Conventional Solid-liquid Extraction Research Articles

Green and sustainable techniques to increase the extraction of phenolic compounds from turnip greens by‐products

AbstractThe work was aimed to optimize extraction and recovery of phenolics from turnip greens by‐products using eco‐sustainable techniques based on the use of microwaves, ultrasound, or enzymes and of water as solvent. The optimization of ultrasound‐ and microwave‐assisted extractions was performed using a 4‐factors/3‐levels and a 3‐factors/3‐levels Box–Behnken Design (BBD), respectively and the results of the corresponding trials were fitted to a second order polynomial model. The enzymatic extractions were performed using three different commercial enzymatic preparations, optionally combined with an ultrasound treatment carried out according to the central values of the BBD design. The best results obtained from each green technique were compared with those of the conventional solid–liquid extraction performed with a 70% ethanol aqueous solution. Regarding ultrasounds, the conditions able to maximize the total phenolic concentrations of the extracts (solid–water ratio, 50 g/L; T, 45°C; t, 40 min; power, 24 W) increased the extraction efficiency by about 75% and reduced the extraction times from 2 h to 10 min with respect to the conventional extraction. Concerning microwaves, the optimized conditions (solid‐water ratio, 75 g/L; t, 3 min; power, 160 W) allowed the increase of the extraction efficiency by about 48% and the decrease of the extraction times to just a few minutes. For both techniques, the factor that mainly affected extraction yield and antioxidant activity were “solids‐to‐solvent ratio” and “power,” respectively. According to the results of the enzymatic treatments, the best extraction was that performed with the commercial mix of pectinlyase, polygalacturonase, pectinesterase, and arabinase, which had the same extraction efficiency of microwaves but required longer times (90 min). Furthermore, the combination with ultrasounds did not improve its performances. Extraction technique also affected the phenolic profiles in terms of number and concentration of compounds identified. In conclusion, ultrasounds and microwaves are the best treatments to maximize extraction yield (the first) and minimize extraction time (the second).Practical applicationsThis study presents an approach to the sustainable recovery of phenolics contained in vegetable by‐products that can be adapted to a variety of food waste. It also supplies an overview of the extraction technique efficiency. The industrial adoption of our findings can lead to the following advantages: reduction food waste and/or remove from it compounds that can alter the ecosystem balance; reduction of disposal cost; production of precious ingredients for functional foods/natural cosmetics/natural supplements; obtainment of a new source of income by creating a further activity that can run in parallel with the main production of the company and can serve to diversify investments; improvement of the green image of the company, especially if the energy necessary to the energy needed to power the new process is obtained from renewable sources.

Sustainable Valorization of Industrial Cherry Pomace: A Novel Cascade Approach Using Pulsed Electric Fields and Ultrasound Assisted-Extraction.

In this study, a two-stage cascade extraction process utilizing pulsed electric fields (PEF) (3 kV/cm, 10 kJ/kg) for initial extraction, followed by ultrasound (US) (200 W, 20 min)-assisted extraction (UAE) in a 50% (v/v) ethanol-water mixture (T = 50 °C, t = 60 min), was designed for the efficient release of valuable intracellular compounds from industrial cherry pomace. The extracted compounds were evaluated for total phenolic content (TPC), flavonoid content (FC), total anthocyanin content (TAC), and antioxidant activity (FRAP), and were compared with conventional solid-liquid extraction (SLE). Results showed that the highest release of bioactive compounds occurred in the first stage, which was attributed to the impact of PEF pre-treatment, resulting in significant increases in TPC (79%), FC (79%), TAC (83%), and FRAP values (80%) of the total content observed in the post-cascade PEF-UAE process. The integration of UAE into the cascade process further augmented the extraction efficiency, yielding 21%, 49%, 56%, and 26% increases for TPC, FC, TAC, and FRAP, respectively, as compared to extracts obtained through a second-stage conventional SLE. HPLC analysis identified neochlorogenic acid, 4-p-coumaroylquinic, and cyanidin-3-O-rutinoside as the predominant phenolic compounds in both untreated and cascade-treated cherry pomace extracts, and no degradation of the specific compounds occurred upon PEF and US application. SEM analysis revealed microstructural changes in cherry pomace induced by PEF and UAE treatments, enhancing the porosity and facilitating the extraction process. The study suggests the efficiency of the proposed cascade PEF-UAE extraction approach for phenolic compounds from industrial cherry pomace with potential applications to other plant-based biomasses.

