Performance Evaluation of Evaporative Cooling Storage for Fresh Tomatoes in Kano State

This study evaluates the performance of brick-and-sand evaporative cooling structures for extending the shelf life of fresh tomatoes in Kano State, North West Nigeria. Fresh tomato shelf life at ambient temperature in northern Nigeria is only 3 to 5 days, creating significant post-harvest losses during peak production when market supply exceeds demand. Evaporative cooling, which exploits water evaporation through porous wall material to reduce storage temperature below ambient, offers a low-cost technology for extending fresh tomato shelf life without electricity. This study constructs a double-walled brick-and-sand evaporative cooling chamber at a tomato farmer group storage facility in Bunkure local government area. Performance is compared against ambient storage over 14-day trials during March and July, representing the peak production and dry season periods respectively. Storage temperature, relative humidity, tomato weight loss, colour change, firmness, and percentage marketable produce are measured every two days. Findings reveal that the evaporative cooler maintains temperature 8 to 12 degrees Celsius below ambient during dry season conditions, extending tomato shelf life from an average of 4 days in ambient storage to 10 days in the evaporative cooler. Marketable produce percentage at day 8 is 68 percent in the cooler versus 14 percent in ambient storage. The system construction cost is 45,000 naira for a 500-kilogram capacity chamber. The study concludes that evaporative cooling is a viable post-harvest technology for Kano tomato farmers and recommends community-scale cooperative cooler construction.

Keywords: evaporative cooling, tomato storage, post-harvest, Kano State, shelf life.