Pressurized liquids vs. high intensity focused ultrasounds for the extraction of proteins from a pomegranate seed waste

Pomegranate processing results in a waste with high protein content and potential industrial applicability. The reuse of these proteins requires their previous extraction and characterization. Nevertheless, extraction of proteins from vegetal tissues is a difficult task, and methodologies commonly applied for this purpose are non-sustainable and show low yields. Pressurized liquids extraction (PLE) is a sustainable technique scarcely applied for the extraction of proteins. PLE and high intensity focused ultrasounds (HIFU) have been compared in this work to recover proteins from a pomegranate seed waste. PLE extracted more proteins than HIFU, but it took longer and still co-extracted phenolic compounds. Extracted proteins were also characterized. Proteins separation by isoelectrofocusing electrophoresis revealed that the extraction technique, PLE or HIFU, significantly affected the solubility of proteins. Peptides released by simulated gastrointestinal digestion of extracted proteins also showed important differences when they were identified by UHPLC-MS/MS. Many identified peptides showed common features with antioxidant, antihypertensive, and hypocholesterolemic peptides. These activities were also confirmed by in vitro studies. PLE samples demonstrated, in general, higher bioactivity than HIFU. In addition to phenolic compounds, significantly co-extracted with proteins by PLE, other interesting compounds were also identified (e.g. azelaic acid).Industrial relevanceExtraction of proteins is usually carried out using non-sustainable methods that results in low yields and protein degradation. This work purposes the use of pressurized liquids extraction (PLE) for the recovery of proteins from a pomegranate seed waste, and compares these results with the obtained using high intensity focused ultrasounds (HIFU). PLE extracted more proteins but it required longer times than HIFU and co-extracted more phenolic compounds. The extraction procedure significantly affected proteins solubility and extracts composition. Proteins, peptides, and phenolic compounds contributed to the bioactivity of extracts. This work demonstrates that this waste is a sustainable and cheap source of proteins and bioactive molecules with high potential for the preparation of bioactive compounds, nutraceuticals, and cosmetics.     

High voltage electrical discharges followed by deep eutectic solvents extraction for the valorization of pomegranate seeds (Punica granatum L.)

This work proposes a sustainable methodology based on the use of high voltage electrical discharges (HVED) and deep eutectic solvents (DES) for the simultaneous extraction of proteins and polyphenols from pomegranate seeds. Pomegranate seeds were firstly pretreated with HVED and, next, submitted to a solid-liquid extraction using DES. HVED pretreatment was compared with ultrasounds observing a better performance of HVED that promoted the disintegration of 86% of cells at 160 kJ/kg energy input and, consequently, the release of 70% of proteins and 78% of polyphenols. Extraction/solubilization of proteins and polyphenols was carried out using 5 different DES and results were compared with the obtained using NaOH. DES improved the diffusivity of both proteins and polyphenols, although the highest rates were observed for proteins, while NaOH extracted higher amounts of both. Application of RP-HPLC-ESI-Q-TOF to the analysis of extracts enabled to identify 30 different phenolic compounds among extracts, most of them ellagitannins. Proteomics enabled to identity a total of 11 different proteins among pomegranate seed extracts that were mainly assigned to globulins and albumins, with nutrient reservoir activity.     

Protein valorization from ora-pro-nobis leaves by compressed fluids biorefinery extractions

Ora-pro-nobis (Pereskia aculeata) leaves were selected as raw material for biorefinery application based on compressed fluid extractions with green solvents. The fractionation followed the sequential processes: (1) Supercritical fluid extraction (SFE) with CO₂, (2) Gas expanded liquid extraction (GXL), using CO₂:Ethanol, and pressurized liquid extraction (PLE) with ethanol, and (3) Subcritical water extraction (SWE). In vitro analysis of total phenolic and total carotenoid contents and antioxidant activity (DPPH and ORAC) were assessed, stipulating PLE method as the second step of the sequential extractions. Total protein and carbohydrate contents were evaluated from SWE samples. Phenolics profile from PLE and SWE samples was assessed by LC-DAD-ESI-MS/MS, identifying 8 phenolic compounds, with quercetin, isorhamnetin and kaempferol as the main detected flavonoids. SWE at 150 and 185 °C provided the highest protein recovery, as the third step in a sequential process.     

