Improvements and Evaluation on Bitter Orange Leaves (Citrus aurantium L.) Solar Drying in Humid Climates

Dried, bitter orange leaves are widely used because of their nutritious and medicinal applications. As a result, many technologies have been used to accomplish its drying process. However, drying needs a long time and high energy demand, especially in humid climates. In this paper, bitter orange leaf drying was carried out using thermal and photovoltaic solar energy (integrated system, IS), eliminating the high humidity inside of the drying chamber to improve this process. A regular solar dryer (RD) was also used to compare the kinetics, mathematical modeling, and colorimetry study (as a quality parameter), evaluating both systems' performances. The drying leaves' weights were stabilized after 330 min in the RD and after 240 min in the IS, with a maximum drying rate of 0.021 kg water/kg dry matter center dot min, reaching a relative humidity of 7.9%. The Page and Modified Page models were the best fitting to experimental results with an Ra-2 value of 0.9980. In addition, the colorimetric study showed a better-preserved color using the IS, with an increment E of 9.12, while in the RD, the increment E was 20.66. Thus, this system implementation can reduce agroindustry costs by reducing time and energy with a better-quality and sustainable product, avoiding 53.2 kg CO2 emissions to the environment.

Automated summary

This study investigated the drying of bitter orange leaves using thermal and photovoltaic solar energy. The integrated system showed better performance in color preservation and drying rate compared to a regular solar dryer.