Microwave assisted fluidized bed drying of red bell pepper: Drying kinetics and optimization of process conditions using statistical models and response surface methodology

Abstract

Red bell peppers were dried by microwave assisted fluidized bed dryer at different drying conditions and the process was optimized using response surface methodology. The individual and combined effects of microwave power (180–540 W), air temperature (40–70 °C) and air velocity (15–20 m/s) were analyzed on the responses (ascorbic acid, total phenolic content, total flavonoid content, total carotenoid content, DPPH radical scavenging activity, rehydration ratio and total color change. The optimum values of the variables were 468.04 W microwave power, 60.14 °C air temperature and 16.82 m/s air velocity. The predicted amount of ascorbic acid content was 177.89 mg/100 g, total phenolic content 101.46 mg GAE/100 g DW, total flavonoid content 32.35 mg QE/100 g DW, total carotenoid content 7.00 mg/100 g, DPPH radical scavenging activity 82.80 (%), rehydration ratio 4.23 and total color change 20.87. Validation experiment was conducted at optimum conditions to confirm the suitability of the models.