Development and validation of an indirect solar dryer for sour orange (Citrus aurantium) preservation and quality assessment

Resumen

Objective: To develop and validate a low-cost indirect solar dryer for the dehydration and preservation of sour orange (Citrus aurantium), assessing its thermal performance and impact on physicochemical and sensory properties under tropical climatic conditions.

Design/methodology/approach: A cabinet-type solar dryer was designed using locally available materials and tested in Orizaba, Veracruz, Mexico. The system incorporated natural and forced convection modes powered by a photovoltaic module. Drying experiments were conducted under three configurations and compared with an electric oven. Physicochemical parameters (pH, °Brix, titratable acidity, conductivity) and color metrics (CIELAB, ΔE, browning index) were analyzed. Efficiency, moisture removal, and environmental impact were evaluated.

Results: The solar dryer achieved relative drying efficiencies of 64–73%, with chamber temperatures between 37–47 °C and zero electrical energy consumption. Forced convection improved airflow and drying rate, reducing processing time by up to 29%. Physicochemical analyses indicated increased °Brix and variable acidity, while color changes were minimal in forced convection A (ΔE = 6.18). The system reduced CO₂ emissions by 1.31 kg per cycle compared to electric drying and lowered construction costs by approximately 83%.

Limitations on study/implications: Performance was evaluated under specific climatic conditions and for a single fruit type; broader validation across seasons and products is recommended.

Findings/conclusions: The indirect solar dryer represents a sustainable, low-cost alternative for food preservation, supporting SDGs 2 and 7 by reducing energy dependence and post-harvest losses. Forced convection enhances efficiency and quality retention, making the technology suitable for rural and small-scale agro-industrial applications.