An integrated method for rapid extraction of fluorescent whitening agents from selected cosmetics by in situ formation of deep eutectic solvent

A novel extraction methodology was developed based on deep eutectic solvent (DES) in situ formation. The solvent was synthesized from a binary mixture of L-cysteine, functioning as a hydrogen bond acceptor, and 2-methylphenol, serving as a hydrogen bond donor. The DES’s inherent molecular structures and extensive hydrogen bonding networks were characterized using the Fourier-transform infrared spectroscopy (FT-IR), while its hydrophobic nature was assessed by determining molecular polarity. Its extraction efficiency was demonstrated through the extraction of fluorescent whitening agents (FWAs) in cosmetic products, acting as a model analytical application. This was accomplished using vortex-assisted emulsification solid–liquid extraction (SLE) method, followed by high-performance liquid chromatography-fluorescence detection. Response surface methodology was employed to optimize extraction conditions in a multivariate experimental design. This approach streamlined the multi-operation extraction process via ingeniously integrating extraction and clean-up into a single step, resulting in significant reductions in extraction time required and high sample throughputs of approximately 40 samples per hour. The methodology was validated and exhibited excellent linearity in concentration ranges of 0.01–24 mg/L for five FWAs and 0.01–40 mg/L for other three FWAs, with correlation coefficients (r) ranging from 0.9985 to 1.000. The limits of detection and quantification were in the range of 0.03–0.26 mg kg−1 and 0.10–0.87 mg kg−1, respectively. The reliability and practicality of the proposed method were affirmed by quantifying eight FWAs in ninety-four commercially available facial masks and whitening creams, yielding recoveries values between 90.0 % and 106.0 % with relative standard deviations (RSDs) of 1.0–4.3 %. Inorganic ions and organic compounds present in the samples had minimal impact on FWAs detection following sample pre-treatment. This procedure showcased exceptional extraction capabilities towards a diverse array of FWAs with the aid of multiple interactions, suggesting significant potential for increasing sample throughput while reducing organic solvent and material consumptions compared with conventional SLE methods. The low-toxicity DES is an excellent alternative to traditional extractants typically applied to SLE techniques.

TEMPERATURE-DEPENDENT KINETICS OF ANTHOCYANINS EXTRACTION FROM RED ROSE PETALS

The red rose is one of the perspective natural resources of anthocyanins, however kinetic study for anthocyanins extraction of red rose petals is not yet elucidated. Red rose petals were dried at 303 K and ground (particle size ~ 5 mm). The petals were extracted by aqueous acid solutions using conventional solid-liquid extraction. The efficiency of 0.1 M aqueous solutions of acids as extractants towards red rose anthocyanins was studied and it can be arranged in the following row: citric acid < acetic acid < hydrochloric acid. Kinetic investigations focusing on the temperature effect on solid-liquid extraction of anthocyanins from petals of red rose were performed at three temperatures (293, 313, and 333 K). Kinetic curves were obtained using an aqueous solution of hydrochloric acid. It was found that the rate of extraction of anthocyanins was very fast at the beginning, but it began to slow down after 60 minutes for all temperatures. The experimental kinetic curves of the extraction of anthocyanins at different temperatures were obtained and analyzed using common empirical kinetic models (the first-order, second-order kinetic models, the Peleg model, and the power-law model). The second-order kinetic model provided the best agreement with the experimental results in terms of statistical parameters (coefficient of determination (R2) and average relative error (ARE)) than other studied models. As temperature increases, the second-order rate constant values and the initial extraction rate values also increased. The second-order rate constants were used to evaluate the activation energy of extraction. The calculated activation energy of the anthocyanin extraction is 39.3 kJ/mol, which is an indication of an endothermic process. Obtained data can be used to predict the extraction of anthocyanins from red rose petals.

