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Grape pomace (GP) is a by-product rich in phytochemicals, including extractable polyphenols (EPPs) and non-extractable polyphenols (NEPPs), which have distinct metabolic fates that may affect their biological activities. The benefits of GP have been reported in relation to obesity and its comorbidities, particularly when administered preventively focusing on EPPs. Therefore, the aim of this study was to investigate the effects of EPPs and NEPPs from GP as a treatment for obesity and its associated metabolic alterations. A previous comprehensive characterization of the selected GP revealed the most relevant individual compounds in the EPPs fraction (malvidin hexoside, (-)-epicatechin, quercetin, and procyanidin dimer B2 isomer II), as well as in the NEPPs fraction (hydroxybenzoic acid isomers I-II). The experiment was performed in obese rats with insulin resistance, treated for 8 weeks with EPPs or NEPPs grape pomace fractions (100 mg/kg). After the intervention, the HFFD + EPP group showed a significantly lower weight gain (9.6%) and body mass index (9.7%) compared to the HFFD group. While liver triglyceride levels were only significantly reduced in the HFFD + NEPP group (47%) compared to the HFFD group. Neither treatment resulted in a reduction of insulin resistance. Therefore, the supplementation with grape pomace phenolic fractions to an animal model of obesity exerted differential beneficial effects on body weight and liver lipid accumulation, overall contributing to an amelioration of some the metabolic alterations present in obesity, although not to aspects such as glycemic homeostasis. [ABSTRACT FROM AUTHOR]

Most of the pertinent research which aims at exploring the therapeutic effects of polyphenols usually misapprehends a large fraction of non-extractable polyphenols due to their poor aqueous-organic solvent extractability. These polymeric polyphenols (i.e., proanthocyanins, hydrolysable tannins and phenolic acids) possess a unique property to adhere to the food matrix polysaccharides and protein sowing to their structural complexity with high glycosylation, degree of polymerization, and plenty of hydroxyl groups. Surprisingly resistance to intestinal absorption does not hinder its bioactivity but accelerates its functionality manifolds due to the colonic microbial catabolism in the gastrointestinal tract, thereby protecting the body from local and systemic inflammatory diseases. This review highlights not only the chemistry, digestion, colonic metabolism of non-extractable polyphenols (NEPP) but also summarises the synergistic effect of matrix-bound NEPP exerting local as well as systemic health benefits.

Grape pomace is a commonly discarded by-product characterized by high extractable (EPP) and non-extractable (NEPP) polyphenol contents which exhibits anti-obesogenic effects. However, the relevance of each fraction needs to be elucidated. In this work, we examined the effects of three pomaces with different concentrations of EPPs and NEPPs on metabolic alterations associated with obesity. The NEPP:EPP ratio of the grape pomaces was 1.48 for Malbec, 1.10 for Garnacha, and 5.76 for Syrah grape varieties. Rats fed a high-fat high-fructose diet supplemented with Malbec grape pomace (HFFD + MAL) Syrah grape pomace (HFFD + SYR) or Garnacha grape pomace (HFFD + GAR) showed significantly less weight gain: 20%, 15%, and 12% less, respectively, compared to HFFD controls. The adiposity index was also significantly decreased by 20% in the HFFD + MAL and HFFD + SYR groups, and by 13% in the HFFD + GAR group. Serum triglycerides were significantly decreased by 46% in the HFFD + MAL group and by 31% in the HFFD + GAR group, compared to the HFFD group, but not in the HFFD + SYR group. All pomace supplementations regulated postprandial glucose in an oral glucose tolerance test. Therefore, grape pomaces containing both EPPs and NEPPs exert beneficial effects on body weight and glucose homeostasis, while EPPs seem to control triglyceride levels more effectively. [ABSTRACT FROM AUTHOR]

In the past few years, numerous studies have investigated the correlation between polyphenol intake and the prevention of several chronic diseases. Research regarding the global biological fate and bioactivity has been directed to extractable polyphenols that can be found in aqueous-organic extracts, obtained from plant-derived foods. Nevertheless, significant amounts of non-extractable polyphenols, closely associated with the plant cell wall matrix (namely with dietary fibers), are also delivered during digestion, although they are ignored in biological, nutritional, and epidemiological studies. These conjugates have gained the spotlight because they may exert their bioactivities for much longer than extractable polyphenols. Additionally, from a technological food perspective, polyphenols combined with dietary fibers have become increasingly interesting as they could be useful for the food industry to enhance technological functionalities. Non-extractable polyphenols include low molecular weight compounds such as phenolic acids and high molecular weight polymeric compounds such as proanthocyanidins and hydrolysable tannins. Studies concerning these conjugates are scarce, and usually refer to the compositional analysis of individual components rather than to the whole fraction. In this context, the knowledge and exploitation of non-extractable polyphenol-dietary fiber conjugates will be the focus of this review, aiming to access their potential nutritional and biological effect, together with their functional properties. [ABSTRACT FROM AUTHOR]

