Preservation of Postharvest Quality of Leafy Amaranth (Amaranthus spp.) Vegetables Using Evaporative Cooling

Abstract

Leafy vegetables are very highly perishable and must be utilized immediately after harvest. Their fast deterioration is attributed to various biological and environmental factors with temperature playing a central role. Evaporative cooling is a low-cost temporary storage technology that offers smallholder vegetable farmers an alternative to expensive cold rooms. The present study sought to determine the effectiveness of evaporative cooling using zero energy brick cooler (ZEBC) and evaporative charcoal cooler (ECC), to preserve the postharvest quality of leafy amaranth vegetables. Freshly harvested vegetables were separated into bundles weighing 300 grams and stored under ZEBC, ECC, and ambient room conditions (control). Real time changes in temperature and relative humidity (RH) as well as changes in quality attributes (physiological weight loss (PWL), wilting index, hue angle, and vitamin C) were determined during the storage period. The temperature difference between the ZEBC and ECC versus the ambient air ranged between 4 and 10°C. Significantly higher RH (80–100%) was recorded in both evaporative cooling chambers. At the end of storage, higher PWL (47.6%) was recorded at ambient room conditions compared to 10.5 and 6.7% under ZEBC and ECC, respectively. A rapid decline in vitamin C (51%) was reported in vegetables stored at ambient room conditions. Overall, there was better vegetable quality preservation under ECC and ZEBC.