Effect of Chitosan Edible Coating and Thymus Essential Oil on Postharvest Life of ‘Shahroudi’ Table Grape

In this study, the effects of chitosan, Thymus essential oil and their combination on post harvest life and quality properties of grape (‘Shahroudi’ cultivar) were investigated. The study was conducted as a factorial experiment based on a completely randomized design with 3 replications. Grapes were treated by 0.5 and 1% (w/v)  chitosan solution, 150 and 300 µl/l Thymus essential oil their combination, and control fruits received no treatments. For combined  solution, chitosan treatments were first prepared, and then thymus essential oil was added to them. Grapes were packaged in 200 g packs and stored at 0-2°C and 90% ± 5 relative humidity for 90 days. Changes in weight loss, color, pH, total soluble solid (TSS), decay and sensory quality were measured each 10 days. Results showed that weight loss, pH, a*, decay, browning, shrivel and berry abscission increased during storage time. However TSS, firmness, L*, b*, color and flavor of berries decreased over the time. Chitosan and essential oil treatments significantly decreased weight loss, decay, color change, shrivel and berry abscission and increased flavor, color and quality of berries compared to control. According to the taste panelists, treated fruit by 1% chitosan + 150 µl/l thymus essential oil had better colour and taste than the others. Generally, chitosan, essential oil and their combination could increase grape pastharvest life and maintain their quality.