Highland barley bran (HBB) is rich in extractable polyphenols (EP) and non-extractable polyphenols (NEP). Previous studies have generally used chemical solvents to extract EP and NEP and assess their functional properties. However, EP and NEP obtained using chemical method do not indicate phenolic compounds profiles released in the body. This study used chemical (acetone and acid hydrolysis) and physiological methods (in vitro gastrointestinal digestion and colonic fermentation) to treat HBB and investigated the differences between the two methods in releasing EP and NEP. Results showed that chemical method yielded a higher total phenolic content (EP + NEP = 718.25 mg GAE/100 g) than physiological method (634.62 mg GAE/100 g). More phenolic compounds, particularly ferulic acid oligomers, were released by chemical method and exhibited stronger total antioxidant capacities than those released by physiological method. Moreover, structural analysis indicated two methods used different mechanisms to release EP and NEP, with chemical method releasing polyphenols by drastically disrupting the cellular structure of the aleurone layer and physiological method releasing polyphenols by degrading cell walls. Therefore, a possible release mechanism was proposed. These findings highlight the importance of physiological method in accurately reflecting polyphenol bioaccessibility, which is critical for evaluating their potential health benefits. • Physiological and chemical methods were used to release EP and NEP. • Chemical method completely released EP and NEP compared to physiological method. • The phenolic profiles of EP and NEP released by the two methods were different. • Two methods had different degrees of destructive effect on the aleurone layer. • Two methods used different mechanisms to release EP and NEP. [ABSTRACT FROM AUTHOR]

[Display omitted] • LEH-U was the best extraction method for extracting NEPPs from Undaria pinnatifida. • Phenolic acids were the major polyphenols in ULNEPPs. • ULNEPPs regulated glucose metabolism by PI3K/AKT/FOXO1 and AMPK/PGC-1α/GLUT4 pathways. Undaria pinnatifida (Up) is an edible seaweed known for its abundant nutrients and active compounds. In this research, six different methods, including acid hydrolysis extraction (AHE), alkaline hydrolysis extraction (LHE), enzymatic hydrolysis extraction (EHE), as well as their combinations with ultrasonic assisted extraction (AHE-U, LHE-U, EHE-U), were applied to extract non-extractable polyphenols from Up (UNEPPs). Results revealed that LHE-U was the most effective way to extract UNEPPs, it gave the highest yield (1.26 %) and total phenolics content (29.88 μg GAE/mg E), as well as considerable antioxidant and in vitro hypoglycemic effects. HPLC-Q-TOF-MS/MS analysis revealed the identification of 36 compounds from ULNEPPs, ferulic acid, p-coumaric acid and ferulic acid 4-O-glucuronide were the major compounds. In vivo study found that ULNEPPs could reduce fasting blood glucose (FBG) level, ameliorate abnormal glucose metabolism and dyslipidemia, repair insulin resistance and pancreas islet damage in type 2 diabetes (T2D) mice. Additionally, RT-qPCR analysis revealed that ULNEPPs improved glucose metabolism through the up-regulation of gene expression levels of Pi3k , Glut4 , Akt , Ampk and the down-regulation of gene expression levels of Foxo1 , Pgc-1α , Gsk-3β , Glut4 , and G6pc. These results evidence that has the potential as dietary ingredients for preventing and treating T2D. [ABSTRACT FROM AUTHOR]

Spent black tea (SBT) is a residue from tea beverage production and considered as a potential source of active polyphenols. This study aimed to develop a pilot-scale process on semi-continuous subcritical solvent extraction (SSE) of polyphenols from SBT by exploiting the lab-scale knowledge. Treatment of SBT with ethanol–water (50% w/w) as solvent at 125 °C and 0.3 MPa achieved a significantly higher yield of polyphenols (80.82 g gallic acid equivalents/kg black tea) with antioxidant activity (64.20 g gallic acid equivalents/kg black tea), compared to hot water extraction (HWE). SSE increased the soluble matter content in extracts than HWE. Based on the results of LC-MS, theaflavin-3,3′-digallate was the most abundant polyphenol from a total of 12 compounds to be extracted by SBT with 50% ethanol. The results suggested that SSE can be used as a scale-up extraction method to recover polyphenols from SBT.

In the past few years, numerous studies have investigated the correlation between polyphenol intake and the prevention of several chronic diseases. Research regarding the global biological fate and bioactivity has been directed to extractable polyphenols that can be found in aqueous-organic extracts, obtained from plant-derived foods. Nevertheless, significant amounts of non-extractable polyphenols, closely associated with the plant cell wall matrix (namely with dietary fibers), are also delivered during digestion, although they are ignored in biological, nutritional, and epidemiological studies. These conjugates have gained the spotlight because they may exert their bioactivities for much longer than extractable polyphenols. Additionally, from a technological food perspective, polyphenols combined with dietary fibers have become increasingly interesting as they could be useful for the food industry to enhance technological functionalities. Non-extractable polyphenols include low molecular weight compounds such as phenolic acids and high molecular weight polymeric compounds such as proanthocyanidins and hydrolysable tannins. Studies concerning these conjugates are scarce, and usually refer to the compositional analysis of individual components rather than to the whole fraction. In this context, the knowledge and exploitation of non-extractable polyphenol-dietary fiber conjugates will be the focus of this review, aiming to access their potential nutritional and biological effect, together with their functional properties.

