Pulsed electric fields- and ultrasound-assisted green extraction of valuable compounds from Origanum vulgare L. and Thymus serpyllum L.

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 4 h. The rate of phenolic compounds extraction decreased with time and was predicted rather satisfactorily (R² = 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 optimised PEF (3 kV cm⁻¹, 10 kJ kg⁻¹) and US (400 W, 20 min) treatment conditions, the extracts obtained from either PEF or US pretreated 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.     

Shelf-life evaluation of virgin olive oil extracted from olives subjected to nonthermal pretreatments for yield increase

Critical process parameters for the yield and quality of olive oils are the temperature and treatment duration of the malaxation process. A balance between oil yield and quality must be achieved. Novel technologies such as High Pressure (HP) and Pulsed Electric Fields (PEF) that cause alterations to cell permeability, may promote the olive oil extraction process during malaxation, resulting in higher oil yields.Three different varieties of Olive fruits (Tsounati, Amfissis and Manaki var.) were subjected to different HP (200 and 600 MPa, 25 °C for 1 and 5 min) and PEF (1.6–70.0 kJ/kg) process conditions before malaxation (30 min at 30 °C). The extraction yield was increased up to 18 and 16% for PEF and HP treated olive fruits, respectively. The shelf-life tests indicate that the oil quality from nonthermally pretreated olives is dependent on the technology and process conditions used. An increase of oil oxidative stability for PEF and HP treated olives was shown, compared to control samples.The results show that HP and PEF could be applied for the production of superior quality virgin olive oil with increased yield.     

Influence of ethanol/water ratio in ultrasound and high‐pressure/high‐temperature phenolic compound extraction from agri‐food waste

The valorisation and management of agri‐food waste are currently hot investigation topics which probe the recovery of valuable compounds, such as polyphenols. In this study, high‐pressure/high‐temperature extraction (HPTE) and ultrasound‐assisted extraction (UAE) have been used to study the recovery of phenolic compounds from grape marc and olive pomace in hydroalcoholic solutions. The main phenolic compounds in both extracts were identified by HPLC‐DAD. Besides extraction yield (total polyphenol and flavonoid content) and the antiradical power, polyphenol degradation under HPTE and UAE has also been studied. HPTE with ethanol 75% gave higher phenolic extraction yields: 73.8 ± 1.4 mg of gallic acid equivalents per gram of dried matter and 60.0 mg of caffeic acid equivalents per gram of dried matter for grape marc and olive pomace, respectively. In this study, the efficient combination of ethanol/water mixture with HPTE or UAE has been used to enhance the recovery of phenolic compounds from grape marc and olive pomace. HPLC‐DAD showed that UAE prevents phenolic species degradation damage because of its milder operative conditions.     

Use of Supercritical Assisted Atomization to produce nanoparticles from olive pomace extract

Olive pomace is one of the most interesting wastes containing bioactive compounds; the extraction of polyphenols can represent an innovative solution for the reduction of the environmental hazard of this solid and the simultaneous recovery of high-added value compounds. In this study, Supercritical Assisted Atomization (SAA) was employed for the encapsulation in maltodextrin of phenolic compounds extracted from olive pomace. The effect of the ratio of maltodextrin content to total solid content of the extract and drying temperature on physical characteristics, total phenolic content and antioxidant properties of the powdered product were studied. The results confirmed the efficiency of the SAA process to encapsulate phenolic compounds from olive pomace extract. Particles with average diameter of 712 nm with high total polyphenol content (105.0 ± 0.1 mg_{Caffeic Acid Equivalent/}g_{Dry Powder}) and antiradical power (98.8 ± 3.0 mg_DPPH/mL_extract) were obtained. These particles rich in bioactive compounds can be used as functional component in formulations of new food, cosmetic or pharmaceutical products.Industrial relevanceOlive pomace is considered to be a low-cost and renewable source of high-added value compounds, such as polyphenols which can be valorized by several methodologies. In this work, we assessed the efficiency of Supercritical Assisted Atomization (SAA) in order to encapsulate phenolic compounds extracted from olive pomace. The particles obtained by SAA have spherical morphology with average diameter of 712 nm. The polyphenol-rich nanoparticles produced using this technique can be potentially used in the formulation of novel food or nutraceutical products.     