Green solvents for the selective extraction of bioactive compounds from by-products of the coffee production chain

Approximately 15–20 million tonnes of by-products were generated globally in the coffee production chain during the 2020/21 season. The current uses for these by-products are inadequate or contribute to environmental degradation. This work reports the screening of hydrophilic and hydrophobic solvents, including deep eutectic solvents (DES), for their ability to extract the valuable metabolites caffeine and chlorogenic acid (markers in commercial extraction) from four coffee-related by-products. Water was the best solvent for recovering caffeine and chlorogenic acid from defective green coffee beans, while all hydrophilic DES surpassed water in the extraction of chlorogenic acid from coffee pulp. For the two remaining by-products, at least one DES was as good or better at extracting the caffeine or chlorogenic acid compared to water. The array of hydrophobic solvents tested here showed different selectivities, allowing the annotation of 12 compounds that have not been previously reported in coffee by-products. These results demonstrate the ability to obtain a new and controllable range of extracts from coffee by-products using green and functional solvents.     

Antioxidant capacities of phenolic compounds and tocopherols from Tunisian pomegranate (Punica granatum) fruits

This article aims to determine the phenolic, tocopherol contents, and antioxidant capacities from fruits (juices, peels, and seed oils) of 6 Tunisian pomegranate ecotypes. Total anthocyanins were determined by a differential pH method. Hydrolyzable tannins were determined with potassium iodate. The tocopherol (α-tocopherol, γ-tocopherol, and δ-tocopherol) contents were, respectively, 165.77, 107.38, and 27.29 mg/100 g from dry seed. Four phenolic compounds were identified and quantified in pomegranate peel and pulp using the high-performance liquid chromatography/ultraviolet method: 2 hydroxybenzoic acids (gallic and ellagic acids) and 2 hydroxycinnamic acids (caffeic and p-coumaric acids). Juice, peel, and seed oil antioxidants were confirmed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. The highest values were recorded in peels with 25.63 mmol trolox equivalent/100 g and 22.08 mmol TE/100 g for FRAP and ORAC assay, respectively. Results showed that the antioxidant potency of pomegranate extracts was correlated with their phenolic compound content. In particular, the highest correlation was reported in peels. High correlations were also found between peel hydroxybenzoic acids and FRAP ORAC antioxidant capacities. Identified tocopherols seem to contribute in major part to the antioxidant activity of seed oil. The results implied that bioactive compounds from the peel might be potential resources for the development of antioxidant function dietary food.     

A systematic approach for extraction of phenolic compounds using parsley (Petroselinum crispum) flakes as a model substrate

The impact of extraction methodology and polarity of extraction solvents on the assay of phenolic compounds was investigated using parsley (Petroselinum crispum) flakes as a model substrate. This systematic study was undertaken to address substantial variations in the extraction procedures, solvents and conditions as described in the recent literature. Five different extraction procedures [shaking, vortex mixing, sonication, stirring and pressurized liquid extraction (PLE)] and three different solvents (methanol, ethanol and acetone), with five different solvent to water ratios per solvent, were used for extraction. Extracts were analyzed for phenolic content by high‐performance liquid chromatography and Folin–Ciocalteu assays. The yields of phenolic compounds extracted with a pressurized liquid extractor were comparable to or better than those of four classical extraction procedures. Optimum extraction efficiency with PLE was obtained when extractions were performed with four extraction cycles using ethanol–water (50:50, v/v). The amount of apiin (4,5,7‐trihydroxyflavone 7‐apiosylglucoside) and malonylapiin (apigenin malonylapiosylglucoside) isolated from parsley varied with the composition of extraction solvent. Apiin extractability was found to be a maximum when the solvent (ethanol, methanol or acetone) to water ratio was 30:70 (v/v), whereas higher amounts of malonylapiin were isolated with a reverse solvent to water ratio (70:30, v/v). Malonylapiin was not detected when parsley samples were extracted with organic solvent to water ratios of 10:90 (v/v) and 30:70 (v/v). Published in 2006 by John Wiley & Sons, Ltd     

