Control of Rhizopus soft rot and quality responses in plums (Prunus domestica L.) coated with gum arabic, oregano and rosemary essential oils

Abstract

This study evaluated the efficacy of coatings comprising gum arabic (GA) and essential oils from Origanum vulgare L. (OVEO) and Rosmarinus officinalis L. (ROEO) to control Rhizopus soft rot and quality of plums (Prunus domestica L.) during storage at room (25°C; 12 days) and cold (12°C; 24 days) temperatures. GA (1 mg/ml) and OVEO (0.25 μl/ml) or OVEO (0.06 μl/ml) plus ROEO (0.25 μl/ml) inhibited the mycelial growth, spore germination and sporulation of R. stolonifer. GA-OVEO and GA-OVEO-ROEO coatings delayed the occurrence of soft rot and decreased the rotted plums at the end of storage compared to GA alone. Plums coated with GA-OVEO and GA-OVEO-ROEO exhibited greater firmness decreased weight loss and lower decrease of sugars and phenolics at the end of storage compared to uncoated plums. GA-OVEO and GA-OVEO-ROEO coatings enhanced the color and flavor, while GA-OVEO coating affected negatively the aftertaste of plums. GA-OVEO-ROEO coating is a promising postharvest treatment for plums. Practical applications In plums, the reduction of postharvest quality losses resulting from decay caused by Rhizopus stolonifer contamination or by the ripening process is a major goal of postharvest technology, which increase attention to use environmental friendly methods as postharvest treatment of fruit. Edible coatings can reduce the use of synthetic fungicides, thus are in agreement with the increased consumer's demand by products obtained with the minimum quantities of synthetic products. Gum arabic is largely used in food industry, however underexplored as coating component, particularly in combination with natural antifungal substances such as essential oils. Edible coatings containing essential oils are considered environmentally friendly technologies because these substances when incorporated in polissacharydes can be released on surfaces of fruit and increase the storage time. This study evaluated coatings containing reduced amounts of oregano and rosemary essential oils in combination as postharvest treatment to control Rhizopus soft rot in plums (Prunus domestica), as well as their effects on the quality attributes of this fruit during storage. The tested coatings are presented as alternative technologies to control soft rot and preserve the quality of plums during storage.