Pulsed Electric Field Extraction and Antioxidant Activity Determination of Moringa oleifera Dry Leaves: A Comparative Study with Other Extraction Techniques

Abstract

The scope of this work was to determine the possibility of the application of the pulsed electric field (PEF) technique to the production of extracts from Moringa oleifera plant material (freeze-dried leaves). Various PEF conditions (pulse duration—PD; and pulse interval—PI) were tested. A field strength of 7 kV/cm was used. The total phenols in the extracts were evaluated by the Folin–Ciocalteu method and the antioxidant activity was evaluated by the radical scavenging activity (DPPH•), ferric reducing antioxidant power (FRAP) and Rancimat methods. The results were compared with those of the extracts obtained using other extraction techniques, namely microwave-assisted and ultrasound-assisted extractions, simple boiling water extraction, and plain maceration with water (as the control). The highest extraction of total phenols was achieved by the PEF procedure using 40 min treatment at a PD of 20 msec and a PI of 100 μsec. Additionally, all methods for the determination of the antioxidant activity showed that the activity of the extracts was proportional to the total phenol content. Concerning the PEF procedure, a low pulse duration with a high pulse interval is proposed in order to achieve higher extraction efficiency.

Enhancement of the Antioxidant, Anti-Tyrosinase, and Anti-Hyaluronidase Activity of Morus alba L. Leaf Extract by Pulsed Electric Field Extraction

“…Pretreatment with PEF has been reported to significantly increase the efficiency of betalain extraction from beetroot (P < 0.05) [11]. Additionally, a low pulse duration with a high pulse interval of PEF has been reported to increase the extraction efficiency of dry Moringa oleifera leaves [15]. PEF-assisted maceration of red grape juice also promoted wine color quality and the polyphenolic profile [16].…”

Should the in vitro colorimetric assays in antioxidant and lipid oxidation evaluation be abandoned? A critical review focusing on bioactive molecule screening assays in in vitro and in vivo models

“…Moreover, PEF treatment increased the extraction yield of polyphenols in tea leaves by two times compared to the conventional thermal methods without any significant changes in phenolic composition as evidenced by mass spectrometry analysis (Liu et al, 2019). Bozinou et al (2019) reported that the highest extraction yield in PEF treatment was found at a field strength of 7 kV/cm for 40 min in the extraction of phenolics from freeze-dried leaves of Moringa oleifera.…”

Pulsed Electric Field Extraction of α and β-Acids From Pellets of Humulus lupulus (Hop)

“…The PEF equipment used was provided by Val-Electronic (Athens, Greece), and included the static bench scale system, reported previously (Bozinou et al, 2019), accompanied by another high voltage power generator (from Eisco, India). The model of the batch processing chamber (TC) was adapted from a design of cylinder type electrodes (Ohshima and Sato, 2004) and consists of a coaxial stainless steel electrode [5 mm in diameter and 165 mm high, Figure 1(1)] placed inside a bronze cylinder [1 mm thick, 155 mm high and 30 mm outer diameter Figure 1(2)] with a closed flat bottom.…”

“…Conventional extraction methods require extended extraction times, high purity solvents, often offer low extraction selectivity and, finally, in some cases are responsible for the thermal decomposition of sensitive compounds (Bozinou et al, 2019). For the above reasons, new extraction techniques have been introduced.…”