Antioxidative and anti-inflammatory activities of Citrus unshiu peel extracts using a combined process of subcritical water extraction and acid hydrolysis

Antioxidant and in vitro anti-inflammatory activities of citrus (Citrus unshiu) peel extracts and their acid hydrolysates were evaluated. Citrus peel extracts were extracted by subcritical water, hot water, and ethanol. Subcritical water extraction led to extract more phenolic compounds than hot water or ethanol extraction. Acid hydrolysis more than doubled the extracts’ total phenolics and flavonoids. Acid hydrolysates showed greater DPPH-radical scavenging activities and antioxidant activities, as assayed by β-carotene bleaching and ferric thiocyanate, than the initial extracts. Anti-inflammatory activities of citrus peel extracts and hydrolysates, determined by the inhibition of hyaluronidase activity, showed that the inhibition activities of hot water and ethanol extracts increased from 2.1 and 1.8% to 37.0 and 18.5%, respectively, upon acid hydrolysis; however, the anti-inflammatory activity of the subcritical water extract was not improved. These results indicated that acid hydrolysis of citrus peel extracts regardless of their extraction methods improved the antioxidative and anti-inflammatory activities.     

Advances in green solvents for production of polysaccharide-based packaging films: Insights of ionic liquids and deep eutectic solvents

The problems with plastic materials and the good film-forming properties of polysaccharides motivated research in the development of polysaccharide-based films. In the last 5 years, there has been an explosion of publications on using green solvents, including ionic liquids (ILs), and deep eutectic solvents (DESs) as candidates to substitute the conventional solvents/plasticizers for preparations of desired polysaccharide-based films. This review summarizes related properties and recovery of ILs and DESs, a series of green preparation strategies (including pretreatment solvents/reaction media, ILs/DESs as components, extraction solvents of bioactive compounds added into films), and inherent properties of polysaccharide-based films with/without ILs and DESs. Major reported advantages of these new solvents are high dissolving capacity of certain ILs/DESs for polysaccharides (i.e., up to 30 wt% for cellulose) and better plasticizing ability than traditional plasticizers. In addition, they frequently display intrinsic antioxidant and antibacterial activities that facilitate ILs/DESs applications in the processing of polysaccharide-based films (especially active food packaging films). ILs/DESs in the film could also be further recycled by water or ethanol/methanol treatment followed by drying/evaporation. One particularly promising approach is to use bioactive cholinium-based ILs and DESs with good safety and plasticizing ability to improve the functional properties of prepared films. Whole extracts by ILs/DESs from various byproducts can also be directly used in films without separation/polishing of compounds from the extracting agents. Scaling-up, including costs and environmental footprint, as well as the safety and applications in real foods of polysaccharide-based film with ILs/DESs (extracts) deserves more studies.     

An eco-friendly pressure liquid extraction method to recover anthocyanins from broken black bean hulls

This study aimed to recover the anthocyanin-rich extract from broken black bean hulls by pressurized liquid extraction (PLE) and to study their chemical stability, inhibition capacity toward carbohydrate-enzymes and application in gelatin. A Box-Behnken design (BBD) coupled to response surface methodology (RSM) was applied in order to maximize the anthocyanin extraction conditions. Optimum PLE conditions obtained were ethanol:citric acid solution 0.1 mol L⁻¹ (30:70, v/v), a flow rate of 4 mL min⁻¹_, and 60 °C. Delphinidin-3-glucoside was the main anthocyanin quantified. The PLE crude and purified anthocyanin-rich extracts inhibited α-amylase (IC₅₀: 0.52 and 2.85 mg mL⁻¹) and α-glucosidase (0.03 and 0.15 mg mL⁻¹) enzymes, respectively. The PLE anthocyanin-rich extracts showed higher stability in low temperatures and in the absence of light. Besides, the application in gelatin provided a natural color and supplementation with antioxidant compounds. Overall, anthocyanin-rich extract obtained from black bean by-product using an eco-friendly PLE method shows potential as natural colorant and supplement.Industrial relevancePLE method is an emerging technique that performs fast and efficient extractions under high temperature and pressure conditions. The association of green technologies with green solvents makes PLE an eco-friendly technology. This article provides information about the extraction of anthocyanin-rich extracts from the broken black bean hulls by green PLE process under optimized conditions. The process allowed to obtain antioxidant-rich extracts with high application potential in food, supplements, and pharmaceutical industries.     

