The efficacy of a charcoal evaporative cooler in reducing post-harvest losses and preserving nutritional quality of okra among smallholder farmers in Arapai, Uganda.
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Date
2026
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Busitema University
Abstract
Post-harvest losses of perishable vegetables such as okra (Abelmoschus esculentus) remain a major challenge for smallholder farmers in Uganda's Teso sub-region, where losses are estimated at 30-50%. This study evaluated the effectiveness of a locally constructed charcoal evaporative cooler in reducing post-harvest losses and preserving the nutritional quality of okra. A Completely Randomized Design (CRD) with two treatments (charcoal cooler storage and ambient room storage) and three replications was used over a 14-day storage period. Environmental conditions like temperature, physical quality like weight loss and visual quality together with nutritional quality parameters like the phenolic content, antioxidant activity, chlorophyll content and ascorbic acid concentration was assessed at different intervals using standard methods for analysis. Data was analyzed using linear mixed models and the two way ANOVA with repeated measures at α=0.05. the results obtained indicated that the charcoal cooler reduced the internal temperature significantly with an average of 6.430c with it ranging between 5.01-7.170c compared to ambient conditions (F₁,₃₆ = 2456.78, p < 0.0001), hence keeping the temperature within the cooler in a small range of 20.34-22.020c compared to 24.99-27.920c in the ambient storage conditions. The okra stored in the cooler had lower weight loss of 27.49% compared to the ambient conditions that had 78.51% weight loss by day 14 and remained marketable for 9(nine) more days compared with only 3 (three) days under the ambient storage conditions. Nutritional quality was also better retained in the charcoal cooler: phenolic content (69.7% vs 29.6% at day 12; F₁,₂₀ = 198.45, p < 0.0001), antioxidant activity (76.0% vs 29.2% at day 12; F₁,₂₀ = 278.34, p < 0.0001), total chlorophyll content (65.0% vs 24.0% at day 14; F₁,₂₀ = 187.56, p < 0.0001), and vitamin C content (58.9% vs 14.7% at day 12; F₁,₂₀ = 212.34, p < 0.0001). a strong correlation of (r≥-0.932, p<0.01) was found between the physical and nutritional parameters, implying that weight loss weight reduction may serve as a nondestructive indicator for nutritional quality decline. Therefore the study concluded that a charcoal evaporative cooler is an effective and low cost alternative for reducing post-harvest losses while preserving the nutritional quality of okra. The shelf life was extended from 3 to 9days and in the same way improved the retention of bioactive. Evaporative coolers are suitable for smallholder farmers because of its low cost and availability of raw materials for construction, no electricity is required and its construction and maintains is cheap.
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Undergraduate research report
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Okello, C. (2026). The efficacy of a charcoal evaporative cooler in reducing post-harvest losses and preserving nutritional quality of okra among smallholder farmers in Arapai, Uganda. [Unpublished undergraduate research report]. Busitema University.