Risk assessment of replacing synthetic preservatives with natural ingredients

The present work, developed within the EU-FORA fellowship programme, assessed the risk assessment of vegetable by-product extracts as natural alternatives to synthetic preservatives in food formulations. Extracts were obtained from onion peel (<i>Allium cepa</i> L.), zucchini (<i>Cucurbita pepo</i> L.) and kale (<i>Brassica oleracea</i> L. var. <i>acephala</i>), which represent abundant residues with limited commercial value but high potential for valorisation. Suitable extraction techniques were applied to each matrix, and the resulting extracts were characterised through phenolic profiling, antioxidant activity, cytocompatibility and pesticide residue analysis. Onion peel extract was rich in quercetin glycosides and showed strong antioxidant activity, while zucchini and kale extracts contained quercetin or kaempferol derivatives with moderate effects. Cytocompatibility assays demonstrated acceptable safety margins at lower concentrations, though dose-dependent toxicity appeared at higher levels, particularly in hepatic cells. Pesticide residues were mostly absent or present only at trace levels in zucchini and kale extracts. In onion peel extract, hexachlorobenzene and β-HCH were detected, but remained below EU maximum residue limits (MRLs). Overall, the findings suggest that the benefits of these extracts, including preservative potential and sustainable waste valorisation, outweigh the identified risks.