Antioxidants

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4 pages, 207 KiB

Open AccessEditorial

Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues

by Soraya Rodríguez-Rojo

Antioxidants 2021, 10(10), 1568; https://doi.org/10.3390/antiox10101568 - 1 Oct 2021

Cited by 2 | Viewed by 1511

Abstract

As is well known, there is an increasing interest in recovering phytochemicals from agricultural, forestry, and food industry residues, aiming to reduce their environmental impact and improve sustainable economic growth in the bioeconomy scheme [...] Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

Research

Jump to: Editorial, Review, Other

15 pages, 912 KiB

Open AccessArticle

Using High-Pressure Technology to Develop Antioxidant-Rich Extracts from Bravo de Esmolfe Apple Residues

by Mário Bordalo, Inês J. Seabra, Andreia Bento Silva, Ana Paula Terrasso, Catarina Brito, Margarida Serra, Maria R. Bronze, Catarina M. M. Duarte, Mara E. M. Braga, Hermínio C. de Sousa and Ana Teresa Serra

Antioxidants 2021, 10(9), 1469; https://doi.org/10.3390/antiox10091469 - 15 Sep 2021

Cited by 4 | Viewed by 2661

Abstract

Bravo de Esmolfe (BE) is a traditional Portuguese apple highly appreciated by consumers due to its peculiar flavor and aroma. This apple contains higher concentration of phenolic compounds than other cultivars and is thus considered a rich source of antioxidants. Its sensorial and [...] Read more.

Bravo de Esmolfe (BE) is a traditional Portuguese apple highly appreciated by consumers due to its peculiar flavor and aroma. This apple contains higher concentration of phenolic compounds than other cultivars and is thus considered a rich source of antioxidants. Its sensorial and functional properties have attracted farmers’ associations to increase BE production. However, a large quantity of apples is wasted due to storage/transportation procedures that impact BE’s quality attributes. In this work, we applied high-pressure extraction methodologies to generate antioxidant-rich fractions from BE residues aiming at adding high value to these agro-food by-products. We performed a first extraction step using supercritical CO₂, followed by a second extraction step where different CO₂ + ethanol mixtures (10–100% v/v) were tested. All experiments were carried out at 25 MPa and 50 °C. Extracts were characterized in terms of global yield, phenolic content and antioxidant activity using chemical (ORAC, HOSC, HORAC) and cell-based assays (CAA). We demonstrated that, although the pressurized 100% ethanol condition promoted the highest recovery of phenolic compounds (509 ± 8 mg GAE/100 g BE residues), the extract obtained with 40% ethanol presented the highest CAA (1.50 ± 0.24 µmol QE/g dw) and ORAC (285 ± 16 µmol TEAC/g dw), as well as HOSC and HORAC values, which correlated with its content of epicatechin and procyanidin B2. Noteworthy, this fraction inhibited free radical production in human neurospheroids derived from NT2 cells, a robust 3D cell model for neuroprotective testing. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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25 pages, 2175 KiB

Open AccessArticle

Olive Pomace Phenolic Compounds and Extracts Can Inhibit Inflammatory- and Oxidative-Related Diseases of Human Ocular Surface Epithelium

by Nikolaos Katsinas, Soraya Rodríguez-Rojo and Amalia Enríquez-de-Salamanca

Antioxidants 2021, 10(7), 1150; https://doi.org/10.3390/antiox10071150 - 20 Jul 2021

Cited by 19 | Viewed by 4100

Abstract

Oxidative- and inflammatory-related ocular surface diseases have high prevalence and are an emerging issue in ophthalmology. Olive pomace (OP) is the olive oil’s industry main by-product, and is potentially environmentally hazardous. Nevertheless, it contains phenolic compounds with important bioactivities, like oleuropein (OL) and [...] Read more.