Grape pomace is a commonly discarded by-product characterized by high extractable (EPP) and non-extractable (NEPP) polyphenol contents which exhibits anti-obesogenic effects. However, the relevance of each fraction needs to be elucidated. In this work, we examined the effects of three pomaces with different concentrations of EPPs and NEPPs on metabolic alterations associated with obesity. The NEPP:EPP ratio of the grape pomaces was 1.48 for Malbec, 1.10 for Garnacha, and 5.76 for Syrah grape varieties. Rats fed a high-fat high-fructose diet supplemented with Malbec grape pomace (HFFD + MAL) Syrah grape pomace (HFFD + SYR) or Garnacha grape pomace (HFFD + GAR) showed significantly less weight gain: 20%, 15%, and 12% less, respectively, compared to HFFD controls. The adiposity index was also significantly decreased by 20% in the HFFD + MAL and HFFD + SYR groups, and by 13% in the HFFD + GAR group. Serum triglycerides were significantly decreased by 46% in the HFFD + MAL group and by 31% in the HFFD + GAR group, compared to the HFFD group, but not in the HFFD + SYR group. All pomace supplementations regulated postprandial glucose in an oral glucose tolerance test. Therefore, grape pomaces containing both EPPs and NEPPs exert beneficial effects on body weight and glucose homeostasis, while EPPs seem to control triglyceride levels more effectively.

The white Lupin (Lupinus albus) is a legume of the genus Lupinus, originally from the Mediterranean region, prominent nutritional value, due to your high level of dietary fiber, carbohydrates, proteins and lipids balanced profile. In addition, it has bioactive compounds, mainly polyphenols, with significant antioxidant capacity. Even if the present low level of white Lupin alkaloids, as the lupanine, yet the presence of these compounds can be a limiting factor for your consumption. However, despite being an antinutricional factor, possible effect antihypertensive and anti-hiperglicemic of lupanine are being reported. In this way, this work aimed to evaluate the content of total polyphenols (extractable and macromolecular), antioxidant capacity and identify the presence of lupanine in white Lupin beans, subjected or not to heat treatment. Quantification of polyphenols was carried out by the Folin-Ciocalteau assay, antioxidant activity tests TEAC and DPPH and lupanine identification by gas chromatography coupled to mass spectrometry. In all samples analysed, it was possible to identify the lupanine. The levels of total polyphenols found in control and treated thermally samples were 6142,50 and 6418,44 (mg GAE/100 g), respectively. With respect to the antioxidant capacity of the Lupine the EC50 ranged from 3473,49 ± 201,98 to 3832,65 ± 235,87 (g sample/g DPPH). Using the ABTS radical, the antioxidant activity presented values TEAC that ranged from 250,14 ± 14,32 to 270,39 ± 8,37 (µM trolox/g sample). Greater antioxidant capacity was linked to macromolecular polyphenols. Heat treatment did not interfere in the contents of polyphenols and antioxidant capacity of white Lupin beans.

Mangosteen (Garcinia mangostana L.) peel is a potential source of phenolic compounds with beneficial properties. Natural deep eutectic solvents (NaDES) have been considered an environmentally friendly and cheap alternative to conventional organic solvents. In this work, a green extraction methodology was developed using ultrasound-assisted extraction (UAE) and NaDES for the extraction of antioxidant non-extractable polyphenols (NEPs) from mangosteen peel. To select the best NaDES to extract NEPs from mangosteen peel, seven NaDES were studied. Antioxidant capacity and total phenolic and proanthocyanidin contents were determined for the extracts. The molecular weights for the NEPs present in those extracts were evaluated by size exclusion chromatography. Experimental results showed that choline chloride–lactic acid (1:2) was the NaDES allowing the highest antioxidant proanthocyanidin content in the extracts. A Box–Behnken experimental design was employed to optimize the main parameters in UAE with NaDES: water percentage, ultrasound amplitude, and extraction time. The optimal extraction conditions were 18.8% (v/v) water, 60% ultrasound amplitude, and 15 min as the extraction time. In addition, the cytotoxicity of the NEP extracts obtained under optimal extraction conditions was evaluated. Results indicated for the first time that the use of NaDES in combination with UAE could be a sustainable alternative for the extraction of antioxidant NEPs from mangosteen peel for important applications in the food, pharmaceutical, agrochemical, and cosmetic fields, as the extracts presented low cytotoxicity. [ABSTRACT FROM AUTHOR]

Mulberry is a health-promoting fruit with abundant phenolic compounds. The effects of vacuum drying (VD) and vacuum freeze-drying (VFD) on oxidation resistance and polyphenols, including extractable and non-extractable phenols, were compared in the present work. The total polyphenols and antioxidant capacity of mulberry fruits treated with VFD were higher than those treated with VD. Thirteen phenolic compounds in fresh and dried mulberry fruits were identified and quantified by UPLC-QqQ/MS. The content of extractable phenol was significantly higher than that of non-extractable phenol. In addition, correlation analysis showed that flavonoids cyanidin-3-O-glucoside and phloretin were closely related to the total polyphenols and antioxidant activity. These results provide the basis for further development of dried mulberry products containing high contents of total polyphenols and antioxidant activity. [ABSTRACT FROM AUTHOR]