High‐pressure recovery of anthocyanins from grape skin pomace (Vitis vinifera cv. Teran) at moderate temperature

The objective was to evaluate the influences of the high hydrostatic pressure extraction parameters on the recovery of anthocyanins from the grape skin pomace extracts (Vitis vinifera cv. Teran) under moderate temperatures. Studied parameters were: solvents (methanol and ethanol); solvent concentrations (30, 50, and 70%); pressures (300, 400, and 500 MPa); times (3, 6.5, 10 min); and temperatures (22, 26, 30 °C). Predominant anthocyanins in all extracts were malvidins (malvidin‐3‐glucoside as the main compound) representing 55.77% of overall anthocyanin content. The type of solvent did not significantly influence anthocyanin extraction yield, while decreased solvent concentration (increased solvent‐to‐water ratio) significantly improved extraction of anthocyanins. Increase of pressure enhanced extraction yield of the anthocyanins but temperature showed stronger impact on the anthocyanins recovery. This investigation evidenced that the best conditions for HHPE of anthocyanins from grape pomace were extraction time 3.39 min, extraction temperature 29.48 °C, pressure 268.44 MPa and solvent concentration 70%.

Practical applications

Due to increased interest for the use of cheap winery byproducts as a source of expensive polyphenols for functional food production, skins from grape pomace became valuable raw material. Therefore, there is a need to evaluate the influence of HHPE innovative extraction technology on its nutritive value during processing. Optimizing parameters for polyphenolic recovery from grape pomace is directly related with nutritional value and economics of food engineering during industrial processing. Obtained results showed that the HHPE under lower temperatures is suitable for the extraction process of anthocyanins from grape skin pomace, but more research is needed to identify other food‐grade solvents with their corresponding concentrations that are useful for the extraction assisted with high hydrostatic pressure.     

Combined densification and pulsed electric field treatment for selective polyphenols recovery from fermented grape pomace

The aim of this study is to assess a new process for the valorization of fermented grape pomace using pulsed electric fields (PEF). The combination of densification and PEF treatment was applied on grape pomace of low relative humidity, without any addition of conductive liquid. The kinetics of extraction and the composition of polyphenols were evaluated throughout the subsequent hydro-alcoholic extraction at different temperatures.Optimal parameters of PEF treatment (field strength E = 1.2 kV·cm^− 1; energy input W = 18 kJ·kg^− 1; density ρ = 1.0 g·cm^− 3) increased the content of total polyphenols regardless of the temperature of extraction. The ratio of total anthocyanins to total flavan-3-ols at 20 °C was equal to 7.1 and 9.0 for control and PEF treated modalities, respectively. These results demonstrate the selective nature of PEF treatment in anthocyanin extraction, and thus reveal new possibilities to produce extracts with different biochemical compositions.Industrial relevanceThis study examines the feasibility of densification combined with PEF pre-treatment of relatively low humidity grape pomace for the enhancement of bioactive compounds extraction. The concentration of total phenolic compounds obtained after PEF treatment showed that the use of this technique is relevant for an industrial use, since solvent amount and extraction time can be reduced. Moreover, the selective nature of PEF opens the opportunity to produce extracts of different biochemical compositions. This process is an alternative to conventional pre-treatments of raw material (e.g. dehydration and grinding), which have impacts on product quality and are more energy consuming.     