Oxidative- and inflammatory-related ocular surface diseases have high prevalence and are an emerging issue in ophthalmology. Olive pomace (OP) is the olive oil’s industry main by-product, and is potentially environmentally hazardous. Nevertheless, it contains phenolic compounds with important bioactivities, like oleuropein (OL) and hydroxytyrosol (HT). The antioxidant and anti-inflammatory effects of four OP extracts (CONV, OPT(1–3)), pure OL and HT, and mixtures thereof were screened on human corneal (HCE) and conjunctival epithelial (IM-ConjEpi) cells. CONV was conventionally extracted, while OPT(1–3) were produced by pressurized liquid extraction. Thanks to their improved activity, CONV and OPT3 (HT-enriched) were selected for dose-dependent studies. Cells were stimulated with tumor necrosis factor-α or ultraviolet-B radiation, measuring interleukin (IL)-1β, IL-6, IL-8, and IL-17A as well as interferon γ-induced protein [IP]-10 secretion or intracellular ROS production, respectively. On HCE, both extracts and HT inhibited the secretion of most measured ILs, demonstrating a strong anti-inflammatory effect; while in IM-ConjEpi, all samples decreased IP-10 secretion. Moreover, HT, OL, and both extracts showed strong dose-dependent antioxidant activity in both cell lines. Compared with CONV, OPT3 was active at lower concentrations, demonstrating that intensified extraction techniques are selective towards targeted biomarkers. Hence, a high-value application as potential ocular surface therapy was proposed for the OP valorization. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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19 pages, 2018 KiB

Open AccessArticle

Microwave Pretreatment for the Extraction of Anthocyanins from Saffron Flowers: Assessment of Product Quality

by Ana Álvarez, Sara Terreros, María J. Cocero and Rafael B. Mato

Antioxidants 2021, 10(7), 1054; https://doi.org/10.3390/antiox10071054 - 29 Jun 2021

Cited by 13 | Viewed by 2471

Abstract

The potential of saffron flowers as a source of polyphenols, and in particular anthocyanins, for the extraction of bioactive compounds and the production of a cyanic colorant was analyzed. A microwave pretreatment, prior to the conventional solid–liquid extraction process, was proposed as a [...] Read more.

The potential of saffron flowers as a source of polyphenols, and in particular anthocyanins, for the extraction of bioactive compounds and the production of a cyanic colorant was analyzed. A microwave pretreatment, prior to the conventional solid–liquid extraction process, was proposed as a feasible intensification step. The effectiveness of microwave pretreatment was assessed in terms of increased yield and improved quality of the final product. The operational variables studied were the pretreatment temperature (60–120 °C) and the solid–liquid ratio (0.30–0.50 g/mL). It was found that the addition of the microwave pretreatment to the conventional process allowed one to reduce extraction time by up to 12 times and to greatly improve the characteristics of the final product, using microwave energy densities as low as 0.16–0.54 kJ/mL. The extract quality was evaluated in terms of polyphenol richness (25% increase), product composition (80% of the anthocyanins was delphinidin), antioxidant capacity (boosted by the pretreatment) and color (variations in red and blue hue depending on conditions). To conclude, a microwave pretreatment in which the material is heated to a temperature of 65 °C with a solvent ratio of 0.30 g/mL was selected as the optimum to maximize process efficiency and product quality. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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24 pages, 2763 KiB

Open AccessArticle

A Novel Strategy to Produce a Soluble and Bioactive Wheat Bran Ingredient Rich in Ferulic Acid

by Ana Belén Martín-Diana, Irene Tomé-Sánchez, María Jesús García-Casas, Cristina Martínez-Villaluenga, Juana Frías and Daniel Rico

Antioxidants 2021, 10(6), 969; https://doi.org/10.3390/antiox10060969 - 16 Jun 2021

Cited by 27 | Viewed by 3798

Abstract

Wheat bran (WB) is a byproduct from the milling industry that contains bioactive compounds beneficial to human health. The aim of this work was on the one hand, increasing extractability of antioxidant and anti-inflammatory compounds (specifically ferulic acid, FA), through enzymatic hydrolysis combined [...] Read more.

Wheat bran (WB) is a byproduct from the milling industry that contains bioactive compounds beneficial to human health. The aim of this work was on the one hand, increasing extractability of antioxidant and anti-inflammatory compounds (specifically ferulic acid, FA), through enzymatic hydrolysis combined with hydrothermal treatment (HT) and high hydrostatic pressure (HHP). On the other hand, enhancing the stability of final ingredient applying spray-drying (SPD) and microencapsulation (MEC). The use of HT increased FA, total phenolics (TP), and antioxidant capacity (AC) in WB hydrolysates, regardless the HT duration. However, the HT tested (30 min, HT30) produced a loss in anti-inflammatory activity (AIA). The combination of HT (15 min, HT15) with HHP increased AIA of the WB. SPD enhanced the TP yield in WB with no significant effect of inlet temperature (up to 140 °C) on phenolic profile mainly composed of trans-FA and smaller amounts of cis-FA and apigenin diglucosides. SPD caused a temperature-dependent increase in AC (160 °C > 140 °C > 130 °C). SPD inlet temperatures affected total solids yield (from 22 to 36%), with the highest values at 140 °C. The use of HHP in combination with HT resulted in >2-fold increase in total solids yield. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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18 pages, 1321 KiB