In recent times, research has highlighted the bioactive roles played by non-extractable polyphenols (NEP) in human health, especially from by-products of grains, fruits and vegetables. Most studies have reported on the total phenol content of samples without adequate attention paid to a major class of polyphenols referred to as NEP. This limits the scope of polyphenol studies and the extent of NEP incorporation into medicines, nutraceuticals, cosmetic and foods among other applications. This review introduces NEP and gives an update on recent advances in free and bound polyphenol extraction from plant by-products. Owing to the fact that most researchers are already familiar with the extraction of free polyphenols, this review emphasizes the extraction of NEP and provides a basis for the selection of appropriate techniques and applications for different plant by-product sources. It also presents suggestions for future studies into NEP extraction efficiency from complex plant sources using alternative physical approaches. NEP from by-products have high potential for use in industry, especially in pharmaceutical, nutraceutical and cosmetic applications. To ascertain the total phenol content of extracts, both free and bound phenols must be accounted for with special attention directed at appropriate sample pretreatment and extract hydrolysis. Higher bioactive properties of NEP, coupled with their cheaper by-product sources makes them economically viable and medicinally potent. Also, structure-function relationships and the possibility to use physical means such as slow-freezing-thawing to increase hydrolytic yield of NEP is recommended. Image 1 • Total phenol content of extracts does not mostly give true accounts of all phenols. • Bound and free polyphenols together describe total phenols in extracts. • Bound polyphenols have high bioactive properties for industrial applications. • Hydrolytic treatment of plant materials allows easier recovery of polyphenols. • Physical, slow freeze-thaw mechanism is suggested for future studies. [ABSTRACT FROM AUTHOR]

Mangosteen (Garcinia mangostana L.) peel is a potential source of phenolic compounds with beneficial properties. Natural deep eutectic solvents (NaDES) have been considered an environmentally friendly and cheap alternative to conventional organic solvents. In this work, a green extraction methodology was developed using ultrasound-assisted extraction (UAE) and NaDES for the extraction of antioxidant non-extractable polyphenols (NEPs) from mangosteen peel. To select the best NaDES to extract NEPs from mangosteen peel, seven NaDES were studied. Antioxidant capacity and total phenolic and proanthocyanidin contents were determined for the extracts. The molecular weights for the NEPs present in those extracts were evaluated by size exclusion chromatography. Experimental results showed that choline chloride–lactic acid (1:2) was the NaDES allowing the highest antioxidant proanthocyanidin content in the extracts. A Box–Behnken experimental design was employed to optimize the main parameters in UAE with NaDES: water percentage, ultrasound amplitude, and extraction time. The optimal extraction conditions were 18.8% (v/v) water, 60% ultrasound amplitude, and 15 min as the extraction time. In addition, the cytotoxicity of the NEP extracts obtained under optimal extraction conditions was evaluated. Results indicated for the first time that the use of NaDES in combination with UAE could be a sustainable alternative for the extraction of antioxidant NEPs from mangosteen peel for important applications in the food, pharmaceutical, agrochemical, and cosmetic fields, as the extracts presented low cytotoxicity.

• Olive pomace (OP) was fractionated in 2-mm sieve and micronized in a ball mill. • OP fraction < 2 mm was enriched in soluble fiber and polyphenols as hydroxytyrosol. • Rapid micronization reduces OP particle size and improves polyphenols' extraction. • Fractionation and micronization (˜30 μm) increase OP antioxidant capacity. This study was aimed to evaluate the effect of micronization of granulometrically fractioned olive pomace (OP) on the content of extractable polyphenols (EPP), non-extractable polyphenols (NEPP) and its antioxidant capacity. Crude OP was separated in 2-mm sieve, resulting in two fractions: F1 (> 2 mm) and F2 (< 2 mm). F2 had higher content of ash, fat, soluble dietary fiber, EPP, hydrolyzable tannins (HT) and condensed tannins (CT) than F1. F1 and F2 fractions were defatted and submitted to a micronization process using a factorial design 22 (variables: rotational speed and milling time) with EPP as response. The optimal micronizing conditions, 500 rpm/24.8 min for the F1 and 500 rpm/16 min for the F2, reduced particle size to around 30 μm. Micronization increased the content of EPP and HT in F1 and F2. Granulometric fractionation and micronization were effective to increase EPP content and antioxidant capacity of OP. [ABSTRACT FROM AUTHOR]

Non-extractable polyphenols (NEP) are polyphenols that are bound to dietary fibre (DF) and have important health benefits to humans. Past studies have used hydrolysis methods to extract NEP, studying NEP and DF separately. However, hydrolysis may affect their structures and functional properties. In fact, DF is a carrier of NEP in foods, and they physically and/or chemically interact with each other and exist as a complex, known as "antioxidant dietary fibre (ADF)". Therefore, the review focuses on the natural structure: ADF. The food matrix is a complex system with multiple components, and it is very important to explore approaches to obtain ADF and the effect of its structure on functional properties. This review summarizes methods for isolating ADF from samples or forming it in vitro , as well as structural characterization, and discusses the functional implications arising from ADF. The ADF structure, especially the interactions between NEP and DF, has been characterized. Covalent interactions have been identified in the isolated ADF, and non-covalent interactions are the primary driving force in formed ADF. ADF is bioaccessible and bioavailable, has prebiotic, antioxidant, and anti-inflammatory properties. The structures of ADF, such as the structures and compositions of NEP and DF and their interactions, have a significant role in its functional properties. This review highlights the importance of ADF and provides structure-function information, which will contribute to future studies on its health benefits and the development of functional foods. [Display omitted] • NEP and DF are not independent compounds and have mutual effects. • ADF can be isolated from samples or formed in vitro. • Covalent and non-covalent interactions exist between NEP and DF. • NEP and DF exert synergistic/complementary effects yet other independent effects. • The functional properties of ADF are affected by its structure. [ABSTRACT FROM AUTHOR]

