Performance and sustainability studies on solar tunnel and cabinet dryer for mango and jackfruit drying

• The drying performance of STD, SCD, and OSD was compared. • STD reduced drying time by 34.6–55.5% than OSD. • Drying efficiency was highest (14.3%) in STD for mango. • Quality analysis confirmed higher nutrient retention in STD and SCD. • SCD had lower CO 2 emissions (98.2 kg/year), making it more sustainable. Solar energy offers a sustainable and cost-effective alternative to conventional energy sources for agricultural drying applications. However, in many developing countries of tropical regions, the absence of efficient solar drying technologies leads to significant post-harvest loss. This type of losses mostly occurs in perishable fruits like mango and jackfruit remain a major challenge, primarily due to lack of proper drying practices. Traditional open sun drying often results in uneven drying, nutrient degradation, and microbial contamination. To address these limitations, a solar cabinet dryer (SCD) and a solar tunnel dryer (STD) were developed as sustainable alternatives for efficient fruit dehydration in rural settings. In the present study, two green energy dryers—a SCD and a STD—were developed at IIT Tirupati, India. The drying behaviour of mango and jackfruit was studied using both dryers, as well as the traditional open sun drying (OSD) method. The drying performance parameters, including the amount of water evaporated, drying rate, and drying efficiency, were estimated. For the STD, the amount of water evaporated, drying rate, and drying efficiency was 80.3 g, 26.17 g/hr, and 14.3 % for mango, and 66.9 g, 13.47 g/hr, and 13.4 % for jackfruit, respectively. In comparison, for the SCD, the amount of water evaporated, drying rate, and drying efficiency was 80.2 g, 25.40 g/hr, and 13.8 % for mango, and 66.8 g, 12.73 g/hr, and 12.4 % for jackfruit, respectively. Quality analyses of the two fruits dried using SCD, STD, and OSD were also performed. Compared to OSD, SCD retained 4.5–7.7 % more vitamin C, 3.4–4.0 % more protein, 0.9–2.1 % more carbohydrates, and 53.7–23.9 % more flavonoids. Similarly, STD retained 27.3–30.8 % more vitamin C, 10.2–12.0 % more protein, 2.0–2.6 % more carbohydrates, and 68.7–35.2 % more flavonoids than OSD. Among all methods, STD showed the highest nutrient retention, while OSD had the lowest. This suggests that the controlled drying conditions in the STD were more effective in preserving the nutrients of mango and jackfruit. The sustainability index of both dryers was found to be in the range of 1.14–1.65. The payback period for STD was longer than that for SCD for both mango and jackfruit drying. From the economic analysis, it was observed that the developed SCD holds significant potential for improving the livelihood of the farming community.