Total phenolic content and antioxidant capacity of Greek medicinal and aromatic plant extracts using pulsed electric field followed by ultrasounds extraction process

The aim of this study was to evaluate an advanced water extraction method applying pulsed electric field followed by ultrasound. For this purpose, antioxidant capacity (AC) and total phenolic content (TPC) of Olea europaea L. leaves and unripe fruit, Melissa officinalis L. leaves, Cistus incanus L. ssp. creticus leaves, Vitis vinifera L. cv. “Xinomavro” leaves, marc, and fruits, Aronia melanocarpa L. fruits, Punica granatum L. peel, and Crocus sativus L. petals were analyzed. The results showed that a ratio of 1/20 g plant material/ml water, 5 min pulsed electric field and 30 min ultrasounds presented the maximum extraction efficiency. Melissa officinalis L. and Punica granatum L. had high TPC exhibiting 155 mg GAE/g DW (DW: dry weight) and 208 mg GAE/g DW, respectively, comparing to Vitis vinifera L. marc (31 mg GAE/g DW). All aqueous extracts studied, had high AC approaching 90% (except 32% in Crocus sativus L. petals and Vitis vinifera L. marc). Practical applications The beneficial use of medicinal and aromatic plants extracts in human health has been widely accepted. However, the efficiency of the process for the extraction of phenolic compounds from plants constitutes a challenge, since it is highly depended on the applied technique itself and the imposed operating conditions. In this regard, this work studies the application of a novel combined process of pulsed electric field extraction followed by ultrasounds assisted extraction for the recovery of polyphenols from selected Mediterranean plants. The evaluated process showed high extraction yields at short processing time and at moderate temperatures, which in conjunction with the use of water as a “green” extraction solvent lead to bioactive compounds stability and increased applicability of aqueous extracts.