Despite increasing interest in the relevance of non-extractable polyphenols (NEPP) or macromolecular antioxidants as food bioactive compounds, most studies on their presence in foods focus mainly on the edible part of specific fruits, but their potential presence in fruit peels is usually ignored. The aim of this study was to evaluate NEPP content in the peels from ten common fruits. The results showed that NEPP made up more than half of the total polyphenol contents in half of the studied samples. HPLC analysis showed that NEPP were constituted by phenolic acids, flavanols and flavonols. Also, it was found that peels accounted for >40% of total NEPP in the fruit in four of the samples analysed. These results should encourage both the use of fruit peels in the fruit industry as ingredients and the consumption of whole fruits given the significant presence of NEPP in fruit peels. [ABSTRACT FROM AUTHOR]

The majority of studies based on phenolic compounds from plants are focused on the extractable fraction derived from an aqueous or aqueous-organic extraction. However, an important fraction of polyphenols is ignored due to the fact that they remain retained in the residue of extraction. They are the so-called non-extractable polyphenols (NEPs) which are high molecular weight polymeric polyphenols or individual low molecular weight phenolics associated to macromolecules. The scarce information available about NEPs shows that these compounds possess interesting biological activities. That is why the interest about the study of these compounds has been increasing in the last years. Furthermore, the extraction and characterization of NEPs are considered a challenge because the developed analytical methodologies present some limitations. Thus, the present literature review summarizes current knowledge of NEPs and the different methodologies for the extraction of these compounds, with a particular focus on hydrolysis treatments. Besides, this review provides information on the most recent developments in the purification, separation, identification and quantification of NEPs from plants. [ABSTRACT FROM AUTHOR]

BACKGROUND The impact of high-pressure processing ( HPP) on the polyphenol ( PP) content and antioxidant activity ( AOX) of plantain pulp was evaluated. Pressures of 400, 500 and 600 MPa were applied to plantain pulp for 90 and 180 s at room temperature (25 °C). Polyphenoloxidase activity, extractable ( EPP) and non-extractable PP ( NEPP) contents, flavonoid content and AOX ( FRAP, ABTS•+) were evaluated. In addition, PP identification was performed using high-performance liquid chromatography. RESULTS Polyphenoloxidase activity was inhibited after HPP under all of the conditions studied. Increases of 110.80% and 137.40% in EPP content under conditions of 500 MPa/180 s and 600 MPa/90 s were observed with a simultaneous improvement in the AOX with increments of up to 128.71%. The treatment under conditions of 500 MPa/90 s had the highest total PP content, including the highest content of flavonoids (0.22 g ellagic acid equivalents kg−1 dry weight) and the proportion of NEPP that contained hydrolysable PPs (91.12 g gallic acid equivalents kg−1 dry weight with high AOX. The identified PPs included catechin, quercetin, gallic and hydroxybenzoic acids. CONCLUSION HPP performed at a room temperature can be used for improving the total content of PP compounds in plantain pulp under specific pressure and time conditions. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Introduction: (Poly)phenols (PPs) are plant secondary metabolites widely distributed in dietary sources, and several evidences show that consumption of PP has a positive impact in human health. However, the correct estimation of food intake and the estimation of PP content of foods are essential to associate PPs intake with health effects. Purpose: This review aimed to gather information from several studies on PP intake in different countries, compare methods used for both assessment of food intake and PP quantification and highlight existing gaps and future directions. Methods: Twenty-four studies of PP intake from thirteen countries were selected for analysis. The selected studies included assessment of all plant food groups contributing to PP intake, total PP content and/or content of major classes (flavonoids or phenolic acids), a large study population and both genders. Results and Conclusion: Most studies presented daily intakes of extractable (poly)phenols. Very few studies have determined intake of non-extractable (poly)phenols, which is a very important fraction of PPs contributing to total PP intake. High heterogeneity was observed among countries regarding the intake of total PP intake and the two main PP classes. This may reflect not only different diet patterns, but also different methods used for collecting food consumption data and estimation of PP content. Thus, criteria of harmonization are suggested regarding assessment of food intake, determination of PP content in foods and validation with biomarkers. [ABSTRACT FROM AUTHOR]

