Comparison of different drying methods for bergamot peel: Chemical and physicochemical properties

This study examines the effectiveness of seven drying methods applied to bergamot peels, encompassing hot air, microwave, infrared-assisted microwave, freeze, infrared, sun, and oven drying. All samples exhibited moisture content and water activity levels within the acceptable range for dry foods. All methods effectively transformed the peels into powdered form, yielding comparable results. Each method offers distinct advantages and disadvantages, and the choice of method should be based on the desired properties of the final product. The highest ascorbic acid content was found in freeze-dried and hot air-dried samples (>400 mg/100 g), whereas sun-dried samples had the lowest (89.58 mg/100 g). Infrared-dried samples exhibited the highest levels of total phenolics and flavonoids (193.40 and 530.14 mg/100 g, respectively), attributed to reactions induced by elevated temperatures. The total carotenoids were higher in freeze-dried samples (54.12 mg/100 g) compared to other drying methods (<27 mg/100 g). Microwave-dried samples had the highest 5-hydroxymethylfurfural content (73.06 mg/100 g), and freeze-dried samples had the highest naringin content (1568.70 mg/100 g). Although infrared drying had good particle density, porosity, and fluidity, freeze-drying was the most effective, retaining the highest levels of bioactive compounds. Among the methods studied, freeze-drying is recommended due to its superior ability to preserve bioactive compounds. Infrared and infrared-assisted drying methods were suitable for recovering phenolics from bergamot waste, offering lower energy consumption and practical preservation of physicochemical properties. This study emphasizes the importance of selecting the appropriate drying method to ensure high-quality dried food and producing value-added products from bergamot waste, contributing to sustainable agriculture and waste reduction.