH and FRAP values and lycopene and β-carotene contents of tomatoes during hot air drying. Degradation kinetic data revealed that color values and tomatoes AA are susceptible to drying temperature. © 2023 The Author(s).