Concentration of phenolic compounds from apple pomace extracts by nanofiltration at lab and pilot scale with a techno‐economic assessment

Apple pomace can be used as resource for the extraction of phenolic compounds with antioxidant properties. Pressing of apple in juice and pomace at lab scale in open air (aerobic) and under N₂ atmosphere (anaerobic) showed a recovery of phenolic compounds of 85% in juice and pomace after anaerobic pressing, compared to 43% after aerobic pressing, indicating loss of phenolic compounds by oxidation and the advantage of anaerobic over aerobic pressing. After a membrane screening and concentration test at lab scale, the commercial nanofiltration membrane NFX was selected to concentrate phenolic compounds in an ethanol : water extract of apple pomace. At pilot scale, the concencentration of 10 selected phenolic compounds and quinic acid increased from 59.5 mg/L in the ethanol : water extract to 1256.1 mg/L in the final retentate, that is, by a factor 21.1. The volume of the crude extract was reduced by a factor of 28.5 during the filtration, indicating some loss of phenolic compounds during pilot testing due to membrane fouling or oxidation of polyphenols. The pilot concentration test using a spiral‐wound membrane module showed good flux and concentration of phenolic compounds, indicating the technical feasibility of membrane technology for efficient concentration of polyphenols in an ethanol : water extraction solvent. Unfortunately, the extraction and concentration process was not economically feasible under the assumptions made.

Practical applications

The valorization of food waste for the production of high‐added value products is an increasingly hot topic. Phytochemicals are present in relatively low concentration in the fruit matrix, and concentration in the extraction solvent is necessary to develop an industrially relevant process. In this study, membrane filtration was selected for concentration due to its low energy consumption and mild processing conditions compared to other technologies. Membrane screening and testing at lab and pilot scale with techno‐economic assessment can be used by food and nutraceutical industries to evaluate membrane technology for concentration of phytochemicals extracted from agroindustrial by‐products.     

Pulsed electric fields (PEF), pressurized liquid extraction (PLE) and combined PEF + PLE process evaluation: Effects on Spirulina microstructure,biomolecules recovery and Triple TOF-LC-MS-MS polyphenol composition

This study aims at evaluating the impact of different processes-pulsed electric fields (PEF), pressurized liquid extraction (PLE) and a multistep process combining PEF + PLE on the yield of antioxidant compounds (protein, polyphenols, chlorophyll a, chlorophyll b, and carotenoids) from Spirulina. Firstly, the effects of PEF or PLE treatment on the extraction yield of Spirulina biomolecules were evaluated. To further increase the extraction yield, PEF + PLE was used, as an innovative extraction approach. The results showed that PEF + PLE greatly improved the extraction yield compared with the PEF or PLE treatments alone. Compared with Folch extraction (conventional control technique), PEF + PLE significantly (P < 0.05) shortened the extraction time (−165 min) and increased the protein, polyphenol, chlorophyll a and antioxidant capacity values of Spirulina extracts by 1328%, 979%, 11% and 47% respectively. Furthermore, Triple TOF-LC-MS-MS results showed that PEF + PLE increased both the type and content of phenolic compounds. The above results were attributed to PEF-induced damage on Spirulina helical structure, which was verified by fluorescence and scanning electron microscopy.     

Syrah grape skin valorisation using ultrasound-assisted extraction: Phenolic compounds recovery,antioxidant capacity and phenolic profile

The influence of ultrasound power (1000–3000 W/L), citric acid concentration (0–3%) and solid:liquid ratio (1:5–1:15) on the phenolic compounds recovery and antioxidant capacity of Syrah grape skin extracts were evaluated. Total phenolic compounds varied from 6485 to 11732 mg gallic acid/100 g and monomeric anthocyanin content from 453 to 685 mg malvidin-3-glucoside/100 g. The antioxidant capacity measured by ORAC and ABTS methods ranged from 230 to 516 μmol Trolox/g and from 442 to 939 μmol Trolox/g, respectively. The most suitable conditions chosen for extraction, within the studied ranges, were 3000 W/L of power, 2.5% citric acid and solid:liquid ratio of 1:15. The extraction yield was satisfactory, with a recovery of 59% of the quantified phenolic compounds, with only 3 min of processing. Ultrasound was considered a suitable method as compared to the conventional extraction, improving the extraction of phenolic acids and facilitating their release.     

