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The potential of high voltage electrical discharge for extraction of bioactive compounds from rosemary (Rosmarinus officinalis L.)

Rosemary (Rosmarinus officinalis L.) is a Mediterranean medicinal and aromatic plant widely used due to it's valuable bioactive compounds. In this study, high voltage electrical discharge (HVED) was used for recovery of intracellular compounds from dried rosemary leafs. HVED is an innovative non-thermal extraction method, efficient, sustainable and has improved extraction yield, when compared to conventional extractions. The optimal HVED parameters were as follows: frequency 100 Hz, pulse width 400 ns, gap between electrodes 15 mm, liquid to solid ratio 50 mL/g, voltage 15 and 20 kV for argon and 20 and 25 kV for nitrogen gas. Green solvents were used, water and ethanol (25% and 50%). The comparison was done with untreated samples, which were extracted by light stirring with same parameters as HVED treatment. The obtained extracts were analysed for total phenolic compounds (TPC), antioxidant activity (DPPH and FRAP) and NIR spectroscopy. NIR spectroscopy was recorded with spectra over a wavelength range of 899-1699 nm. Two significant ranges were identified, 904-932 nm and 1349-1699 nm. HVED extraction showed higher yields for the extraction of bioactive compounds, 2.09x for TPC and 2.34x for FRAP, compared with untreated samples. Longer treatment time, higher voltage and ethanol content yielded higher phenolic content in HVED extraction, and it was higher for treatment with nitrogen than argon, which was also confirmed by DPPH. For correlation purposes, the principal component regression (PCR) was conducted for NIR ranges 904-1699 nm in prediction of TPC, DPPH and FRAP. Obtained PCR models were applicable with high R2 and Radj values and confirmed the idea of NIR spectra usage for quantification of bioactive compounds in rosemary extracts treated with HVED. These results demonstrated that HVED could be an efficient method for extraction of bioactive compounds from rosemary which could be used for functional food application.

Rosemary ; High voltage electrical discharge ; Sustainability ; Bioactive compounds

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