Optimization of extraction conditions of total phenolics, antioxidant activities, and anthocyanin of oregano, thyme, terebinth, and pomegranate

The purpose of this study was to evaluate the total phenolic extracts and antioxidant activity and anthocyanins of varieties of the investigated plants. These plants include oregano, thyme, terebinth, and pomegranate. The optimum extraction conditions including temperature and solvent of the extraction process itself were investigated. Total phenolic and anthocyanin extracts were examined according to Folin-Ciocalteu assay and Rabino and Mancinelli method, respectively. The effect of different extracting solvents and temperatures on extracts of phenolic compounds and anthocyanins were studied. Plant samples were evaluated for their antioxidant chemical activity by 2, 2-diphenyl-1-picrylhydrazl assay, to determine their potential as a source of natural antioxidant. Results showed that all tested plants exhibited appreciable amounts of phenolic compounds. The methanolic extract (60 °C) of sour pomegranate peel contained the highest phenolic extract (4952.4 mg/100 g of dry weight). Terebinth green seed had the lowest phenolic extract (599.4 mg/100 g of dry weight). Anthocyanins ranged between 3.5 (terebinth red seed) and 0.2 mg/100 g of dry material (thyme). Significant effect of different extracting solvents and temperatures on total phenolics and anthocyanin extracts were found. The methanol and 60 °C of extraction conditions found to be the best for extracting phenolic compounds. The distilled water and 60 °C extraction conditions found to be the best for extracting anthocyanin.     

Antibiofilm effects of pomegranate peel extracts against B. cereus,B. subtilis,and E. faecalis

In this study, the antibacterial and antibiofilm properties of pomegranate (Punica granatum L.) extracts (PPLs) prepared by 10 g of pomegranate peels (PPL10) and 100 mL of different solvents (ethanol, methanol, and their acid combinations, and water) were investigated as sources of bioactive compounds against food-related bacteria. The antimicrobial activities of the extracts were measured by using agar well diffusion assay. The acid-treated extracts exhibited the highest antimicrobial activities (31–34 mm). The biofilm formations were assessed by using a microplate reader (570 nm) after crystal violet staining. The prevention and removal of bacterial biofilms were also evaluated by using extracts prepared by 5 g of initial pomegranate peel (PPL5) with the different solvents or 200 ppm chlorine solution. All PPL5 and PPL10 extracts diluted at different ratios inhibited and removed biofilms, and the highest antibiofilm effects were up to 80% by acid-treated extracts. In addition, PPL5s and PPL10s were as effective as or more effective than chlorine for the prevention of biofilms. Therefore, from an economical perspective the PPL5s could represent promising candidates as natural antibiofilm agents for food industry.     

板栗壳多酚的超声波辅助低共熔溶剂提取工艺优化及其成分分析

采用低共熔溶剂（Deep eutectic solvents,DESs）-超声波辅助提取法对废弃板栗壳中的多酚进行提取并进行成分鉴定。本实验成功合成8种不同的DESs,并用傅里叶红外变换光谱表征氢键供体和氢键受体之间氢键的形成。基于单因素实验,采用响应面法优化超声波功率、液固比、低共熔溶剂水分含量三个因素对总酚得率的影响,经大孔吸附树脂纯化后进行多酚成分鉴定。结果表明,8种DESs中,氯化胆碱-草酸（摩尔比1:1）合成的DES-1总酚得率最高,且明显高于传统溶剂（水和40%乙醇）;最佳提取工艺参数为:超声波功率348 W、液固比42:1 mL/g、水分含量32%,总酚得率为（99.66±2.63） mg/g,与理论总酚得率99.44 mg/g接近,采用AB-8大孔树脂从DESs提取物中回收多酚,回收率高达97.92%±1.78%。UHPLC-ESI-Q-TOF-MS/MS从粗提物中初步鉴定出13种酚类物质。本研究提供了一种绿色、高效的从板栗壳中提取多酚的方法,可为板栗壳废弃物的开发利用提供技术支撑。     

