Effects of Hot Water, UV-C and Modified Coconut Oil Treatments on Suppression of Anthracnose Disease and Maintenance of Quality in Harvested Mango cv. ‘Chok-Anan’

Abstract

Anthracnose disease caused by Colletotrichum gloeosporioides Penz. is the major problem of harvested mango for domestic markets and for export. Control of anthracnose disease is currently based on the application of fungicides. However, it was reported that there are some chemical residues of chemical in mango and in the environment. Therefore, safe alternative methods for controlling anthracnose disease were studied. The aim of this experiment was to evaluate the antifungal properties of modified coconut oil (MCO) in vitro test and to investigate the combined effects of ethanolic shellac - modified coconut oil solution (ES-MCO), hot water (HW) and UV-C treatments on controlling anthracnose disease and maintaining postharvest quality of mango fruit cv. Chok-Anan (in vivo test). The antifungal activity of the MCO was determined by a paper disc method and tested the survival of MCO treated-fungal spores on PDA. The results revealed that 2% MCO significantly inhibited the mycelail growth of C. gloeosporioides on paper disc and completely killed fungal spore on PDA. In vivo test, harvested mangoes were cleaned with a solution of 100 ppm sodium hypochlorite and air dried. The fruit were treated with HW, UV-C followed by ES-MCO coating (HW + UV-C + ES-MCO), HW followed by UV-C (HW + UV-C), or ES-MCO alone. Untreated fruit served as the control. All fruit samples were then kept at 13°C for 15 days. HW + UV-C + ES-MCO treatments showed the most effective in reducing anthracnose disease, followed by HW + UV-C treatments, and ES-MCO treatment, while the control fruit showed the greatest symptoms of anthracnose disease. In addition, both the ES-MCO alone and the combined treatments of HW + UV-C + ES-MCO significantly delayed ripening of fruit by retarding firmness, weight loss, total soluble solids (TSS), titratable acidity (TA), ethylene production and respiration rate, while the peel and pulp color of mango fruit were maintained throughout the storage period. This founding shows that HW + UV-C + ES-MCO treatments may act as the safe alternative methods to suppress anthracnose disease and delayed the senescence of mango fruit during cold storage.