Optimization and economic evaluation of pressurized liquid extraction of phenolic compounds from jabuticaba skins

The optimization of the extraction of anthocyanins and other phenolic compounds from jabuticaba skins, a promising Brazilian source of these compounds, was studied using pressurized liquid extraction (PLE). An optimization study was performed using ethanol as a solvent and with extraction pressure (5-10 MPa), temperature (313-393 K) and static extraction time (3-15 min) as independent variables. The optimum PLE conditions for all response variables were estimated; however, PLE conditions resulting in the highest recovery of anthocyanins (5 MPa, 553 K and 9 min of static extraction time) were chosen for comparison with a conventional low-pressure solvent extraction (LPSE). The attributes compared were yield, content of anthocyanins and phenolic compounds and economic feasibility. Similar extraction yields were obtained by LPSE and PLE under optimized conditions; however 2.15 and 1.66-fold more anthocyanins and total phenolic compounds, respectively, were extracted using PLE, while the cost of manufacturing (COM) obtained for the PLE extract was 40-fold lower.     

The effect of Pulsed Electric Field as a pre-treatment step in Ultrasound Assisted Extraction of phenolic compounds from fresh rosemary and thyme by-products

Emerging extraction techniques, including pulsed electric field (PEF) and ultrasound (US), are attracting considerable interest in the recovery of bioactives. Though, limited work has focused on PEF application as pre-treatment for US assisted extraction to enhance the release of phenolics from herbs. Hence, the present study investigated the use of an optimized PEF pre-treatment to enhance the recovery of phenolics from fresh rosemary and thyme by-products in a subsequent US assisted extraction step. Total phenolic content (TPC), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) were assessed as an index of extraction efficacy. Qualitative and quantitative analyses were performed through liquid chromatography-mass spectrometry analyses to evaluate the influence of the methods on individual phenolic compounds and the formation of potential derivatives. The results indicated that in a number of cases PEF pre-treatment enhanced (p < 0.05) the recovery of phenolic compounds and antioxidant capacity compared to US individually.     

Addition of enzymes complex during olive oil extraction improves oil recovery and bioactivity of Western Australian Frantoio olive oil

Olive oil consumption has increased as many studies revealed the health benefits of regular consumption of olive oil. There is a need to find effective oil extraction techniques capable of increasing oil recovery without compromising its quality. This study investigated the impact of adding enzymes complex Viscozymes during olive oil extraction on oil recovery, total phenolic compounds, antiradical activity and the standard quality parameters. It was found that at a concentration of 0.30 g mL^?1, Viscozymes could significantly improve the oil recovery from 49 to 69% (P < 0.001) when compared to the Control sample. The concentration of total phenolic compounds was also significantly improved from 110 to 266 mg kg^?1 oil (P < 0.01) and the antiradical activity increased from 31 to 48% inhibition of 2,2‐diphenyl‐1‐picrylhydrazil radical (P < 0.001). Addition of Viscozymes therefore represents an effective extraction technique that increases oil recovery without compromising the concentration of total phenolic compounds and antiradical activity.     

Effects of high pressure on biochemical properties and structure of myofibrillar protein from Tegillarca granosa

The effects of high-pressure (HP) treatment parameters (300 MPa for 5 min, 350 MPa for 3 or 5 min and 400 MPa for 1 min) on the biochemical properties and structure of myofibrillar protein (MP) from Tegillarca granosa were investigated. The results showed that HP significantly affected the biochemical properties of MP. Under the HP treatment at 400 MPa for 1 min, the MP extraction yield was reduced from 32.21 to 18.34 mg g⁻¹, and its surface hydrophobicity was increased from 89.29 to 104.69 µg. Ca²⁺-ATPase activity of MP decreased from 0.019 to 0.011 µmol (pi) mg⁻¹ (pro) min⁻¹, and both total and reactive sulfhydryl contents significantly declined. Furthermore, HP caused MP to undergo conformational changes. This study provides a reference data for the processing of T. granosa using HP treatment.     

