Beneficial effects of rosemary, thyme and tarragon essential oils on postharvest decay of Valencia oranges

Abstract

Background: Increasing restrictions on pesticide application in the production process of agricultural food products indicate urgent need for safer alternatives to keep the product quality, and to inhibit pathogen infections. In the present study, effect of three essential oils from rosemary, thyme and tarragon, in concentrations of 500 and 1000 ppm, were evaluated on shelf life and postharvest decay of Valencia oranges and under laboratory conditions. Valencia fruits were inoculated with or without crushing the fruit peel surface with the blue mold fungi (Penicillium italicum). The extent of decay and some quality parameters were evaluated during 4 weeks. Results: When inoculation was performed with peel surface crushing, all fruits were fully decayed after 1 week, and only fruits in control (without infection) remained intact. However, when fruits were inoculated by just submerging and without peel crushing, depending on applied oil sources and oil concentrations, significant reduction in fruit decay was observed. Tarragon and thyme essential oils in both concentrations reduced the fruit decay; however, their 1000 ppm rather than 500 ppm was more effective on preventing fruit decay. Rosemary essential oil was less effective than the other two essential oils on preventing orange decay by blue mold fungi. Conclusions: Tarragon and then thyme oils were most effective on preventing fruit decay and can be effectively used during postharvest handling and storage to keep Valencia orange fruits out of decaying.[Figure not available: see fulltext.].