Low-cost innovative food dryers for developing countries: current status and future prospect

Food drying is one of the most energy intensive processes in the food industry that consumes approximately 95 exajoule of energy globally. Moreover, the conventional thermal drying system using fossil fuels not only accounts for high amount of greenhouse gas emissions but also accounts for 15 % of the overall manufacturing process, approximately. In light of growing concerns over climate change and resource depletion, enhancing energy efficiency and promoting environmental sustainability in food drying technologies have become critical priorities. This study reviews the most promising low-cost innovative food drying techniques along with their limitations and future prospects. This study also explores the most common drying techniques such as, sun drying, solar drying, biomass drying, reversible air drying and heat pump drying, along with their shortcomings and advantages. Although sun drying is the cheapest method, poor food quality keeps the process from being implemented commercially. Among different low-cost innovative drying techniques, improved solar drying, geothermal drying, improved biomass drying, heat pump drying, waste heat-based convective drying (WHCD) and different hybrid drying, are compared due to their huge potentials to replace the conventional methods. This study reveals that although having some limitations involving improved solar drying and WHCD, they perform comparatively better having low environmental impact and improved efficiency. However, The findings underscore the need for comprehensive feasibility studies to enable the transition of these technologies from research to industrial-scale implementation, ultimately advancing the goal of sustainable and energy-resilient food systems.