Carob Pulp Flour Extract Obtained by a Microwave-Assisted Extraction Technique: A Prospective Antioxidant and Antimicrobial Agent

In this study, carob pulp flour (CF) extract was characterized as a high-value antioxidant and antimicrobial agent. CF extracts were obtained using microwave-assisted extraction (MAE) and optimization of the MAE process was accomplished using response surface methodology. The studied processing parameters of MAE were the liquid/solid (L/S) ratio (10–30 mL/g), extraction time (15–35 min), and ethanol concentration (40–80% w/w). The efficiency of the extraction of valuable compounds from CF was evaluated by the determining extraction yield (Y), total phenolic(TP), total flavonoid (TF) content, and antioxidant activity (DPPH, FRAP, and ABTS). The optimized MAE parameters for maximizing the yields of target compounds and antioxidant activity were the L/S ratio 30 mL/g, extraction time 35 min, and ethanol concentration 40%. The experimentally obtained values for TP, TF, DPPH, FRAP, and ABTS were 1609.92 GAE/100 g, 271.92 CE/100 g, 99.02 µMTE/g, 50.45 µM Fe2+/g, and 110.55 µMTE/g, respectively. The optimized CF extract was compared with the CF extracts obtained by conventional solid–liquid extraction (S/L) and ultrasound-assisted extraction (UAE) and was found to be more beneficial due to a 30% higher yield of TP and TF and 30–80% higher antioxidant activity. The phenolic profiles of the three extracts were quite similar. The microdilution method confirmed the antibacterial activity of MAE and S/L extracts while the antifungal effect was not observed.

Ultrasound-Assisted Extraction of Applewood Polyphenols at Lab and Pilot Scales.

This study focused on the extraction of polyphenols from applewood using ultrasonic-assisted extraction (UAE). First, the influence of solvent composition and mass-volume (m:v) ratio on the extraction yield was studied at a lab scale (200 mL). Overall, a ratio of 1:33 (m:v) resulted in a higher yield of polyphenols. Furthermore, both a higher yield of polyphenols and higher antioxidant capacity were detected in the extracts produced in the presence of a 30 v/v % ethanol mixture compared to pure water; a further increase in ethanol did not improve the extraction yield. Second, under the optimal conditions (30 v/v % ethanol-water; 1:33 and 1:20 (m:v)), the UAE technique was applied at a pilot scale (100 L). At 1:33 (m:v), the polyphenol yield was lower at the pilot scale compared to the lab scale; by contrast, at 1:20 (m:v), production at the pilot scale resulted in a higher yield compared to the lab scale. To identify and quantify individual polyphenols, HPLC-PDA analyses were performed. Phloridzin appears to be the major identified compound. Finally, the UAE process was compared to a conventional solid-liquid extraction technique, showing that a significantly higher yield could be obtained with UAE.

Effect of Microwave and Ultrasound-Assisted Extraction on the Phytochemical and In Vitro Biological Properties of Willow (Salix alba) Bark Aqueous and Ethanolic Extracts.

White willow (Salix alba) is a medicinal plant used in folk medicine. In this study, aqueous and ethanolic willow bark extracts were obtained via ultrasonic-assisted extraction (UAE) and microwave-assisted extraction (MAE), and analyzed regarding their phytochemical (total phenolics, phenolic acids, flavonoids, and tannins) content and in vitro biological properties (antibacterial and antifungal activity, acetylcholinesterase AChE inhibitory activity and anti-inflammatory effects). The highest phenolic, tannin, and flavonoid contents were found for willow bark extracts obtained via microwave-assisted extraction using ethanol as a solvent (SA-ME). The polyphenol load of all MAE and UAE extracts was higher when conventional solid-liquid extraction was applied (ρ < 0.05). The antioxidant capacities were stronger for microwave-assisted ethanolic extracts, with the lowest IC50 values of 12 μg/mL for DPPH• and a value of 16 μg/mL for ABTS•+, whereas the conventional extraction had the highest IC50 values (22 μg/mL and 28 μg/mL, respectively). Willow bark extract showed antibacterial activity against Gram-positive bacteria S. aureus and P. aeruginosa. AChE inhibitory activity was dependent on the extraction method and solvent used, and the highest inhibition among samples was observed for SA-ME. Taken altogether, our findings suggest that willow (Salix alba) bark extract obtained via ethanolic microwave-assisted extraction is a phytochemical-rich resource with in vitro, anti-inflammatory, and AchE inhibitory properties and, therefore, potential multiple medicinal end-uses.