Experimental Design,Modeling, and Optimization of High-Pressure-Assisted Extraction of Bioactive Compounds from Pomegranate Peel

Pomegranate peels are very rich in bioactive compounds, particularly antioxidants, that when properly extracted, may be used for different applications such as food, cosmetics, and pharmaceutics. In this paper, we studied the effect of high-pressure extraction on antioxidant activity and bioactive compounds (total phenolics, tannins, flavonoids, and anthocyanins) of pomegranate peel, using a Box–Behnken design to evaluate the effects of pressure, extraction time, and ethanol concentration to estimate the optimum extraction conditions by response surface methodology (RSM). Individual phenolics, tannins, and anthocyanins were also identified and quantified using the optimum extraction conditions identified by RSM. The results indicated that a quadratic polynomial model could be used to optimize high-pressure extraction of bioactive compounds from pomegranate peel (R ² higher than 0.90). Ethanol concentration was the variable with higher impact and high pressure increased in average 13% the extraction amount of bioactive compounds. The optimum extraction conditions were similar for all compounds (except for anthocyanins) ranging between 356 and 600 MPa, 32 and 56% of ethanol, and 30 min of extraction time. A pressure of 492 MPa, extraction time of 30 min, and an ethanol concentration of 37% were found to result in the highest amount of the quantified individual compounds. Analysis of variance indicated a high goodness of fit of the used models and adequacy of response surface methodology for optimizing high-pressure extraction. The pomegranate peels are industrial by-products that are rich in bioactive compounds and the results obtained in this work show that high pressure is a promising process for scale up of extraction processes. However, pilot plant tests at higher scale will be necessary to ponder the economic viability of the process.     

Extraction of bioactive compounds from Curcuma longa L. using deep eutectic solvents: In vitro and in vivo biological activities

In this work, deep eutectic solvents (DES-based menthol and cholinium chloride) and the ethanol, temperature, and times were selected to extract bioactive compounds from the rhizome, leaves, and flowers Curcuma longa L., using ultrasound-assisted extraction. Analyzes antioxidant, flavonoids, antimicrobial, chelation Fe²⁺, inhibition of the cholinesterase's enzymes, cytotoxicity, and genotoxicity in Allium cepa cells were performed. The extracts showed results of iron chelation and antibacterial. Curcuma flowers and leaves' extracts inhibited food spoilage bacteria with values above 45%, with substantial iron-chelating activity above 50%. Extracts obtained by DES based on menthol and lactic acid exhibited a high percentage of inhibition of acetyl and butyryl cholinesterase. In contrast, flower extracts obtained by menthol and acetic acid showed low inhibition of cholinesterase enzyme activity. No extract showed cytotoxicity and genotoxicity. Biological activities showed a high potential for the application of these extracts in the food and pharmaceutical industries.     

Antioxidant properties of various solvent extracts of potato peel,sugar beet pulp and sesame cake