This contribution proposes an enzyme-assisted eco-friendly process for the extraction of non-extractable polyphenols (NEPPs) from black tea leftover (BTLO), an underutilized tea waste. BTLO hydrolyzed with various enzyme formulations was extracted using supercritical carbon dioxide and ethanol as co-solvent (SC-CO + EtOH). A conventional solvent extraction (CSE) was performed using EtOH + HO (80:20, v/ v) for comparison purposes. The results revealed that hydrolysis of BTLO with 2.9% ( w/ w) kemzyme at 45 °C and pH 5.4 for 98 min improved the liberation of NEPPs offering 5-fold higher extract yield (g/100 g) as compared with non-treated BTLO. In vitro antioxidant evaluation and LC-MS characterization of extracts revealed the presence of phenolic acids (mainly caffeic and para-coumaric acid) of high antioxidant value. Scanning electron micrograph of the hydrolyzed BTLO samples indicated noteworthy changes in the ultrastructure of BTLO. Moreover, polyphenol extracts obtained by SC-CO + EtOH extraction were found to be cleaner and richer in polyphenols as compared to CSE. The devised enzyme-assisted SC-CO + EtOH extraction process in the present work can be explored as an effective biotechnological mean for the optimal recovery of antioxidant polyphenols. [ABSTRACT FROM AUTHOR]

The contents of extractable polyphenols (EPP), non-extractable polyphenols (NEPP), extractable proanthocyanidins (EPAC), non-extractable proanthocyanidins (NEPAC) and extractable anthocyanidins (EAC) in blueberry leaves were investigated. An experiment was conducted to analyse the effect of solvent types (methanol and ethanol), concentration (50 and 70%) and pH (2 and 6) on the extraction of bioactive compounds. Total extractable polyphenols (TEPP), total extractable proanthocyanidins (TEPAC), and total extractable anthocyanidins (TEAC) were analysed in methanol/ethanol/water extracts, NEPP were determined in acidic hydrolysates and NEPAC were quantified by depolymerisation in HCl/butanol. The results showed that ethanol and methanol did not affect the extraction of TEPP, while methanol was better for TEPAC and TEAC. The contents of TEPP and TEAC in 50% solvent were higher than those in 70% solvent. When solvent pH dropped to 2, the contents of EPP and EPAC were increased, while the EAC content was decreased.

Hungarian sour cherries (SC) are excellent source of anthocyanin (concentrations (100⁻300 mg in 100 g fresh fruit) and melatonin (0.15 mg in 100 g fresh fruit), but other flavonoid derivatives also can be isolated by aqueous alcoholic extraction. We have developed a new process for extracting non-extractable procyanidines bound to the membrane, proteins, and fibers. These compounds were seperated with UHPLC-MS methods, and the structure of individual components were identified on the basis of their mass fragmentation spectra. The antioxidant capacity of soluble and non-soluble antioxidants were measured with ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (DPPH), trolox equivalent antioxidant capacity (TEAC) assays, and compared to the new measurement methods of water-soluble antioxidant capacity (ACW), lipid-soluble antioxidant capacity (ACL). Furthermore, total phenolic content (TPC) and total procyanidin content (PAC) were determinated. As a result of our investigation, we found that the solvent combination, where in the first step is water⁻ethanol (1:1), then 100% ethanol were suitable for the extraction of the extractable antioxidants. However, the chemiluminescence method that is based on the elimination of the superoxide radical is more accurate than other colorimetric methods which measure antioxidant capacity.

BACKGROUND Plant polyphenols are rich in blueberries that have a wide range of properties beneficial to human health. There are two types, according to the solubility of polyphenols, which were defined as extractable polyphenols ( EPP) and non-extractable polyphenols ( NEPP), respectively. At present, in most of reports, 'total polyphenol' refers only to EPP excluding NEPP. In this paper, the effects of EPP and NEPP on lipopolysaccharides ( LPS) induced production of nitric oxide ( NO) and gene expression of inducible NO synthase ( iNOS) and cyclooxygenase-2 ( COX-2) in RAW264.7 cells via nuclear factor- κB ( NF-κB) signalling pathway were compared. RESULTS The results showed that EPP and NEPP from blueberries significantly inhibited the LPS-induced production of NO and gene expression of iNOS and COX-2 in cells. The constitutive level of p65 sub-unit of NF-κB was obviously detected after the treatments with EPP or NEPP. By contrast, the level of phosphorylated p65 (P-p65) was strongly inhibited by EPP or NEPP. EPP had a stronger inhibition on the gene expression of iNOS and COX-2 than that of NEPP. CONCLUSION These findings of inhibition of iNOS and COX-2 mRNA expression through the suppression of NF-κB suggest that EPP and ENPP from blueberries have significant anti-inflammatory effect and may be a potential medicine. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

There is a growing need for a global consensus on the definition of dietary fibre and the use of appropriate methodologies for its determination in different food matrices. Oligosaccharides (prebiotic effect) and bioactive compounds (antioxidant effect) are important constituents of dietary fibre, which enhance its beneficial effects in the body, such as those related to maintaining intestinal health. These dietary components need to be quantified and addressed in conjunction with fibre in nutritional studies due to the close relationship between them and their common destiny in the human body. This review discusses updates to the concept of dietary fibre, with an emphasis on biological and methodological aspects, and highlights the physiological importance of fibre as a carrier of bioactive compounds. [ABSTRACT FROM AUTHOR]

