Improvement of grape phenolic content and antioxidant activity by pre-harvest application of methyl jasmonate

In this study the effect of pre-harvest methyl jasmonate (MJ) treatment, as a safe chemical elicitor in different concentrations (0, 1, 5, and 10 mM), of flavonoid (TFC), total tannin (TTC), and antioxidant activity were evaluated throughout 6 days storage. Although, MJ treatment stimulated an increase in TPC, TFC, and antioxidant activity during storage time, at the end of storage a reduction in their amounts was found. The interaction between MJ treatment and storage time was significant only for antioxidant activity measured by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay so that MJ treated-samples had higher radical scavenging ability on day 4 of storage. However, pre-harvest MJ treatment had no effect on TTC of skin samples during storage. These results suggested that pre-harvest treatment of MJ can be used as an environmentally friendly approach to enhance phenolic content and antioxidant capacity of 'Thompson Seedless' grape for a limited storage time.