This work compared the effects of pulsed electric fields (PEF) and ultrasound (US) technologies on the extent of cell disintegration of two Mediterranean herb tissues (Origanum vulgare L., Thymus serpyllum L.), as well as on the extractability of phenolic compounds during the subsequent hydroalcoholic extraction (0-50% ethanol in water, v/v) for up to 4h. The rate of phenolic compounds extraction decreased with time and was predicted rather satisfactorily (R 2 =0.898-0.989) by the Peleg's model. The application of either PEF or US treatment prior to solid-liquid extraction (SLE) has the potential to reduce duration and concentration of ethanol to achieve the same recovery yield of phenolic compounds. Under optimized PEF (3 kV/cm, 10 kJ/kg) and US (400 W, 20 min) treatment conditions, the extracts obtained from either PEF or US pre-treated herb samples showed higher total phenolic yield (36% on average) and antioxidant activity (FRAP) (36% on average) as compared to the control extraction, especially when 25% ethanol was used as a solvent. GC/MS analyses revealed no evidence of degradation of individual phenolics due to either PEF or US application.

The objective of this study was to evaluate the potential of green solvents for extractions of bioactive compounds (BACs) and essential oils from wild thyme (Thymus serpyllum L.) using theoretical and experimental procedures. Theoretical prediction was assessed by Hansen solubility parameters (HSPs) and conductor-like screening model for realistic solvents (COSMO-RS), to predict the most suitable solvents for extraction of BACs. An experimental procedure was performed by nonthermal technology high voltage electrical discharge (HVED) and it was compared with modified conventional extraction (CE). Obtained extracts were analyzed for chemical and physical changes during the treatment. Theoretical results for solution of BACs in ethanol and water, as green solvents, were confirmed by experimental results, while more accurate data was given by COSMO-RS assessment than HSPs. Results confirmed high potential of HVED for extraction of BACs and volatile compounds from wild thyme, in average, 2.03 times higher yield of extraction in terms of total phenolic content was found compared to CE. The main phenolic compound found in wild thyme extracts was rosmarinic acid, while the predominant volatile compound was carvacrol. Obtained extracts are considered safe and high-quality source reach in BACs that could be further used in functional food production.

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