Epidemiological and clinical studies show that diets with a high antioxidant capacity, such us those rich in plant food and beverages, are associated with significant decreases in the overall risk of cardiovascular disease or colorectal cancer. Current studies on dietary antioxidants and dietary antioxidant capacity focus exclusively on low molecular weight or soluble antioxidants (vitamins C and E, phenolic compounds and carotenoids), ignoring macromolecular antioxidants. These are polymeric phenolic compounds or polyphenols and carotenoids linked to plant food macromolecules that yield bioavailable metabolites by the action of the microbiota with significant effects either local and/or systemic after absorption. This study determined the antioxidant capacity of the Spanish Mediterranean diet including for the first time both soluble and macromolecular antioxidants. Antioxidant capacity and consumption data of the 54 most consumed plant foods and beverages were used. Results showed that macromolecular antioxidants are the major dietary antioxidants, contributing a 61% to the diet antioxidant capacity (8000 μmol Trolox, determined by ABTS method). The antioxidant capacity data for foods and beverages provided here may be used to estimate the dietary antioxidant capacity in different populations, where similar contributions of macromolecular antioxidants may be expected, and also to design antioxidant-rich diets. Including macromolecular antioxidants in mechanistic, intervention and observational studies on dietary antioxidants may contribute to a better understanding of the role of antioxidants in nutrition and health. [ABSTRACT FROM AUTHOR]

Macromolecular antioxidants or non-extractable polyphenols are an emerging and ignored fraction of dietary antioxidants that present differential structural and physiological features as compared with the well-known extractable polyphenols. In this study, the macromolecular antioxidant content and profile were determined by the first time for the 24 most consumed fruit and vegetables in four European countries (France, Germany, The Netherlands and Spain). Results showed that macromolecular antioxidants, made up of hydolysable polyphenols and polymeric proanthocyanidins, are major contributors (mean value 57%) to the total polyphenol content of fruit and vegetables. Macromolecular antioxidant intake from fruit and vegetable determined in the four countries selected was about 200 mg. Spain had the highest daily per capita macromolecular antioxidant intake from fruit, while The Netherlands had the highest intake derived from vegetables. Future studies of plant food macromolecular antioxidant analysis and of dietary intakes in different populations are needed to elucidate the contribution of these macromolecular antioxidants to the health effects associated with fruit and vegetable consumption, and with dietary antioxidant intake. [ABSTRACT FROM AUTHOR]

• Evaluation of bioavailability of non-extractable polyphenols from cherry pomace. • Total phenolic and proanthocyanidin contents decrease in the digestion process. • The highest antioxidant capacity was obtained in the intestinal absorbed fraction. • Non-extractable polyphenols were identified in digestive and absorptive fractions. • Sweet cherry pomace presented bioavailable bioactive phenolic compounds. In vitro digestion and absorption simulation processes of non-extractable polyphenols (NEPs) obtained by pressurized liquid extraction combined with enzymatic-assisted extraction with Promod enzyme (PLE-EAE) from the residue of conventional extraction of sweet cherry pomace were studied. In general, total phenolic and proanthocyanidin contents decreased in each phase of the digestion. However, the antioxidant capacity increased when the digestion process progressed. In addition, the highest total phenolic and proanthocyanidin contents and antioxidant capacity were obtained in the absorbed fraction. NEPs from PLE-EAE extract, digestive fractions, absorbed and unabsorbed fractions were analyzed by ultra-high-performance liquid chromatography coupled to electrospray ionization quadrupole Exactive-Orbitrap mass spectrometry (UHPLC-ESI-Q-Orbitrap-MS). Fifteen NEPs were identified in the intestinal fraction and five in the absorbed fraction after the digestion process. Results obtained in this study define for the first time the bioavailability of antioxidant NEPs obtained from sweet cherry pomace. [ABSTRACT FROM AUTHOR]

Cereals are a major source of carbohydrates in diet occurring as soluble and insoluble non-starch polysaccharides, including dietary fibre. Dietary fibre plays an important role in the intestinal health and appears to be significantly associated with lower risk of developing coronary heart disease, stroke, hypertension, diabetes and obesity. They consist of a diverse group of molecules with varying degrees of water solubility, size and structure, which may influence the rheological properties of the gastrointestinal contents, flow of digesta and the digestion, absorption processes. Dietary antioxidants protect against oxidative damage to DNA, proteins, lipids and have a significant impact on the regulation of gene expression. The dietary antioxidants mainly polyphenolics, traverse the small intestine linked to dietary fibre. These antioxidants are released from the fibre matrix in the colon by the action of the bacterial microbiota, producing metabolites and an antioxidant environment. The present review focuses on the role of antioxidants linked to dietary fibre. [ABSTRACT FROM AUTHOR]

• Food function of dried persimmon and its fiber fraction was investigated. • The fiber fraction contained abundant non-extractable proanthocyanidins (NEPAs). • Fiber fraction rich in NEPAs showed a strong in vitro bile acid-binding ability. • Dried persimmon and the fiber fraction enhanced the bile acid-excretion in vivo. • Persimmons' NEPA content is essential for bile acid-binding and excretion. Dried persimmons contain abundant insoluble tannins comprised of non-extractable proanthocyanidins (NEPAs). To determine the beneficial function of NEPAs, we studied the bile acid-binding ability of NEPAs using in vitro and in vivo experiments. For the in vitro evaluation, 70% (v/v) acetone-insoluble solids (AIS) with different NEPA levels was prepared from persimmon fruits during drying. AIS with higher NEPA levels displayed stronger bile acid-binding activity, and the highest NEPA levels can be obtained from mostly-dried fruits. The in vivo bile acid-excreting effect of dried persimmon powder (DP) and AIS was verified by feeding experiments using C57BL/6J mice. The average bile acid-excretion was in order of low-fat group (1.07 µmol/day) < high-fat (HF) group (3.03 µmol/day) < HF + AIS group (4.44 µmol/day) < HF + DP group (6.74 µmol/day). These results suggest that the bile acid-excreting function of the fruit is related to the presence of NEPAs, which are constitutive ingredients of dried persimmon. [ABSTRACT FROM AUTHOR]