Ultrasound-assisted polyphenol extraction of acerola and jambolan pomaces: comparison of extraction protocols, kinetic modeling, and life cycle assessment

In this study, tropical acerola and jambolan pomaces were submitted to four water-based polyphenol extraction methods: conventional solid-liquid extraction CSLE; heated conventional solid-liquid extraction HCSLE; static ultrasound-assisted extraction SUAE; and ultrasound-assisted extraction and mechanical stirring UAES. Our objective was to evaluate and compare the extraction protocols regarding their performance, extraction kinetics, mathematical modelling, and environmental viability using the life cycle assessment (LCA) tool. The highest total polyphenol content was obtained by UAES after 90 min (1,606.8 mg GAE/100g for acerola and 1,580.7 mg GAE/100g for jambolan). These results are significantly higher (p ≤ 0.05) compared to CSLE (1,296.4 mg GAE/100g for acerola, 644.1 mg GAE/100g for jambolan). The Power Law model showed the best experimental fit compared to Peleg's and second-order models. Regarding the environmental viability, the LCA tool revealed that UAES had the lowest environmental impact among all extraction protocols, mainly due to its lower energy consumption. Overall, the combination of mechanical stirring and ultrasound improved water-based polyphenol extraction rates with reduced energy consumption. This study shows UAES as an environmentally friendly strategy to achieve efficient extraction of naturally occurring polyphenols from tropical fruit pomaces.

Application of pressurized liquid extraction to grape by-products as a circular economy model to provide phenolic compounds enriched ingredient

The aim of this study was to valorise wine-making by-products optimizing the recovery of phenolic compounds from Cannonau grape pomaces using Pressurized Liquid Extraction (PLE). To achieve these goals, PLE experiments were performed by a Response Surface Methodology (RSM) based on a Central Composite Design 23 model to address the polar compound extraction. The selected independent variables were: temperature, composition of extractant solvent (% ethanol) and extraction time. The response variables were extraction yield and recovery of phenolic compounds. Phytochemical profile of PLE extracts was analysed by high-performance liquid chromatography coupled to a time-of-flight mass analyser (HPLC-ESI-TOF-MS) in order to address the individual phenolic extraction effectiveness. Hence, the optimum values to maximize phenolics extraction were 130 °C, 55% ethanol and 22 min. Extraction results obtained by using PLE system was compared with that obtained with conventional solid-liquid extraction. The proposed experimental model has proven to be a valuable alternative method to optimize extraction of bioactive compounds from wine-making by-products.

Process Optimization of Microwave-Assisted Extraction of Chlorophyll, Carotenoid and Phenolic Compounds from Chlorella vulgaris and Comparison with Conventional and Supercritical Fluid Extraction

The production of bioactive products from microalgae biomass with efficient and environmentally friendly technologies is a field of great research interest. The present work focuses on the recovery of high-added value bioactive components from Chlorella vulgaris through microwave-assisted extraction (MAE) with aq. ethanol 90% v/v. The effect of extraction temperature (40–60 °C), duration (5–25 min), solvent-to-biomass ratio (20–90 mLsolv/gbiom), and microwave power (300–800 watts) was investigated regarding the extraction yield, extract’s chlorophyll, carotenoid and phenolic content, and antioxidant activity. MAE optimization at 60 °C, 300 watts, 14 min, and 22 mLsolv/gbiom led to 11.14% w/w yield, 63.36 mg/gextr total chlorophylls, 7.06 mg/gextr selected carotenoids of astaxanthin, lutein and β-carotene, 24.88 mg/gextr total carotenoids, 9.34 mgGA/gextr total phenolics, and 40.49 mgextr/mgDPPH IC50 (antioxidant activity indicator). Moreover, the conventional solid-liquid extraction (SLE) with aq. ethanol 90% v/v, the supercritical fluid extraction (SFE) with CO2, as well as SFE with cosolvent addition (10% w/w ethanol), were also performed for comparison purposes. The results revealed that SLE presented the highest yield. However, the non-conventional methods of MAE and SFE led to extracts of competitive or even better quality under significantly shorter extraction duration.

Advanced extraction of caffeine and polyphenols from coffee pulp: Comparison of conventional and ultrasound-assisted methods

