Impact of solar drying methods on nutrient retention and microbial safety of dehydrated agricultural produce

Abstract:

How can solar-assisted dehydration systems be optimized to achieve maximum thermochemical efficiency for the preservation of seasonal fruits and vegetables in tropical climates? This research evaluated the thermochemical efficiency of solar-only and solar-assisted (hybrid solar-electric) dehydration systems for preservation of five seasonal products (mango, pineapple, tomato, pepper, okra) under tropical climatic conditions in Lagos, Nigeria. Thermal efficiency, specific energy consumption, drying rate, and moisture removal kinetics were determined. Solar-assisted hybrid systems achieved significantly higher thermal efficiencies (52.6–62.8%) compared to solar-only systems (36.7–46.2%) across all products (p < 0.05). Tomato exhibited the highest efficiency (62.8% hybrid; 46.2% solar-only), while okra demonstrated the lowest (52.6% hybrid; 36.7% solar-only). Drying time to reach safe moisture content (≤14% wb) was reduced by 28–38% with solar-assisted systems. Specific energy consumption ranged from 3.42 to 5.86 MJ/kg water removed. First-order drying kinetics confirmed that solar-assisted systems achieved 1.4–1.6-fold higher drying rate constants. These findings demonstrate that solar-assisted hybrid dehydration provides superior thermochemical performance for seasonal produce preservation.