Use of Pulsed Electric Field as a Low-Temperature and High-Performance “Green” Extraction Technique for the Recovery of High Added Value Compounds from Olive Leaves

Olive leaves (OLL), an agricultural waste by-product, are considered a significant bioresource of polyphenols, known as bioactive compounds. This study evaluates the pulsed electric field (PEF) technique for the extraction of polyphenols from OLL. The study parameters included a series of “green” solvents (ethanol, water as well as mixtures of them at a 25% step gradient) and different input values for the pulse duration of PEF. The phytochemical extraction degree was evaluated using total phenol concentration (Folin–Ciocalteu method) and high-performance liquid chromatography (HPLC) analyses, while the antioxidant activity was assessed using differential scanning calorimetry (DSC). The results obtained from the PEF extracts were compared with those of the extracts produced without the PEF application. The highest PEF effect was observed for aqueous ethanol, 25% v/v, using a pulse duration of 10 μs. The increase in the total polyphenols reached 31.85%, while the increase in the specific metabolites reached 265.67%. The recovery in polyphenols was found to depend on the solvent, the pulse duration of treatment and the structure of the metabolites extracted.

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Optimization of Pulsed Electric Field as Standalone “Green” Extraction Procedure for the Recovery of High Value-Added Compounds from Fresh Olive Leaves

Antioxidants ◽

10.3390/antiox10101554 ◽

2021 ◽

Vol 10 (10) ◽

pp. 1554

Author(s):

Vasileios M. Pappas ◽

Achillia Lakka ◽

Dimitrios Palaiogiannis ◽

Vassilis Athanasiadis ◽

Eleni Bozinou ◽

...

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Pulse Duration ◽

Value Added ◽

Pulsed Electric Field ◽

Fine Tuning ◽

Olive Leaves ◽

Extraction Technology ◽

Extraction Chamber

Olive leaves (OLL) are reported as a source of valuable antioxidants and as an agricultural by-product/waste. Thus, a twofold objective with multi-level cost and environmental benefits arises for a “green” standalone extraction technology. This study evaluates the OLL waste valorization through maximizing OLL extracts polyphenol concentration utilizing an emerging “green” non-thermal technology, Pulsed Electric Field (PEF). It also provides further insight into the PEF assistance span for static solid-liquid extraction of OLL by choosing and fine-tuning important PEF parameters such as the extraction chamber geometry, electric field strength, pulse duration, pulse period (and frequency), and extraction duration. The produced extracts were evaluated via comparison amongst them and against extracts obtained without the application of PEF. The Folin-Ciocalteu method, high-performance liquid chromatography, and differential scanning calorimetry were used to determine the extraction efficiency. The optimal PEF contribution on the total polyphenols extractability (38% increase with a 117% increase for specific metabolites) was presented for rectangular extraction chamber, 25% v/v ethanol:water solvent, pulse duration (tpulse) 2 μs, electric field strength (E) 0.85 kV cm−1, 100 μs period (Τ), and 15 min extraction duration (textraction), ascertaining a significant dependence of PEF assisting extraction performance to the parameters chosen.

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Eco-Friendly Extraction and Characterisation of Nutraceuticals from Olive Leaves

Molecules ◽

10.3390/molecules24193481 ◽

2019 ◽

Vol 24 (19) ◽

pp. 3481 ◽

Cited By ~ 9

Author(s):

Cinzia Benincasa ◽

Ilaria Santoro ◽

Monica Nardi ◽

Alfredo Cassano ◽

Giovanni Sindona

Keyword(s):