Two extraction methods of caffeine and total polyphenols from coffee pulp waste were evaluated using water as solvent: conventional solid-liquid extraction (CSLE) and ultrasound-assisted extraction (USAE). A central rotary experimental design was applied in each case, after evaluating the effect of the substrate:solvent ratio. The highest concentration of caffeine in the extractant using CSLE was found to be 49.9 ± 1.3 mg/L (equivalent to 3.7 ± 0.1 g/kg pulp, dry basis (d.b.)), after 5.5 min at 96 °C, and at a substrate:solvent ratio of 1:10 w/v. In parallel, the concentration of total polyphenols reached 128.3 ± 4.3 mg gallic acid equivalent (GAE)/L (9.7 ± 0.3 g/kg) at 75 °C (equal time and ratio). USAE was found to be also affected by power, leading to 206.6 ± 0.1 mg caffeine/L and 164.9 ± 5.2 mg GAE/L (15.6 ± 0.3 g/kg and 12.4 ± 0.2 g/kg, respectively) (396 W, 5.5 min, 75–90 °C). These results indicate extraction yields as high as 85%, at a markedly lower energy requirement using USAE. Consequently, USAE using water as a solvent might be a promising and innovative alternative to improve the extraction performance of highly demanded biocompounds from coffee pulp waste, with the consequent environmental and social benefits within a markedly relevant agro-industrial sector.

High Efficiency and New Potential of RSLDE: A Green Technique for the Extraction of Bioactive Molecules from Not Completely Exhausted Plant Biomass and Organic Industrial Processing Waste

A product is characterized by low environmental impact if, during the whole process (from extraction of raw materials from solid natural matter to disposal), its negative contribution to environment modification is significantly reduced or eliminated. According to circular economy, it is important to take into consideration other aspects, such as the possibility to improve the efficiency of extraction process by modifying the principle on which it is based and allowing the recovery of not completely exhausted waste, obtaining other active ingredients, and favoring the recycling of normally eliminated materials. The purpose of this work was to propose more efficient and greener alternatives to conventional solid–liquid extraction processes. Major features are the rapidity of the process, extraction at room temperature and high yields. Rapid Solid–Liquid Dynamic Extraction (RSLDE) represents an innovative solid–liquid extraction technology that allows the solid matrices containing extractable substances in an organic or inorganic solvent and their mixtures to be exhausted in shorter time than current techniques. The principle at the basis of this novel process consists of the generation of a negative pressure gradient between the inside and the outside of the solid matrix, which induces the extraction of compounds not chemically linked to the solid matter, being insoluble in the extractant liquid. Therefore, this work focuses on how RSLDE can potentially bring several improvements in the field of solid–liquid extraction, especially for industrial applications.

Enhancing the Production of the Phenolic Extracts of Asparagus Using an Advanced Green Process.

Asparagus officinalis L. is a common vegetable widely consumed due to its high consumer acceptance. In addition to its flavor, green asparagus contains a high amount of bioactive compounds with health-promoting effects. In this sense, the growing concern of the public health system to promote a diet with a higher consumption of vegetables makes research on phytochemicals from this food of interest. In order to study the content of bioactive compounds from plant matrices, the combination of advanced extraction and analytical techniques within the context of green chemistry is an indispensable working model in today’s research. In the present experimental work, the composition of the phytochemicals of green asparagus from the Protected Geographical Indication (PGI) located in Huétor Tájar, Granada (Spain), was evaluated by environmentally friendly extraction techniques. In order to carry out this work, the recovery of bioactive compounds was evaluated by pressurized liquid extraction (PLE) using GRAS (Generally Recognized As Safe) solvents (mixtures of water and ethanol). The extraction was optimized using a Response Surface Methodology (RSM) based on a 24 factorial Central Composite Design (CCD). The experimental model was followed by high-performance liquid chromatography coupled to electrospray ionization time-of-flight mass spectrometry (HPLC–ESI-TOF-MS) analytical methodology for a comprehensive characterization. The optimized methodology was compared with conventional solid–liquid extraction protocols using ethanol and water. The results highlighted the potential of advanced PLE techniques compared to conventional systems for the recovery of green asparagus phytochemicals. Moreover, the analytical characterization allowed the identification and quantitation of major phenolic compounds belonging to phenolic acids and flavonoids families. Therefore, an easy, fast, and novel methodology to optimize the extraction of bioactive compounds from green asparagus has been optimized, using Green and GRAS methodology, which enables a better understanding of the bioactive composition of this widely consumed food.

