Nadia Boussetta

Electrically assisted extraction of soluble matter from chardonnay grape skins for polyphenol recovery.

The objective of this study was to investigate the effects of pulsed electric field (PEF) and high-voltage electrical discharges (HVED) application on the efficiency of aqueous extraction of total soluble matter and polyphenols from grape skins ( Vitis vinifera L.) at different temperatures within 20-60 degrees C. The highest level of polyphenol concentration C was reached after about 60 min of extraction for HVED treatment: C(HVED) = 21.4 +/- 0.8 micromol of gallic acid equivalent (GAE)/g of dry matter (DM). Almost the same level of C was reached after 180 min of extraction for the PEF-treated skins. These levels exceeded the value C = 19.1 +/- 0.5 micromol of GAE/g of DM for the untreated samples. The difference between degrees Brix values for HVED-treated and untreated systems decreased with temperature increase (from 40 to 60 degrees C), but a large difference in the total amount of polyphenols was observed for HVED-treated and untreated systems. The activation energies were W(u) = 31.3 +/- 3.7 kJ/mol and W(PEF) = 28.9 +/- 5.5 kJ/mol for untreated and PEF-treated systems, respectively.

Effect of Alternative Physical Treatments (Ultrasounds, Pulsed Electric Fields, and High-Voltage Electrical Discharges) on Selective Recovery of Bio-compounds from Fermented Grape Pomace

The aim of this study is to compare alternative treatments on solvent-free extraction of high added value components from fermented grape pomace. Ultrasounds (US), pulsed electric fields (PEF) and high voltage electric discharges (HVED), which are physical treatments able to induce cell damages, were applied on aqueous suspensions of grape pomace. The efficiency of these technologies for phenolic compounds extraction, and particularly for anthocyanins recovery, was evaluated throughout the treatments at equivalent cell disintegration indexes (Z). HVED proved to be the most interesting technique to achieve higher phenolic compounds recovery with lower energy requirement than PEF and US at the same values of Z. However, HVED was less selective than PEF and US regarding the amount of anthocyanins recovered. At equivalent cell disintegration of Zu2009=u20090.8, PEF remarkably increased the extraction yield of total anthocyanins up to 22 and 55xa0% in comparison with US and HVED-assisted extractions. At this Z value, the ratio of total anthocyanins to TPC extracted reaches the respective values of 41.7, 34.9 and 14.1xa0% for PEF, US and HVED, thus demonstrating interesting differences of selectivity of the treatments.

Application of Non-conventional Extraction Methods: Toward a Sustainable and Green Production of Valuable Compounds from Mushrooms

Mushrooms are a great source of nutritionally valuable compounds, including proteins, lipids, polysaccharides, polyphenols, micronutrients and vitamins. In particular, they are a significant dietary source of B group vitamins and can be an ideal vehicle in order to supply these vitamins for vegetarians. Conventional extraction methods usually involve water or organic solvents and may results in the noticeable degradation of components. This review describes the potential use of the novel non-conventional methods including enzyme-assisted extraction, pulsed electric fields, ultrasounds, microwaves, subcritical and supercritical fluid extraction for recovery of valuable compounds from mushrooms. Recent studies have shown the great potential of these environmentally friendly methods for green production of specific compounds for use as nutraceuticals or as ingredients for functional foods.

Impact of pulsed‐electric field and high‐voltage electrical discharges on red wine microbial stabilization and quality characteristics

In this study, pulsed‐electric fields (PEF) and high‐voltage electrical discharges (HVED) are proposed as new techniques for the microbial stabilization of red wines before bottling. The efficiency of the treatment was then evaluated.

Pulsed Electrical Technologies Assisted Polyphenols Extraction from Agricultural Plants and Bioresources: A Review

The application of pulsed electrical technologies such as high voltage electrical discharges (HVED) and pulsed electric fields (PEF) have been currently proposed for promoting biocompounds extraction. Even if their principles of action are different, both of these techniques have shown to be efficient for the enhancement of polyphenols extraction from different raw materials as compared to control extraction. Depending on the product, the energy consumption, the cell disruption, the polyphenols composition, the extraction and purification steps are different when applying PEF or HVED. This paper thus reviews the current status of research on the application of HVED and PEF for extraction and purification of polyphenols from plants.

Effect of ultrasound and green solvents addition on the oil extraction efficiency from rapeseed flakes

The current procedure of rapeseed oil extraction is based on a first extraction step by pressing followed by a second extraction step with hexane. This solvent being toxic for the users, the consumers and the environment, its use could be forbidden within the coming years. Stimulated by a stringent regulation, the research activity for the replacement of toxic solvents shows a significant development. The aim of this study was to select alternative solvent to hexane such as ethanol or isopropanol, and, to adjust the oil extraction process by developing an ultrasound assisted method. The objective was to reach a comparable efficiency but also to enhance the oil quality. When applied to isopropanol, the ultrasound assisted extraction method has shown promising results, and comparable to those obtained with hexane (oil yield of 80% for hexane and 79% for isopropanol at optimum extraction conditions (20min of ultrasound pretreatment followed by 2h of additional solid/liquid extraction)). Conversely, in studied conditions, ethanol did not seem to be an appropriate alternative solvent to hexane as the extraction yields obtained by using this solvent were quite low.

