Search for a command to run...
Within Task T2.3.2, Terres Inovia investigated the thermal destruction and solvent extraction of glucosinolates (GSLs) from Brassica Carinata press cake, with the dual objective of (i) identifying mild processing conditions compatible with industrial constraints for feed applications, and (ii) producing GSL-rich extracts for biocontrol evaluation. Thermal treatments were first assessed on meal and press cake to reduce GSL content while preserving protein quality. Even under the most severe conditions tested (up to 120 °C, 25 min, intermediate moisture), total GSL reduction did not exceed about 45%, and was accompanied by a marked loss of protein solubility. These results highlighted the difficulty of achieving sufficient GSL destruction under mild conditions compatible with high-value feed uses. In parallel, a series of pilot- and lab-scale extraction trials was conducted to adapt a mustard-based biorefinery protocol to Brassica carinata. Extraction with hydroethanolic solvents (typically 50–60% ethanol, 40–50 °C) on press cake generated from mechanical pressing was optimised with respect to solvent composition, solvent-to-solid ratio, extraction time and percolation behaviour. Lab-scale experiments on milled press cake confirmed that near-quantitative recovery of GSLs is achievable when mass transfer limitations are minimised. However, pilot-scale percolation trials revealed (i) strong sensitivity of GSL extraction to press-cake structure and percolation quality, and (ii) incomplete GSL recovery (often ≤70%) even under extended extraction times and high solvent ratios. Additional lab work showed that diffusion limitations and poor bed irrigation could explain the residual GSL fraction in spent cakes. A second major finding concerns the role of myrosinase during extraction and concentration. Contrary to initial assumptions, myrosinase activity was shown to persist in 50% ethanol and to cause significant GSL hydrolysis when enzyme inactivation was incomplete. Heat treatments specifically designed to inactivate myrosinase (bench cooker and Spirajoule screw) reduced but did not always eliminate enzymatic degradation. Moreover, miscella concentration proved to be a critical step: under some vacuum-evaporation conditions, up to 30–60% of initially extracted GSLs disappeared from the liquid phase. Subsequent trials demonstrated that GSL losses during concentration depend on the combination of temperature, pressure (and thus ethanol content), and the presence of suspended enzymatic material. When extracts were clarified by centrifugation and concentrated at moderate temperature under appropriately controlled vacuum, GSL degradation could be almost completely avoided. Building on these insights, a new pilot-scale extraction protocol was implemented combining: (i) controlled thermal treatment for myrosinase inactivation, (ii) pressing conditions maximising oil removal and cell-wall disruption, (iii) an optimised hydro-ethanolic solvent system (higher ethanol content plus weak acidification) to favour GSL solubilisation while limiting enzymatic activity, and (iv) a more cautious concentration strategy. Despite these improvements, GSL extraction remained only moderately efficient at scale, mainly due to percolation and diffusion limitations inherent to industrial-type press cakes. A final production campaign was carried out in 2024 to supply crude GSL extracts to project partners for downstream purification and bioactivity testing. Several batches of carinata press cake were extracted at pilot scale and the miscellas concentrated prior to shipment. Overall mass balances indicated that roughly 40–45% of the initial GSLs could be recovered in the liquid extract, while a comparable fraction was hydrolysed and the remaining part stayed in the solid residue. The concentrated extracts obtained nonetheless met the quantitative needs of the receiving partners and provided a basis for assessing the biocontrol potential of carinata GSLs. In summary, the work conducted under Task 2.3.2 demonstrates that: (i) mild thermal treatments cannot simultaneously ensure deep GSL destruction and preservation of protein functionality in carinata meal; (ii) hydro-ethanolic extraction of GSLs from industrial-type press cakes faces both mass-transfer and enzymatic constraints; and (iii) miscella concentration is a sensitive step requiring careful control of temperature, ethanol content and solid removal. Although a robust, high-yield industrial process for GSL recovery from carinata could not be fully established within the project, the experimental data generated clarify the main technical bottlenecks and provide operational guidance for future process development and for the downstream partners who received pilot-scale extracts for further valorisation.