NMR METABOLOMICS OF BRASSICA VEGETABLES: PRACTICAL IMPLEMENTATIONS IN AGRO-FOOD SUSTAINABLE SYSTEMS

1H NMR based metabolite profiling in cruciferous crops has been developed [1,2] and up-dated practical implementations are strongly needed in the expanding and complex scenario of Brassica spp. vegetables. The present study focuses on the application of 1H NMR metabolomics to B. oleracea (cauliflower) and B. rapa subsp. sylvestris ("cime di rapa"/broccoli-raab/rapini) as a tool for resolving specific practical issues. In one case, the study aimed at by-product valorization (leaves, stems and florets) derived from cauliflower production in a perspective of recover and usage of bioactive compounds within a circular economy context [3]. A second study addressed the metabolic variation in leaves and florets of two rapini genotypes by comparing field harvested products (controls) against 4 day-long stored fresh and packaged products in order to valorize local vegetables and performance during shelf-life, and address genotype traceability [4]. Water-soluble metabolites from rapini tissues were extracted using methanol-water mixture (1:1 v/v), whereas both water- and lipo-soluble fractions were extracted from cauliflower (chloroform/methanol/water biphasic solvent system) by the Bligh-Dyer protocol [5]. Overall, water-soluble extracts of all tissue types from both vegetables prevalently contained over thirty metabolites of common classes (sugars, organic acids, free amino acids) though in different amounts based on tissue-specificity. Moreover, the assignment of several species-specific secondary metabolites was widened and refined by including glucosinolates and other sulfur-containing compounds. Finally, metabolic profiles - supported by chemiometric analysis (ANOVA and PCA) - showed that major differences were associated with organ diversity in rapini (leaves vs florets) and with the storage status (fresh vs packaged), while genotype divergences were less evident.