Evaluation of the effect of pre-harvest foliar application of chitosan and thymol coating on the quality and storage life of strawberry (Fragaria × ananassa Duch.) fruit 'Parus' cultivar

Post-harvest waste of strawberry fruit is high due to its high sensitivity to fungal agents and has caused a very short development of this valuable and useful fruit. On the other hand, the use of synthetic antifungal chemical compounds to increase the shelf life of this fruit has caused many concerns. For this reason, it is necessary to use safe methods to control spoilage and maintain the quality of strawberry fruit during storage. Today, the use of natural antimicrobial essential oils in oral coatings has attracted the attention of consumers. The essential oil of thyme has a great antibacterial, antifungal and antioxidant effect.

This study was performed as a factorial experiment in a completely randomized design with three replications in the research greenhouse of the Faculty of Agriculture, Lorestan University. The first factor is the type of material with different concentrations in five levels including 0, 0.3%, 0.6%, the combination of chitosan with thymol 0.3 % and 0.6 % and the second factor is the storage time in four levels including 0, 9, 18, It was 27 days after storage. Harvested fruits at 4 ° C with a relative humidity of 90±5 and parameters such as weight loss, pH, fruit firmness, acidity (TA), soluble solids (TSS) and taste index, vitamin C, Phenol and flavonoids, fruit shelf life (number of days) during storage, were studied.

The results of analysis of variance showed that the effect of treatment type and storage time on all studied traits was significant at the level of one percent probability. Fruits treated with chitosan and thymol 0.3% and 0.6% had higher tissue firmness, vitamin C, taste index, phenolic substances and soluble solids content and better durability than the control. In all four measurement times, the highest content of phenol, vitamin C and tissue stiffness was related to chitosan and thymol treatment of 0.3 and 0.6 % and the lowest was related to the control. Fruit tissue firmness gradually decreased during storage, but this trend was observed at a significantly slower rate in treated fruits.

Considering the increase of 7 and 9 days after harvest of combined treatment of chitosan and thymol 0.3 % and 0.6 % in comparison with other treatments and control, therefore, pre-harvest application of chitosan and application of edible coating thymol can be recommended as a safe and low cost strategy to increase the postharvest life of strawberry cultivar 'Parus'.