Drying Kinetics and Quality Assessment of Lemon Peel Using Convective and Infrared Methods

Lemon peels are increasingly recognized for their diverse applications across various fields, including cleaning, food packaging, health, and energy. Their rich composition of citric acid and antioxidants makes them a valuable resource. Therefore, identifying an appropriate drying method for this product is crucial for maintaining its compounds and enhancing the shelf life of the product. This study aims to evaluate the influence of different drying techniques on the drying mechanism, color, appearance, and bioactive composition of lemon peels. An experimental study was conducted using two different methods: Convection drying (C) and infrared drying (IR) were performed at 50°C, 60°C, and 70°C. The results indicate that the most appropriate technique to preserve optimal color of lemon peels is infrared drying at a temperature of 50°C. Data analysis demonstrated that to achieve high levels of bioactive compounds, especially polyphenols and flavonoids contents, infrared drying at 50°C and 60°C was found to be optimal. Experimental data allowed the determination of moisture content and drying kinetics as a function of drying time. The bioactive compounds were analyzed before and after drying to evaluate the changes during the process. The samples dried at 50°C using infrared showed a maximum level of total polyphenols: 60.77 mg EGA/g DM, flavonoids: 0.22 mg EC/g DM, and an acidity of 2.53%. So, the use of infrared drying technique at 50°C is recommended.