Effect of Evaporative Cooling On Quality Attributes and Shelf Life of Tomato (Solanum Lycopersicum L.) – A Case of Desiccant Use

Abstract

The limited availability of proper storage facilities in developing countries is one of the main factors contributing to postharvest losses of horticulture fresh produce; thus new strategies and approaches are needed to reduce food losses and improve the sustainability and efficiency of the entire supply chain. This study aimed to assess the effectiveness of a desiccant evaporative cooling system on tomatoes’ quality and shelf life. Three evaporative coolers (with desiccant, without desiccant, and charcoal) were constructed and evaluated on their cooling efficiencies before being tested with tomatoes. The cooling efficiency of the evaporative cooler with desiccant was 87%, followed by the evaporative charcoal cooler (79.3%), and the evaporative cooler without desiccant with 67.2%. The incorporation of a desiccant (air preconditioning component) in an evaporative cooler increased its performance to provide a good environment (temperature and relative humidity) for fresh produce storage. It was then experimented on its effect on the quality attributes (physicochemical properties and microbial loads) of tomatoes during 20 days of storage. Open-field fresh three tomato varieties (Ansal F1, Bolgan F1, and Pendo F1) were harvested and brought immediately to the different storage conditions (desiccant evaporative cooler, evaporative charcoal cooler, and ambient room environment). Firmness, total soluble solids, weight loss, beta-carotene, total viable counts (TVC), and yeasts and moulds (YM) were analysed during storage to measure the quality and shelf life of the fruits. The firmness of the fruit was used to determine tomatoes’ shelf life. The results showed that the cooler with desiccant, the charcoal cooler, and the ambient are significantly different (P≤ 0.05) on all analysed parameters after 20 days of storage. The results were also affected by the variety of tomatoes whereby variety Pendo F1 had significantly (P≤ 0.05) high firmness of 2.79 Nmm-1, and Bolgan F1 had higher TSS (6.58 oBrix). Ansal F1 lost more weight (3.74%), and recorded more beta carotene (1.81 mg/100g), TVC, YM of 5.40 cfu/g, and 4.89 cfu/g, respectively. The mean shelf life of tomatoes was significantly (P≤ 0.05) longest in the desiccant evaporative cooler desiccant (61 days), followed by the evaporative charcoal cooler (37 days), and least in the ambient environment (24 days). The overall performance of the desiccant evaporative cooler was significantly higher (P≤ 0.05) than the evaporative charcoal cooler and ambient room storage. Therefore, using the desiccant evaporative cooler to preserve tomatoes can help reduce the postharvest losses of tomatoes, increasing food security. Keywords: Desiccant, evaporative cooler, cooling performance, tomato quality, shelf life