Olive Tree ◽

Food Supplement ◽

Industrial Applications ◽

Added Value ◽

Green Solvents ◽

Olive Leaves ◽

Liquid Chromatography Tandem Mass ◽

Pharmaceutical Industries ◽

High Concentrations ◽

Extraction Power

Olive tree (Olea europaea L.) leaf, a waste by-product of the olive oil industry, is an inexpensive and abundant source of biophenols of great interest for various industrial applications in the food supplement, cosmetic, and pharmaceutical industries. In this work, the aqueous extraction of high-added value compounds from olive leaves by using microfiltered (MF), ultrapure (U), and osmosis-treated (O) water was investigated. The extraction of target compounds, including oleuropein (Olp), hydroxytyrosol (HyTyr), tyrosol (Tyr), verbascoside (Ver), lutein (Lut), and rutin (Rut), was significantly affected by the characteristics of the water used. Indeed, according to the results of liquid chromatography tandem mass spectrometry, the extracting power of microfiltered water towards rutin resulted very poor, while a moderate extraction was observed for oleuropein, verbascoside, and lutein. On the other hand, high concentrations of hydroxytyrosol were detected in the aqueous extracts produced with microfiltered water. The extraction power of ultrapure and osmosis-treated water proved to be very similar for the bio-active compounds oleuropein, verbascoside, lutein, and rutin. The results clearly provide evidence of the possibility of devising new eco-friendly strategies based on the use of green solvents which can be applied to recover bioactive compounds from olive leaves.

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Electrostrictive Grafr Elastomers and Applications

MRS Proceedings ◽

10.1557/proc-600-131 ◽

1999 ◽

Vol 600 ◽

Cited By ~ 26

Author(s):

J. Su ◽

J. S. Harrison ◽

T. L. St. Clair ◽

Y. Bar-Cohen ◽

S. Leary

Keyword(s):

Energy Density ◽

Electric Field ◽

High Performance ◽

Mechanical Energy ◽

Structure Property ◽

X Ray Diffraction ◽

Electromechanical Properties ◽

Scanning Calorimetry ◽

Polyurethane Elastomers ◽

New Class

AbstractEfficient actuators that are lightweight, high performance and compact are needed to support telerobotic requirements for future NASA missions. In this work, we present a new class of electromechanically active polymers that can potentially be used as actuators to meet many NASA needs. The materials are graft elastomers that offer high strain under an applied electric field. Due to its higher mechanical modulus, this elastomer also has a higher strain energy density as compared to previously reported electrostrictive polyurethane elastomers. The dielectric, mechanical and electromechanical properties of this new electrostrictive elastomer have been studied as a function of temperature and frequency. Combined with structural analysis using x-ray diffraction and differential scanning calorimetry on the new elastomer, structure-property interrelationship and mechanisms of the electric field induced strain in the graft elastomer have also been investigated. This electroactive polymer (EAP) has demonstrated high actuation strain and high mechanical energy density. The combination of these properties with its tailorable molecular composition and excellent processability makes it attractive for a variety of actuation tasks. The experimental results and applications will be presented.

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Increasing the Biogas Potential of Rapeseed Straw Using Pulsed Electric Field Pre-Treatment

Energies ◽

10.3390/en14248307 ◽

2021 ◽

Vol 14 (24) ◽

pp. 8307

Author(s):

Dawid Szwarc ◽

Katarzyna Głowacka

Keyword(s):

Electric Field ◽

Lignocellulosic Biomass ◽

Biogas Production ◽

Agricultural Waste ◽

Control Sample ◽

Pulsed Electric Field ◽

Waste Biomass ◽

Methane Fermentation ◽

Rapeseed Straw ◽

Pre Treatment

Due to the high availability of lignocellulosic biomass, which can be obtained from terrestrial plants, agricultural waste biomass, and the agro-food, paper or wood industries, its use for energy production by methane fermentation is economically and environmentally justified. However, due to their complex structures, lignocellulosic substrates have a low conversion factor to biogas. Therefore, scientists are still working on the development of new methods of the pre-treatment of lignocellulosic materials that will increase the biogas productivity from lignocellulosic biomass. The presented research focuses on the use of a pulsed electric field (PEF) to disintegrate rapeseed straw prior to the methane fermentation process. Scanning electron microscopy observation showed that, in the disintegrated sample, the extent of damage to the plant tissue was more severe than in the control sample. In the sample disintegrated for 7 min, the chemical oxygen demand increased from 4146 ± 75 mg/L to 4920 ± 60 mg/L. The best result was achieved with a 5-min PEF pre-treatment. The methane production reached 290.8 ± 12.1 NmL CH4/g VS, and the biogas production was 478.0 ± 27.5 NmL/g VS; it was 14% and 15% higher, respectively, compared to the control sample.