Open AccessArticle

Optimization of Glycerol–Water Extraction of Selected Bioactive Compounds from Peppermint and Common Nettle

by Grażyna Kowalska, Tomasz Baj, Radosław Kowalski and Jolanta Szymańska

Antioxidants 2021, 10(5), 817; https://doi.org/10.3390/antiox10050817 - 20 May 2021

Cited by 26 | Viewed by 4984

Abstract

Current trends in the industry indicate that extraction solvents should conform with the ideals of so-called “green chemistry”. Therefore, the objective of the presented study was to optimize the conditions for the extraction of polyphenols, flavonoids and chlorophyll from peppermint leaves (Mentha [...] Read more.

Current trends in the industry indicate that extraction solvents should conform with the ideals of so-called “green chemistry”. Therefore, the objective of the presented study was to optimize the conditions for the extraction of polyphenols, flavonoids and chlorophyll from peppermint leaves (Mentha × piperita L., Lamiaceae) and from common nettle leaves (Urtica dioica L., Urticaceae) via green chemistry. The obtained experimental results were subjected to modelling by means of the multiple regression method, while the optimization of the system was addressed via the application of the desirability function. As a result of the use of glycerol–water systems for the extraction of the tested active compounds from mint leaves and nettle leaves, extracts with higher concentrations of polyphenols, flavonoids and chlorophyll were most often obtained, when compared with the use of classical solvents such as water and ethanol. In this work, we demonstrate that the extraction temperature has significant influence on the concentration of the determined components in the extracts. To obtain the highest values of the analysed parameters, leaves of peppermint should be extracted with glycerol–water mixture at the proportions of 30.5:69.5 at a temperature of 50 °C, while the optimal conditions for the extraction of leaves of common nettle were the glycerol–water proportions of 12.5:87.5 and extraction temperature of 20 °C. Comparing the average percentage differences between the highest values of the analysed parameters obtained in the experiment and the approximated values for various temperatures with the level of desirability, one can note a high correlation that, in the analysed examples, amounted to 0.9681. The study showed that glycerol can be an alternative solvent in the extraction of polyphenols, flavonoids and chlorophyll, replacing, e.g., ethanol—which, for various reasons, cannot always be used. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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15 pages, 1763 KiB

Open AccessArticle

Valorization of Bilberry (Vaccinium myrtillus L.) Pomace by Enzyme-Assisted Extraction: Process Optimization and Comparison with Conventional Solid-Liquid Extraction

by Michail Syrpas, Egle Valanciene, Ernesta Augustiniene and Naglis Malys

Antioxidants 2021, 10(5), 773; https://doi.org/10.3390/antiox10050773 - 13 May 2021

Cited by 22 | Viewed by 3788

Abstract

Bilberry (Vaccinium myrtillus L.) pomace contains a significant amount of polyphenols and can serve as a basis for food additives, nutraceuticals, and functional foods. Although various techniques can be employed to recover bioactive fractions from berry pomaces, data on enzyme-assisted extraction (EAE) [...] Read more.

Bilberry (Vaccinium myrtillus L.) pomace contains a significant amount of polyphenols and can serve as a basis for food additives, nutraceuticals, and functional foods. Although various techniques can be employed to recover bioactive fractions from berry pomaces, data on enzyme-assisted extraction (EAE) of bilberry pomace are rather scarce. This study aimed to optimize critical EAE parameters using Viscozyme L to obtain a high-yield extract with enhanced antioxidant capacity. Central composite design and response surface methodology evaluating the effect of four independent variables, namely, pH, temperature, extraction time, and enzyme concentration on three responses, were employed to define optimal EAE conditions. Under the optimal conditions (pH: 4.5, temperature 46 °C, 1 h of extraction, and 2 active units (AU) of Viscozyme L/g of pomace), EAE yielded 56.15 g/100 g DW of the water-soluble fraction. Comparison with conventional maceration indicated that EAE, besides the yield, significantly increased the in vitro antioxidant capacity measured by the total phenolic content, ABTS, ORAC, and CUPRAC assays. Moreover, an increase was observed for the measured mono- and disaccharide as well as anthocyanin content. Overall, this study demonstrates the improved efficiency of EAE over conventional solid–liquid extraction to recover fractions with a higher yield and enhanced functional properties in a fast and sustainable manner. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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18 pages, 2049 KiB