Innovative physically-assisted soda fractionation of rapeseed hulls for better recovery of biopolymers

A better knowledge of the effect of non-conventional pretreatment technologies, which can avoid the use of high temperatures and detrimental solvents, is necessary. Thus, physical pretreatment (ultrasounds (US), microwaves (MW), high voltage electrical discharges (HVED) and pulsed electric fields (PEF)) were applied in order to evaluate their effects on acid insoluble residue removal and enzymatic hydrolysis yields from rapeseed hulls. The subsequent chemical treatment consisted of adding 0.3 mol L−1 of hydroxide sodium and maintaining the suspension at 60 °C for 2 h. The results showed that applying physical pretreatments resulted in an increasing yield of acid insoluble residue by 5% (PEF), 6% (MW), 8% (HVED), 12% (US) respectively, in comparison with the chemical treatment. The pulps isolated by physical-assisted extraction, showed a higher enzymatic digestibility. The results obtained in the present study confirm that coupling pretreatments constitute a promising alternative for the valorization of this by-product.

High voltage electrical discharges combined with enzymatic hydrolysis for extraction of polyphenols and fermentable sugars from orange peels

Orange peels are a biomass rich in carbohydrates and polyphenols and characterized by their low lignin content. This work focuses on finding the best combination between physical and biological treatments to enhance the extraction of fermentable sugars and polyphenols. High voltage electrical discharges (HVED) (0 to 900u202fkJ/kg) or enzymatic hydrolysis with Viscozyme® L (12u202fFBGU/g) were applied on fresh or defatted orange peels for the extraction of polyphenols and fermentable sugars. An HVED energy input of 222u202fkJ/kg was optimal for the extraction of reducing sugars (19u202fg/100u202fg DM) and polyphenols (0.7u202fg/100u202fg DM). However, enzymatic hydrolysis allowed a higher extraction of reducing sugars (50u202fg/100u202fg DM). HVED were then applied prior or simultaneously to enzymatic hydrolysis to maximize the extraction of biomolecules from orange peels. Thus, the results clearly showed that the HVED pretreatment of orange peels is efficient to enhance the accessibility of cellulosic biomass to enzymes. HVED (222u202fkJ/kg) prior to enzymatic hydrolysis (12 FBGU/g), was the most effective combination of these two processes to get an intensive extraction of biomolecules from orange peels.

Effects of ultrasound treatment and concentration of ethanol on selectivity of phenolic extraction from apple pomace

The extraction of polyphenols from apple pomace was studied using ultrasound, ethanol/water mixtures and moderate temperatures, 20–37xa0°C. The extraction kinetics and extraction yields of catechin and total phenolic content (TPC) were evaluated at different times of ultrasound treatment (tᵤ) and concentrations of ethanol (Cₑ). The highest extraction efficiency of TPC was observed at tᵤxa0=xa030xa0min, Cₑxa0=xa050% and total extraction time of tₑxa0=xa060xa0min. The high selectivity of catechin extraction was demonstrated by analysing the relative content of catechin (Rxa0=xa0Cc/TPC) in dependence of applied extraction protocol. The initial portions of extracts at small levels of TPC (≤50xa0mg per 100 DM) were richer in catechin content (Rxa0≈xa015%–31%), whereas the last portions of extracts with high level of TPS were more exhausted in catechin (Rxa0≈xa02%).

Comparison of conventional and ultrasound-assisted aqueous extraction of soluble matter and phenolic compounds from apple flesh

The extraction of soluble matter (°Brix), catechin and total phenolic compounds (TPC) from apple flesh was studied. A conventional aqueous extraction (CE) was done at different temperatures (50, 60, and 75xa0°C). A pulsed ultrasound-assisted extraction (UAE) was done at fixed temperature, Tu2009=u200950xa0°C, and different specific energy input and total duration. The main attention was focused on correlations between oBrix, concentration of catechin, C, TPC, and selectivity of phenolics extraction. For UAE, the significant acceleration in extraction of catechin was observed for the short duration protocol as compared with long duration one. The maximum (saturation) levels for concentrations of catechin, Cm, and total phenolic compounds, TPCm, were compared. In correlation between Cm and TPCm, the two distinctive branches were observed for CE protocols and UAE protocols. Moreover, the relative contents of catechin in TPC were noticeably higher for UAE protocols as compared with CE protocols.