Methyl Jasmonate Treatment Enhances Glucosinolate Content of Cauliflower Heads without Influencing Postharvest Quality, Poster Board #145

Previous reports indicate that spray treatments of methyl jasmonate (MeJA) can significantly increase glucosinolate concentrations in brassica vegetables and putatively enhance anticancer bioactivity. However, there is little information about the effect of MeJA treatments on the post-harvest quality of cauliflower. To address this, cauliflower heads in replicated field plots were sprayed with either 0.1% Triton-X (controls) or 500 µM MeJA solutions (containing 0.1% Triton-X) four days prior to harvest, then heads stored at 4 °C and 20 °C. Subsamples of head tissues were collected after 2, 4, and 5 days of storage at 20° C and after 10, 20, and 30 days of storage at 4 °C and assayed for visual color, CO₂and ethylene production, glucosinolate and total phenolic concentrations, tissue antioxidant activity by the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)(ABTS) assay, and anticancer bioactivity by the quinone reductase (QR) assay. The MeJA treatment of cauliflower increased head tissue glucoraphanin, glucobrassicin, and neoglucobrassicin concentrations by 1.5, 2.4, and 4.6 fold over controls, respectively, but had no significant effect on total phenolics. MeJA treated cauliflower showed higher QR activity compared to controls stored at both 4 °C and 20 °C. Total phenolics and tissue antioxidant activity (ABTS) in both treated and control cauliflower gradually increased during postharvest storage, with a greater increase at 4 °C than at 20 °C. There were no differences between the treatment groups for visual color measured by Hunter’s colorimeter or for CO₂ or ethylene gas production. In conclusion, MeJA treatments were observed to enhance the putative health-promoting properties of cauliflower without a detrimental effect on the maintenance of postharvest quality.