Open AccessArticle

Enzyme-Assisted Extraction to Obtain Phenolic-Enriched Wine Lees with Enhanced Bioactivity in Hypertensive Rats

by Raúl López-Fernández-Sobrino, Maria Margalef, Cristina Torres-Fuentes, Javier Ávila-Román, Gerard Aragonès, Begoña Muguerza and Francisca Isabel Bravo

Antioxidants 2021, 10(4), 517; https://doi.org/10.3390/antiox10040517 - 26 Mar 2021

Cited by 21 | Viewed by 4251

Abstract

The antihypertensive effect of the soluble fraction of wine lees (WL) from Cabernet variety grapes was recently reported by our group. This blood pressure (BP)-lowering effect was attributed to the presence of flavanols and anthocyanins. In this context, phenolic-enriched wine lees (PWL) could [...] Read more.

The antihypertensive effect of the soluble fraction of wine lees (WL) from Cabernet variety grapes was recently reported by our group. This blood pressure (BP)-lowering effect was attributed to the presence of flavanols and anthocyanins. In this context, phenolic-enriched wine lees (PWL) could potentially exhibit a stronger bioactivity. Therefore, the aim of this study was to obtain a soluble fraction of WL with increased phenolic content and evaluate its functionality. The PWL were obtained using an enzyme-assisted extraction based on the hydrolysis of WL proteins with Flavourzyme^®. They contained 57.20% more total phenolic compounds than WL, with anthocyanins and flavanols being the largest families present. In addition, PWL also showed greater angiotensin-converting enzyme inhibitory and antioxidant activities. Finally, the antihypertensive activity of the PWL was evaluated in spontaneously hypertensive rats. A single dose of 5 mL/kg body weight of PWL showed a greater BP-lowering effect than the one shown by WL. Moreover, this antihypertensive effect was more prolonged than the one produced by the antihypertensive drug Captopril. These results demonstrate that enzymatic protein hydrolysis is a useful method to maximize the extraction of phenolic compounds from WL and to obtain extracts with enhanced functionalities. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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14 pages, 1079 KiB

Open AccessArticle

Chemical Properties of Vitis Vinifera Carménère Pomace Extracts Obtained by Hot Pressurized Liquid Extraction, and Their Inhibitory Effect on Type 2 Diabetes Mellitus Related Enzymes

by Nils Leander Huamán-Castilla, David Campos, Diego García-Ríos, Javier Parada, Maximiliano Martínez-Cifuentes, María Salomé Mariotti-Celis and José Ricardo Pérez-Correa

Antioxidants 2021, 10(3), 472; https://doi.org/10.3390/antiox10030472 - 17 Mar 2021

Cited by 24 | Viewed by 4219

Abstract

Grape pomace polyphenols inhibit Type 2 Diabetes Mellitus (T2DM)-related enzymes, reinforcing their sustainable recovery to be used as an alternative to the synthetic drug acarbose. Protic co-solvents (ethanol 15% and glycerol 15%) were evaluated in the hot pressurized liquid extraction (HPLE) of Carménère [...] Read more.