Valorization of distillery stillage by polyphenol recovery using microwave-assisted, ultrasound-assisted and conventional extractions

An increasing understanding of the negative environmental effects of waste discharges has made valorization of distillery by-products to recover added-value compounds a sound option for distillery stillage management. In this study, the recovery of bioactive compounds, i.e. polyphenols, from distillery stillage was performed by microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and conventional solid-liquid extraction (CSLE) to investigate the effects of extraction time, the concentration of ethyl acetate (EA) in a solvent mixture with ethanol and water, and solid-to-solvent ratio on the recovery yield and antioxidant activity of the extracts. The highest yields of total polyphenol content (TPC) (3.73 mg gallic acid equivalent/g) and phenolic acid content (2.51 μg/g) were obtained with 8-min MAE with 70% EA. MAE provided 1.2- and 1.4-times higher yield of phenolic acids and 1.2- and 1.6-times higher antioxidant activity than UAE and CSLE, respectively. Due to the approximately 3-times higher rate of extraction, the ratio between energy consumption and extraction yield was better in MAE than in UAE. Principal component analysis (PCA) showed that the antioxidant activity of the extracts was positively correlated with TPC and phenolic acid content. Six phenolic acids that were identified were present mainly in their free forms (up to 95% of the total), with a predominance of ferulic (up to 0.80 μg/g) and p-coumaric (up to 0.72 μg/g) acids.

A Systematic Review on Waste as Sustainable Feedstock for Bioactive Molecules—Extraction as Isolation Technology

In today’s linear economy, waste streams, environmental pollution, and social–economic differences are increasing with population growth. The need to develop towards a circular economy is obvious, especially since waste streams are composed of valuable compounds. Waste is a heterogeneous and complex matrix, the selective isolation of, for example, polyphenolic compounds, is challenging due to its energy efficiency and at least partially its selectivity. Extraction is handled as an emerging technology in biorefinery approaches. Conventional solid liquid extraction with organic solvents is hazardous and environmentally unfriendly. New extraction methods and green solvents open a wider scope of applications. This research focuses on the question of whether these methods and solvents are suitable to replace their organic counterparts and on the definition of parameters to optimize the processes. This review deals with the process development of agro-food industrial waste streams for biorefineries. It gives a short overview of the classification of waste streams and focuses on the extraction methods and important process parameters for the isolation of secondary metabolites.

Polyphenols extraction kinetics from Ascophyllum nodosum seaweed employing water and saltwater: Effect of ultrasound sonication

Saltwater (S), with the same ionic strength of seawater, was employed as solvent to extract polyphenols from seaweeds. Aqueous extracts were chemically characterized by means of total polyphenols (TPC), carbohydrates (CHOS) and uronic acids (UA) content and antioxidant capacities (DPPH, ABTS and FRAP). S-extracts showed lower TPC than those obtained with distilled water (D) using two different extraction methods, conventional solid-liquid extraction (SLE) and ultrasound-assisted extraction (UAE). The antioxidant capacities of both non-sonicated extracts did not show significant (p < 0.05) differences. SLE kinetics employing both solvents (D and S) were successfully modelled by Peleg's model, and equilibria were achieved after 15 min. Long-time UAE (15 min) increased phytochemical content in both D- and S-extracts with respect to SLE. Extracts showed three main (A, B, and C) regions from RP-HPLC profiles with different peak areas and shapes. Normalized regions areas from RP-HPLC were related to antioxidant activities by linear regressions and showed that B-region was the main responsible of phytochemical features of the extracts. SLE with saltwater promoted the leaching of other compounds (mainly proteins) that formed intermolecular complexes. These interactions were notoriously diminished with UAE. At these conditions, saltwater can be employed as eco-friendly solvent according to the green chemistry principles.

Potential Antioxidant and Antiviral Activities of Hydroethanolic Extracts of Selected Lamiaceae Species.

Medicinal and aromatic plants (MAPs) are potential sources of natural bioactive phytochemical compounds of an incredible worth for the food industry, such as polyphenols. Lamiaceae medicinal and aromatic plants from Granada’s high plateau, concretely Origanum bastetanum, Thymus zygis gracilis, Thymus longiflorus, Thymus membranaceus and Ziziphora hispanica, were evaluated under different conventional solid–liquid extraction conditions to obtain extracts enriched in bioactive compounds. Phenolic profile was detected by HPLC-QTOF-MS, identifying a high abundance of bioactive constituents. Furthermore, antioxidant and antiviral activities of the mentioned plants were studied as biological properties of interest for the improvement of food shelf-life. Thus, Origanum bastetanum showed the highest antioxidant potential for all assays. Antiviral activity was also tested against some important foodborne viruses, feline calicivirus (FCV), murine norovirus (MNV) and hepatitis A virus (HAV), with the highest activity obtained for Ziziphora hispanica, Thymus longiflorus and Origanum bastetanum. This research proposes the studied plants as rich sources of bioactive compounds with potential use as preservatives in the food industry.

