Improvement of Stilbene Content in Concord and Isabel Precoce Grapes and Juice through Methyl Jasmonate Application

In this research, the effect of methyl jasmonate (MJ) preharvest treatment was studied on grapes and their juice from two different regions. Concord and Isabel Precoce grapes from south and southeast Brazil received the treatment during two vintages (2017 and 2019). MJ preharvest treatment was able to increase stilbenes in the grape seeds and peels of Isabel Precoce in both regions. The juice elaborated with the treated grapes also has higher stilbene levels, especially piceid, that were detected even after 6 months of storage. Additionally, we performed a small study for this market niche; 189 consumers were interviewed, and it was observed that those with a higher frequency of grape juice consumption were willing to pay 25% more for grape juice with a higher resveratrol content. In conclusion, this work has evidenced the potential of MJ preharvest treatment to improve stilbenes in grapes and their juice, despite regional differences.