Effects of high pressure extraction on the extraction yield,total phenolic content and antioxidant activity of longan fruit pericarp

High pressure extraction (HPE) was carried out to extract phenolic compounds from longan fruit pericarp. The influence of different solvents, solvent concentration (25?100%, v/v), solid to liquid ratio (1:25?1:100, w/v) were individually determined using these optimum extraction conditions. HPE was carried out at various pressures (200?500 MPa), durations (2.5?30 min) and temperatures (30?70 °C). The extraction yield, total phenolic contents and scavenging activities of superoxide anion radical and 1,1-dipheny l-2-picrylhydrazyl (DPPH) radical of HPE extract were examined and then compared with those of the conventional extraction (CE). The application of HPE obtained a higher extraction yield and required a less extraction time when compared to CE. Furthermore, the total phenolic contents and the antioxidant activities of HPE extract were higher than CE extract. This study indicated that this new technology can benefit the food and pharmaceutical industries.Industrial relevanceThis study focused on the evaluations of the extraction yield, total phenolic content and antioxidant activity of longan fruit pericarp by high pressure treatment. The high pressure extraction technology provided a better way of utilizing longan fruit pericarp as a readily accessible source of natural antioxidants in food and pharmaceutical industries.     

Effect of pulsed electric field processing on carotenoid extractability of carrot purée

The purpose of this research was to study the effect of electric field strength (0.1–1 kV cm^?1) and frequency (5–75 Hz) during pulsed electric field (PEF) processing on the extractability of carotenoids in carrots, which was examined using different vegetable oils. Increasing electric field strengths up to 1 kV cm^?1 at 5 Hz significantly (P < 0.05) increased the extraction of carotenoids from carrot pomace. Increasing frequency above 10 Hz at 1 kV cm^?1 did not improve the carotenoids extraction. The yield of carotenoids extracted was dependent on the vegetable oils. Sunflower and soya bean oils had the highest carotenoid extractability, and peanut oil was the lowest for carrot pomace treated at 0.6 kV cm^?1 and 5 Hz, but no significant difference was observed among vegetable oils for carrot pomace treated at 50 Hz. This study suggests that PEF can improve the carotenoids extractability of carrots depending on the electric field strength and frequency used.     

Optimization of betulin extraction process from Inonotus Obliquus with pulsed electric fields

In this work, the extraction of betulin from Inonotus Obliquus applying high intensity pulsed electric fields (PEF) was studied. To extract non-polar compound, 75% ethanol solution was used. The effect of PEF on betulin yield was discussed compared with conventional extracting method. A set of optimal parameters (PEF strength = 40 kV/cm, pulse number = 2, ethanol concentration = 75%, and solid-to-solvent ratio = 1:25) were tested and analyzed.

Industrial relevance

Results of this study show that pulsed electric fields can be used to extract non-polar compound from plant origin raw material, such as Chinese herbal medicine, with easy-to-use equipment, materials and shorter extracting time compared with conventional methods.     

Application of electrical treatments in alcoholic solvent for polyphenols extraction from grape seeds

The polyphenols extraction from grape seeds was studied. In order to increase the polyphenols yield and the extraction kinetics, three different pre-treatments were applied on grape seeds: pulsed electric fields (PEF) (8–20 kV/cm, 0–20 ms), high-voltage electrical discharges (HVED) (10 kA/40 kV, 1 ms) and grinding (180 W, 40 s). These electrical treatments can damage cell membranes (PEF/HVED) and cell walls (HVED) thus accelerating the compounds extraction but have different effects on the product fragmentation. The diffusion was then performed after pre-treatment with a mixture of water and ethanol. The PEF efficiency was improved when the treatment was performed at 50 °C in the presence of ethanol. PEF-assisted diffusion was then compared to HVED-assisted diffusion and to diffusion of ground grape seeds. These two pre-treatments increased both the extraction kinetics and the maximum polyphenols yield. For both cases, the final polyphenols content was 9 g GAE/100 g DM after 15 min of extraction with grinding and after 60 min with HVED. When PEF were applied in a suspension containing ethanol, the maximum polyphenols yield was also reached after 60 min. The subsequent solid–liquid separation was faster with PEF as compared to ground and HVED-treatments.     

