Development of a Mobile Solar-Powered Cooling System to Extend Shelf Life of Jute Leaves

Abstract

Proper cooling systems are essential for preserving perishable agricultural produce and ensuring food security. However, in developing countries, inadequate cold storage results in significant spoilage, posing a threat to farmers’ income and food availability. Conventional refrigeration, in rural areas is energy intensive making sustainable alternatives necessary. Therefore, this study developed a Mobile Solar-powered Cooling System (MSCS) as renewable energy solution for perishable crops. The MSCS was built on a tricycle base with 550 W, 42.5 V, solar panel, 12 V, MPPT, charge controller, 12 V, 150 Ah deep-cycle solar battery, and Aglac ZH55G, 75 W, DC compressor using isobutane (R600a) refrigerant. The storage chamber, made of 60 mm polyurethane panels, housed stainless steel trays and racks for commodity storage. Jute leaves were sourced from Lasoju farms, Kwara State to evaluate the performance of the MSCS. A 2 by 3 factorial complete randomized design evaluated two storage conditions (ambient and MSCS) to monitor the effect of temperature and relative humidity on the quality and shelf life of jute leaves. The MSCS maintained an average storage temperature of 5 ± 4°C and relative humidity of 85 ± 10%, significantly improving the preservation of jute leaves compared to ambient conditions (average temperature: 30 ± 2°C) and fluctuating relative humidity of 65 ± 10%,. Key system metrics include a coefficient of performance (COP) of 2.02, indicating efficient energy use, with an average daily energy consumption of 1190 Wh. The system extended the shelf life of jute leaves to 11 days, compared to 4 days under ambient storage, jute leaves lost 80 and 8% of weight in 4 days for ambient and MSCS, respectively preserving essential nutrients such as Vitamin A (51.35 mg/100 g) and beta carotene (22.49 mg/100 g). Colour of test samples changed from deep green to yellow and dirty brown.  Microbial results for jute leaves under ambient storage was 3.8 x  cfu/g as against 1.0 x  cfu/g obtained for MSCS. This study established that controlled low-temperature, high-humidity environments enhance the shelf life of jute leaves. The system is recommended for stakeholders in vegetable supply chains especially in off grid areas.