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Pulsed Electric Field and Salvia officinalis L. Leaves: A Successful Combination for the Extraction of High Value Added Compounds

Foods ◽

10.3390/foods10092014 ◽

2021 ◽

Vol 10 (9) ◽

pp. 2014 ◽

Cited By ~ 1

Author(s):

Vassilis Athanasiadis ◽

Achillia Lakka ◽

Dimitrios Palaiogiannis ◽

Vasileios M. Pappas ◽

Eleni Bozinou ◽

...

Keyword(s):

Electric Field ◽

Volatile Compounds ◽

Pulse Duration ◽

Pure Water ◽

Value Added ◽

Pulsed Electric Field ◽

Salvia Officinalis ◽

Pure Ethanol ◽

Assisted Extraction ◽

Salvia Officinalis L

The present study aimed to evaluate the pulsed electric field (PEF)-assisted extraction of phytochemicals from Salvia officinalis L. leaves. The study parameters included a PEF pulse duration of 10 or 100 μs for 30 min, using different “green” extraction solvents: pure ethanol, pure water, and their mixtures at 25, 50, and 75% v/v concentrations. The resulting extracts were evaluated against reference extracts obtained without PEF. For estimation of the extraction efficiency, the content in total polyphenols, individual polyphenols, and volatile compounds, as well as the resistance to oxidation, were determined. The optimal PEF contribution on the total and individual polyphenols, rosmarinic acid, extractability (up to 73.2% and 403.1% increase, respectively) was obtained by 25% v/v aqueous ethanol solvent using a pulse duration of 100 μs. PEF was proven to also affect the final concentration and composition of volatile compounds of the extracts obtained.

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Impact of Pulsed Electric Field on Glycerin Sedimentation from Biodiesel Production Process

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.846.262 ◽

2020 ◽

Vol 846 ◽

pp. 262-266

Author(s):

Thanadol Hinthao ◽

Tanakorn Wongwuttanasatian ◽

Amnart Suksri

Keyword(s):

Electric Field ◽

Pulse Duration ◽

Applied Voltage ◽

Glass Tube ◽

Pulsed Electric Field ◽

Field Method ◽

Reaction Chamber ◽

Biodiesel Production ◽

Molar Ratio ◽

The Impact

This research aims to study the impact of continuous pulsed electric field (PEF) on glycerin separation from Transesterification process. Transesterification process of biodiesel production using 100 ml vegetable oils with alcohol of 1:5 molar ratio together with potassium hydroxide (KOH) as catalyst 1 wt.% for the reaction. The designed glass tube reaction chamber is 250 ml contained with coaxial cylindrical electrodes. The applied voltage to an electrode was at 1 kV and frequency of 1 kHz with pulse duration of 500 μs and also 4 kHz with pulse duration of 125 μs. The results showed that the glycerin volume from transesterification process has rapidly sedimented with pulsed electric field method. It is much faster than using conventional gravity method. The sedimentation rate increases rapidly with an increasing in frequency of the applied voltage. The highest volume of glycerin sedimentation of 10.2 ml is by using pulsed electric field at 1 kV and 4 kHz.

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

Beverages ◽

10.3390/beverages5010008 ◽

2019 ◽

Vol 5 (1) ◽

pp. 8 ◽

Cited By ~ 10

Author(s):

Eleni Bozinou ◽

Ioanna Karageorgou ◽

Georgia Batra ◽

Vassilis G. Dourtoglou ◽

Stavros I. Lalas

Keyword(s):

Antioxidant Activity ◽

Electric Field ◽

Pulse Duration ◽

Moringa Oleifera ◽

Pulsed Electric Field ◽

Pulse Interval ◽

Total Phenols ◽

Extraction Techniques ◽

Antioxidant Power

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.

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