BACKGROUND: Growing interest in the replacement of synthetic food antioxidants by natural ones has fostered research on vegetable sources and screening of raw materials to identify new antioxidants. The food‐processing industry generates substantial quantities of phenolic‐rich by‐products that could be valuable natural sources of antioxidants. In this study the antioxidant properties and total phenolic, flavonoid and flavonol contents of three industrial by‐products, sugar beet pulp, sesame cake and potato peel, extracted with various solvents were examined. Since different antioxidant compounds have different mechanisms of action, several methods were used to assess the antioxidant efficacy of extracts. RESULTS: Among the six solvents tested, methanol gave the highest extract yield of potato peel and sugar beet pulp, while diethyl ether gave the highest extract yield of sesame cake. Methanol exhibited the highest extraction ability for phenolic compounds, with total phenolics amounting to 2.91, 1.79 and 0.81 mg gallic acid equivalent g^?1 dry weight in potato peel, sugar beet pulp and sesame cake extracts respectively, and also showed the strongest antioxidant capacity in the three assays used. All three methods proved that potato peel extract had the highest antioxidant activity owing to its high content of phenolic compounds and flavonoids. CONCLUSION: On the basis of the results obtained, potato peel, sugar beet pulp and sesame cake extracts could serve as natural antioxidants owing to their significant antioxidant activity. Therefore they could be used as preservative ingredients in the food and/or pharmaceutical industries. Copyright © 2009 Society of Chemical Industry     

Pressurized liquids as an alternative process to antioxidant carotenoids' extraction from Haematococcus pluvialis microalgae

In this work, extraction of antioxidant carotenoids from Haematococcus pluvialis microalga, has been studied combining pressurized liquid extraction (PLE), using hexane and ethanol as extracting solvents, and analytical techniques such as thin layer chromatography (TLC) and HPLC with DAD. The effect of the extraction temperature (50, 100, 150 and 200 °C) and the polarity of the solvent have been studied in terms of in vitro antioxidant activity and chemical composition considering two different morphological cells (green vegetative cells and red cysts). Results demonstrate that the extraction temperature had a positive influence in the extraction yield while its effect in the antioxidant activity was negative, lowering the activity of the extracts with an increase of the extraction temperature. The best yields were obtained with ethanol at the higher extraction temperature while the best antioxidant activity was also achieved using ethanol but at lower temperatures. Chemical composition was determined by TLC and HPLC with DAD. Several compounds were identified in the samples and concentration of astaxanthin was obtained. Results pointed out that the extracts contained different carotenoids in both, the green and the red phase, and that depending on its contribution a stronger antioxidant activity would be expected.     

Pressurized green liquid extraction of betalains and phenolic compounds from Opuntia stricta var. Dillenii whole fruit: Process optimization and biological activities of green extracts

The Opuntia Stricta var. Dillenii's prickly pears are an underutilized fruits, which provide a great source of betalains (mainly, betacyanins) and phenolic compounds (phenolic acids and flavonoids) that could play an important role in health-promotion. This study focuses on the optimization of process for the green extraction of betalains and phenolic compounds from Opuntia stricta var. Dillenii's whole fruits by Pressurized liquid extraction (PLE), using a response surface methodology (RSM) by a central composite design (CCD) in order to obtain rich extracts in betalains and phenolic compounds with the similar profile of the original one found in O. dillenii fruits (avoiding any degradation of these compounds during the extraction process) with proven biological activities. For PLE optimization, the ethanol volume in water (0–100%, v/v) and the temperature (25–65°C) were selected as independent variables. The identification and quantification of the individual bioactive compounds of the obtained green extracts were done by HPLC-DAD-ESI/MS and HPLC-DAD-ESI/QTOF and their biological activities were determined by in vitro tests, as: the antioxidant activity by the ORAC method and the anti-inflammatory activity by the hyaluronidase inhibition method. Ethanol volume in water (%, v/v) was the variable with most significant (p ≤ 0.05) effect in the target responses (bioactive content and biological activities). The best results were obtained at 50% ethanol in water (v/v) and 25°C temperature (run 10) obtaining extracts with betalains as 2.34 ± 0.18 mg of betanin/g dry weight, 2.51 ± 0.04 mg of 5′´-O-E-sinapoyl-2′-apyosil-phyllocactin/g dry weight, 2.32 ± 0.19 mg of neobetanin/g dry weight and phenolic compounds, 2.08 ± 0.07 mg of piscicid acid/g dry weight and 0.25 ± 0.02 mg of isorhamnetin glucoxyl-rhamnosyl-pentoside (IG2) /g dry weight. The betalain and phenolic profile of the PLE extracts was quite similar to the profile from the conventional extraction, but PLE extraction process enhanced the extraction of some bioactives as neobetanin (39%) andpiscidic acid (124%). All employed PLE process CCD combinations significantly upgrade the in vitro biological activities (antioxidant and anti-inflammatory) of the Opuntia stricta var. Dillenii's PLE green extracts.     