A green approach to phenolic compounds recovery from olive mill and winery wastes

The aim of this study was to evaluate the recovery of phenolic compounds from olive mill and winery wastes by conventional solid-liquid extraction (SLE) using water as the extraction solvent. The studied variables were extraction time (5–15 min), temperature (25–90 °C), solid-to-liquid ratio (1:10–1:100 (kg/L)), pH (3−10) and application of multiple extractions (1–3). The extraction efficiency was evaluated in terms of total phenolic content (TPC), determined by high performance liquid chromatography (HPLC-UV), but also from the recovery of some representative phenolic compounds. The optimized conditions were one extraction step, 10 min, 25 °C, 1:30 (kg/L), pH 5 for olive pomace, and one extraction step, 10 min, 70 °C, 1:100 (kg/L), pH 5 for winery residues. The extraction method is simple and suitable for scaling-up in industry, and the aqueous extracts are fully compatible with further purification schemes based on the use of membranes or resins. The optimized technique was applied to a set of different representative residues from olive mill and winery industries, to assess their suitability as sources for phenolic compounds recovery. The phenolic content in the extracts was evaluated by chromatographic analysis and by the Folin–Ciocalteu assay (FC). Furthermore, the antioxidant capacity was determined by 2,2-azinobis-3-etilbenzotiazolina-6-sulfonat (ABTS), 2,-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. Because of their high contents in phenolic compounds and great antioxidant capacity, olive pomace and lees filters were identified as especially suited sources for phenolic compounds recovery.

Polyphenols in fig: a review on their characterisation, biochemistry during ripening, antioxidant activity and health benefits

SummaryFig fruit (consumed either fresh or dried) is a rich source of polyphenols distributed throughout its peel and pulp. However, the peel part is superior in diversity of these compounds in comparison to the pulp. Fig polyphenols have been extracted both by conventional solid–liquid extraction and novel assisted methods (mainly ultrasound‐assisted and microwave‐assisted procedures). These can be characterised primarily into flavonoids (anthocyanins, flavan‐3‐ols and various flavonol glycosides) and phenolic acids. Figs contain good levels of anthocyanins (such as cyanidin‐3‐O‐glucoside, cyanidin‐3,5‐diglucoside and cyanidin‐3‐O‐rutinoside) which impart different colouring hues to these fruits during the ripening process. Moreover, fig polyphenols have associated antioxidant activities and impart many health benefits such as antihyperglycaemic, hepatoprotective and antispasmodic activities. This review provides a thorough information on the fig polyphenols, stressing on their extraction, characterisation as well as quantification, the biochemical changes during the ripening process, associated antioxidant activity and health benefits.

A novel cascade approach to extract bioactive compounds from officinal herbs

This research aims to compare a novel cascade extraction method with a conventional solid–liquid extraction method, both assisted by ultrasounds. The cascade extraction method consists of a sequential series of extractions performed with the same hydroalcoholic solvent, which is reused from one herb to the other. In practice, a hydroalcoholic solution is firstly used to extract one botanical herb. The resulting extract is then reused for the extraction of a second herb. The process is repeated as many times as the number of herbs composing the final formulation. The main advantage of this approach is firstly the lower need of solvents compared with the individual extraction procedures, where a fresh solvent is needed on each extraction step. Furthermore, extracts of the two methods (solid liquid vs cascade extraction) were characterized with several antioxidant assays (DPPH, ORAC, and FRAP) and total phenolic content (TPC). The results show that the solid–liquid extraction method achieves similar yields to total phenols and similar TAC in comparison to the extracts obtained by the cascade extraction method. Also, the HPLC analysis of the extracts showed that both methods lead to similar chromatographic profiles either when analyzed by an electrochemical detector (CoulArray) or by a spectrometric diode array detector (DAD). However, our findings support the idea that the cascade extraction method obtains extracts richer of minor peaks, showing a more complex bioactive profile. Such results could be explained considering that the solvent used during the series of cascade extractions was enriched not only by antioxidants but also by plant surfactants, like saponins, which increase the solvent solubility. Overall, this research shows that the cascade extraction method can not only provide officinal herb extracts with similar phenolic yield and antioxidant capacity than conventional solid–liquid extraction but also with a more complex bioactive profile compared to traditional solid–liquid extraction and with a minor consumption of solvents.