• Rapid fingerprinting of non-extractable polyphenols was carried out from tropical fruits peels. • Each hydrolysis treatment produced different phenolic profiles and signal intensities. • Enzymatic treatments were the most specific to extract non-extractable polyphenols. • Non-extractable polyphenols were identified in residues of all extractions. • Peels from tropical fruits showed a rich source of phenolic compounds. A simple and rapid direct analysis in real-time coupled to high-resolution mass spectrometry (DART-HRMS) methodology was developed to generate the extractable and non-extractable polyphenols (NEPs) fingerprint for four different passion fruits, G. mangostana , and A. squamosa peels as case-study to investigate the influence of alkaline hydrolysis and enzymatic-assisted extraction (EAE) on the recovery of NEPs. The extraction residue obtained after these treatments was also analyzed by DART-HRMS. Data compiled from DART-HRMS mass spectra were processed with principal component analysis to discriminate among the different treatments. EAE with Depol enzyme enabled to obtain NEPs with the highest signal intensity in DART-HRMS analysis from all peels except for P. edulis and A. squamosa peels. In these two cases, NEPs were better extracted by EAE with Promod enzyme and alkaline hydrolysis. Results showed that the applied treatments were efficient to extract NEPs since their signal intensities in the extraction residues were very low compared with their extracts. [ABSTRACT FROM AUTHOR]

Instant controlled pressure drop (DIC) is a technology able to modify the polyphenol profile in vegetal materials. However, information about how polyphenols are transformed, particularly regarding non-extractable polyphenol (NEPP), as well as the association with the initial content of polyphenols of the material is scarce. Thus, this work aimed to evaluate the DIC effect, modifying the pressure (0.2 and 0.4 MPa), the number of cycles (2 and 4), and grape pomace material (Malbec, Merlot, and Syrah) on extractable polyphenol (EPP) and NEPP contents. The EPP content increased during DIC application, an effect associated with the pressure, cycles, and initial polyphenol content. While for extractable and non-extractable proanthocyanidin contents, the main factors explaining the DIC effect are the pressure and number of cycles. Therefore, changes in polyphenols from grape pomace by DIC treatment are dependent upon experimental conditions, but the origin of the grape pomace also influences the extraction of EPP.

Sweet cherry generates large amounts of by-products within which pomace can be a source of bioactive phenolic compounds. Commonly, phenolic compounds have been obtained by conventional extraction methodologies. However, a significant fraction, called non-extractable polyphenols (NEPs), stays held in the conventional extraction residues. Therefore, in the present work, the release of NEPs from cherry pomace using pressurized liquid extraction (PLE) combined with enzyme-assisted extraction (EAE) using PromodTM enzyme is investigated for the first time. In order to study the influence of temperature, time, and pH on the NEPs extraction, a response surface methodology was carried out. PLE-EAE extracts displayed higher TPC (75 ± 8 mg GAE/100 g sample) as well as, PA content, and antioxidant capacity than the extracts obtained by PLE (with a TPC value of 14 ± 1 mg GAE/100 g sample) under the same extraction conditions, and those obtained by conventional methods (TPC of 8.30 ± 0.05 mg GAE/100 g sample). Thus, PLE-EAE treatment was more selective and sustainable to release NEPs from sweet cherry pomace compared with PLE without EAE treatment. Besides, size-exclusion chromatography profiles showed that PLE-EAE allowed obtaining NEPs with higher molecular weight (>8000 Da) than PLE alone. [ABSTRACT FROM AUTHOR]

• Development of extraction method for non-extractable polyphenols from cherry pomace. • Hydrolysis treatments recovered polyphenols from the extraction residue. • Enzymatic hydrolysis was efficient to extract non-extractable polyphenols. • Enzymatic extracts showed the highest antioxidant proanthocyanidin content. • Polyphenols with the highest molecular weight were observed in enzymatic extracts. Sweet cherries processing produces big amounts of wastes mainly constituted by cherry pomace that can be a source of bioactive polyphenols. However, during the extraction process, an important fraction called non-extractable polyphenols (NEPs) remains retained in the extraction residue. This work describes the development of an enzyme-assisted extraction (EAE) method to obtain NEPs from sweet cherry pomace employing three different enzymes. Box-Behnken experimental designs were employed to select the optimal conditions of extraction time, temperature, enzyme concentration, and pH. The total phenolic and proanthocyanidin contents and the antioxidant and antihypertensive capacities were measured. Optimal EAE conditions extracted higher content of proanthocyanidins and with higher bioactivity from extraction residue than alkaline and acid hydrolysis. Moreover, there were higher amounts of bioactive phenolics in the extraction residue than in the sweet cherry pomace extract. The estimation of NEPs molecular weight distribution by HPLC- SEC demonstrated that EAE extracted NEPs with high molecular weight. [ABSTRACT FROM AUTHOR]