Grape pomace polyphenols inhibit Type 2 Diabetes Mellitus (T2DM)-related enzymes, reinforcing their sustainable recovery to be used as an alternative to the synthetic drug acarbose. Protic co-solvents (ethanol 15% and glycerol 15%) were evaluated in the hot pressurized liquid extraction (HPLE) of Carménère pomace at 90, 120, and 150 °C in order to obtain extracts rich in monomers and oligomers of procyanidins with high antioxidant capacities and inhibitory effects on α-amylase and α-glucosidase. The higher the HPLE temperature (from 90 °C to 150 °C) the higher the total polyphenol content (~79%, ~83%, and ~143% for water-ethanol, water-glycerol and pure water, respectively) and antioxidant capacity of the extracts (Oxygen Radical Absorbance Capacity, ORAC), increased by ~26%, 27% and 13%, while the half maximal inhibitory concentration (IC₅₀) decreased by ~65%, 67%, and 59% for water-ethanol, water-glycerol, and pure water extracts, respectively). Water-glycerol HPLE at 150 and 120 °C recovered the highest amounts of monomers (99, 421, and 112 µg/g dw of phenolic acids, flavanols, and flavonols, respectively) and dimers of procyanidins (65 and 87 µg/g dw of B1 and B2, respectively). At 90 °C, the water-ethanol mixture extracted the highest amounts of procyanidin trimers (13 and 49 µg/g dw of C1 and B2, respectively) and procyanidin tetramers of B2 di-O-gallate (13 µg/g dw). Among the Carménère pomace extracts analyzed in this study, 1000 µg/mL of the water-ethanol extract obtained, at 90 °C, reduced differentially the α-amylase (56%) and α-glucosidase (98%) activities. At the same concentration, acarbose inhibited 56% of α-amylase and 73% of α-glucosidase activities; thus, our grape HPLE extracts can be considered a good inhibitor compared to the synthetic drug. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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17 pages, 3377 KiB

Open AccessArticle

Old Plant, New Possibilities: Wild Bilberry (Vaccinium myrtillus L., Ericaceae) in Topical Skin Preparation

by Vanja M. Tadić, Ivana Nešić, Milica Martinović, Edward Rój, Snežana Brašanac-Vukanović, Svetolik Maksimović and Ana Žugić

Antioxidants 2021, 10(3), 465; https://doi.org/10.3390/antiox10030465 - 16 Mar 2021

Cited by 19 | Viewed by 4383

Abstract

Bilberry represents a valuable source of antioxidant substances responsible for its application for the treatment of different conditions (such as inflammation, cardiovascular disease, cancer, diabetes, and different age-related diseases) associated with increased oxidative stress. As oxidative stress might cause skin impairments, we aim [...] Read more.

Bilberry represents a valuable source of antioxidant substances responsible for its application for the treatment of different conditions (such as inflammation, cardiovascular disease, cancer, diabetes, and different age-related diseases) associated with increased oxidative stress. As oxidative stress might cause skin impairments, we aim to evaluate a topical preparation containing bilberry leaves extract and bilberry seeds oil, obtained as a byproduct of the food industry. To obtain the extracts, the conventional maceration technique for leaves, and supercritical carbon dioxide extraction for seeds were employed. The chemical profile of both actives was achieved by HPLC and GC methods, revealing the presence of phenolic acids (chlorogenic being the most abundant), flavonoids (isoquercetin in the highest amount), and resveratrol in leaves extract, while in seeds oil the essential ω-3 and ω-6 fatty acids were determined in favorable ratio, almost being 1. Antioxidant potential of the wild bilberry extract and seed oil was evaluated using in vitro DPPH and FRAP assays. Finally, effects of the oil-in-water creams with mentioned wild bilberry isolates on the skin were investigated in an in vivo study conducted on healthy human volunteers, revealing the significant beneficial effects when topically applied. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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15 pages, 5374 KiB

Open AccessArticle

Supercritical CO₂ Extraction and Microencapsulation of Lycopene-Enriched Oleoresins from Tomato Peels: Evidence on Antiproliferative and Cytocompatibility Activities

by Liliana Mihalcea, Oana Crăciunescu, Ionica Gheonea (Dima), Ana-Maria Prelipcean, Elena Enachi, Vasilica Barbu, Gabriela Elena Bahrim, Gabriela Râpeanu, Anca Oancea and Nicoleta Stănciuc

Antioxidants 2021, 10(2), 222; https://doi.org/10.3390/antiox10020222 - 2 Feb 2021

Cited by 11 | Viewed by 3038

Abstract

Tomato peels are used as a valuable material to extract lycopene-rich oleoresins by supercritical CO₂ extraction. The extraction involves continuous circling of CO₂ to the extractor after removing the solute in the separators, S40 and S45, where the solvent power of [...] Read more.