Valorization of Apple Pomace by Extraction of Valuable Compounds

Apple pomace is a promising source of carbohydrates, proteins, amino acids, fatty acids, phenolic compounds, vitamins, and other compounds with a vast range of food applications. This review focuses on the valorization of apple pomace towards the recovery of the main compounds, namely pectin and polyphenols. Applications, advantages, and drawbacks of conventional extraction (acidic medium under high temperatures) compared with novel extraction technologies are presented. The comparison is based on an extensive literature review of research on extraction of valuable compounds from plant matrixes, particularly apple pomace. Novel extraction techniques involving enzymes, electric field, ultrasound, microwave heating, pressurized liquid, and super/subcritical fluid are also discussed. These techniques offer several advantages, including shorter extraction time, increased yield, reduction—or suppression—of solvents, and minimization of the environmental impact. This paper may help researchers and food industry professionals on the scaling‐up and optimization of eco‐friendly extractions of pectin and phenolic compounds.     

Static,Kinetic, and Isotherm Adsorption Performances of Macroporous Adsorbent Resins for Recovery and Enrichment of Bioactive Procyanidins from Cranberry Pomace

This study examined the ability of five Amberlite resins coupled with ultrasound‐assisted water extraction for the recovery and enrichment of bioactive procyanidins and total phenolics from cranberry pomace. Static adsorption showed that XAD‐7HP had the highest adsorption capacity for procyanidins (52.2 mg/g resin) and total phenolics (99.1 mg/g resin) whereas XAD‐761 had the lowest. Adsorption of procyanidins fitted better to pseudo‐second‐order kinetics than pseudo‐first‐order kinetics. Isotherm adsorption on XAD‐7HP suggested that Langmuir isotherm was a better model to describe the adsorption of procyanidins while Kemkin–Pyzhev equation was better for total phenolics based on higher coefficient of determinations (R²). Dynamic tests on XAD‐7HP suggested that the flow rate of 7 and 8 mL/min were the optimum conditions for adsorption and desorption of procyanidins, respectively. Measurements using HPLC revealed that adsorption increased the contents of procyanidins and total phenolics by 4.57‐ and 4.73‐folds, respectively, compared to the initial extracts. This research showed that Amberlite XAD‐7HP resin adsorption coupled with ultrasound‐assisted water extraction is an efficient method to separate and concentrate procyanidins from cranberry pomace.     

Carotenoid and flavanone content during refrigerated storage of orange juice processed by high-pressure, pulsed electric fields and low pasteurization

The impact of different processing technologies, including non-thermal technologies, on bioactive compounds of orange juice was investigated. Freshly squeezed orange juice was treated by high pressure (HP) (400 MPa/40 °C/1 min), pulsed electric fields (PEF) (35 kV cm⁻¹/750 μs) and low pasteurization (LPT) (70 °C/30 s). The stability of main carotenoids and flavanones was studied just after treatment and during 40 days of refrigerated storage at 4 °C. Just after treatment, HP juice showed a significant increase on total carotenoid and flavanone content extracted (45.19 and 15.46%, respectively) and on vitamin A value (30.89%) with regard untreated juice, whereas no significant changes were observed for PEF and LPT juices. For all treated orange juices, flavanone content decreased significantly (around 50%) during the first 20 days of storage at 4 °C while carotenoid content showed a moderate decrease (less than 11%) that took place during the last 20 days. In general, during refrigerated storage, carotenoids and flavanones remained higher in HP juice than in LPT and PEF juices. Hence, HP and PEF technologies were as effective o even more than LPT to preserve bioactive compounds in orange juice during refrigerated storage.