Green Extraction Methods for Polyphenols from Plant Matrices and Their Byproducts: A Review

Polyphenols as phytochemicals have gained significant importance owing to several associated health benefits with regard to lifestyle diseases and oxidative stress. To date, the development of a single standard method for efficient and rapid extraction of polyphenols from plant matrices has remained a challenge due to the inherent limitations of various conventional extraction methods. The exploitation of polyphenols as bioactive compounds at various commercial levels has motivated scientists to explore more eco‐friendly, efficient, and cost‐effective extraction techniques, based on a green extraction approach. The current review aims to provide updated technical information about extraction mechanisms, their advantages and disadvantages, and factors affecting efficiencies, and also presents a comparative overview of applications of the following modern green extraction techniques—supercritical fluid extraction, ultrasound‐assisted extraction, microwave‐assisted extraction, pressurized liquid extraction, and pressurized hot water extraction—as alternatives to conventional extraction methods for polyphenol extraction. These techniques are proving to be promising for the extraction of thermolabile phenolic compounds due to their advantages over conventional, time‐consuming, and laborious extraction techniques, such as reduced solvent use and time and energy consumption and higher recovery rates with lower operational costs. The growing interest in plant‐derived polyphenols prompts continual search for green and economically feasible modern extraction techniques. Modern green extraction techniques represent promising approaches by virtue of overcoming current limitations to the exploitation of polyphenols as bioactive compounds to explore their wide‐reaching applications on an industrial scale and in emerging global markets. Future research is needed in order to remove the technical barriers to scale‐up the processes for industrial needs by increasing our understanding and improving the design of modern extraction operations.     

Recovery of Aromatic Aglycones from Grape Pomace Winemaking By-Products by Using Liquid-Liquid and Pressurized-Liquid Extraction

The potential of winemaking grape pomace by-products as a source of glycosidic aroma precursors that under enzymatic hydrolysis might release aroma compounds has been evaluated. Two different extraction methodologies, liquid–liquid and pressurized liquid extraction (LLE and PLE) were employed. Solid phase extraction (SPE)-GC-MS analysis of the hydrolyzed LLE glycosidic extract revealed 22 aroma compounds belonging to different chemical families (terpenes, C13 norisoprenoids, vanillines, etc.). Response surface methodology was employed to study the effect of the most significant PLE experimental variables (temperature and solvent composition) on the extraction of aromatic aglycones. The parameters of the model were estimated by multiple linear regressions. Most of the aroma compounds showed an adequate fit to the calculated model (18 compounds from 22 with R ²?>?0.8). The application of the optimized PLE conditions (50 % of ethanol in the hydroalcoholic solution) and 90 °C showed higher extraction yield of aglycones when comparing with the extraction yield obtained by LLE.     

Column-chromatographic extraction and separation of polyphenols, caffeine and theanine from green tea

A highly efficient column-chromatographic extraction (CCE) followed by sequential adsorption to extract and separate bioactive compounds from green tea was developed. Tea powder was loaded into columns with 4-fold solvents and eluted through a cyclic CCE. High-quality tea extracts with greater than 90% extraction efficiencies of polyphenols, epigallocatechin-3-gallate, caffeine, theanine and polysaccharides were obtained with 4-fold water circulated five times among different columns at 70 °C. Similar results, except for low polysaccharide extraction (35.5%), were obtained with 4-fold 30% ethanol circulated three times at room temperature. The highly concentrated water extraction was directly passed through columns of polyamide, DM130 macroporous and 732 ion exchange resins, resulting in high-purity polyphenols (99%), caffeine (98%) and theanine (98%) after simple purification of the eluates from each column. This method uses simple equipment, minimum solvents and can be used for both quantitative analysis and continuous preparation of high-quality tea extracts and bioactive compounds.