Oil distillation wastewaters from aromatic herbs as new natural source of antioxidant compounds

•Chemical and antioxidant profile of distillation wastewaters (DWWs) was evaluated.•Caffeic acid derivatives and flavonoid glycosides are the main DWWs constituents.•DWWs are rich in total phenolic compounds (TPC) and rosmarinic acid (RA).•Strong antioxidant properties of DWWs were related to TPC and RA levels.•DWWs are a new and cheap source of natural food additives or functional ingredients.

Distillation wastewaters (DWWs) are generated during the essential oil steam distillation from aromatic herbs. Despite of growing interest on novel source of natural antioxidant compounds as food additives, studies on DWWs are scarse. Herein, the potential of DWWs produced by the distillation of packaged fresh basil, rosemary and sage wastes was evaluated by chemical and antioxidant characterization.HPLC-DAD-HRMS profiling revealed that DWWs contain water-soluble phenolic compounds, mainly caffeic acid derivatives and flavonoid glycosides, with rosmarinic acid (RA) as predominant components (29-135 mg/100 mL). DWWs demonstrated high levels of total phenolic compounds (TPC, 152-443 mg GAE/100 mL) and strong antioxidant capacities, in ORAC, DPPH and ABTS assays (1101-4720, 635-4244 and 571-3145 μmol TE/100 mL, respectively). Highly significant correlations of TEAC values with TPC and RA contents revealed that phenolic compounds and high RA content were responsible of DWWs antioxidant properties.Thus, DWWs are proposed as a new promising source of natural food additives and/or functional ingredients for cosmetic, nutraceutical and food applications.

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