Tomato peels are used as a valuable material to extract lycopene-rich oleoresins by supercritical CO₂ extraction. The extraction involves continuous circling of CO₂ to the extractor after removing the solute in the separators, S40 and S45, where the solvent power of the CO₂ is reduced by reducing pressure down to 20 MPa in S40 and 5 MPa in S45, respectively, leading to two extracts. Lycopene is found to be the major compound, representing 93% and 76% of the total carotenoids in S40 and S45 extracts, respectively. The two extracts are microencapsulated in whey protein concentrate and acacia gum by complex coacervation and freeze-drying, leading to corresponding P40 and P45 powders, with antioxidant activity of 8.57 ± 0.74 and 9.37 ± 0.48 mMol TEAC/g DW in P40 and P45, respectively. Different structural and morphological patterns are observed, with finer microparticles of 1–2 µm in P45. Both powders show dose and time-dependent antiproliferative activity. The half-maximal inhibitory concentration values are 100 µg/mL for P40 and 750 µg/mL for P45 sample, indicating a higher antiproliferative effect of P40 over P45 in HT-29 cell culture. The powders have an extended range of cytocompatibility, up to 1000 µg/mL, in L929 normal cells, stimulating the cell growth. Lycopene retention is tested, and values of 48% and 29% in P40 and P45 are found after 21 days at 25 °C, with the degradation rate in P45 significantly higher, due to the higher content of the surface lycopene, which favored its degradation. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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13 pages, 554 KiB

Open AccessFeature PaperArticle

Optimization of Ultrasound-Assisted Extraction of Phloretin and Other Phenolic Compounds from Apple Tree Leaves (Malus domestica Borkh.) and Comparison of Different Cultivars from Estonia

by Sana Ben-Othman, Hedi Kaldmäe, Reelika Rätsep, Uko Bleive, Alar Aluvee and Toonika Rinken

Antioxidants 2021, 10(2), 189; https://doi.org/10.3390/antiox10020189 - 28 Jan 2021

Cited by 26 | Viewed by 3823

Abstract

Polyphenolic compounds, plant secondary metabolites essential for plant survival, are known for their high antioxidant and anti-inflammatory activity. In addition, several polyphenols, such as phloretin, also have potential antiviral effects, making these compounds potential ingredients of biofunctional foods. A promising source for the [...] Read more.

Polyphenolic compounds, plant secondary metabolites essential for plant survival, are known for their high antioxidant and anti-inflammatory activity. In addition, several polyphenols, such as phloretin, also have potential antiviral effects, making these compounds potential ingredients of biofunctional foods. A promising source for the extraction of phloretin is a by-product of apple production—apple tree leaves. Focusing on green technologies, the first aim of the present study was to optimize the direct ultrasound-assisted extraction conditions to gain the maximum yield of phloretin from air-dried apple leaves. For the optimization of process parameters, we applied the response surface method with Box–Behnken design. The optimal extraction conditions were extraction time 14.4 min, sonication amplitude 10% and 10 g of sample per 100 mL solvent (70% ethanol, w/w). Using these conditions, we assessed the content of individual and total polyphenolic compounds along with antioxidant activity in the leaves of different autumn and winter apple cultivars grown in Estonia. The analyses were carried out with chromatographic (HPLC-DAD-MS/MS) and spectrophotometric methods. The phloretin concentration ranged from 292 to 726 µg/g and antioxidant activity from 6.06 to 11.42 mg GA eq./g, these being the highest in the local winter cultivars ‘Paide taliõun’ and ‘Tellissaare’, respectively. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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18 pages, 1760 KiB

Open AccessArticle

Valorisation of Exhausted Olive Pomace by an Eco-Friendly Solvent Extraction Process of Natural Antioxidants

by Irene Gómez-Cruz, Cristóbal Cara, Inmaculada Romero, Eulogio Castro and Beatriz Gullón

Antioxidants 2020, 9(10), 1010; https://doi.org/10.3390/antiox9101010 - 17 Oct 2020

Cited by 43 | Viewed by 5999 | Correction

Abstract

Exhausted olive pomace (EOP) is the waste generated from the drying and subsequent extraction of residual oil from the olive pomace. In this work, the effect of different aqueous solvents on the recovery of antioxidant compounds from this lignocellulosic biomass was assessed. Water [...] Read more.

Exhausted olive pomace (EOP) is the waste generated from the drying and subsequent extraction of residual oil from the olive pomace. In this work, the effect of different aqueous solvents on the recovery of antioxidant compounds from this lignocellulosic biomass was assessed. Water extraction was selected as the best option for recovering bioactive compounds from EOP, and the influence of the main operational parameters involved in the extraction was evaluated by response surface methodology. Aqueous extraction of EOP under optimised conditions (10% solids, 85 ºC, and 90 min) yielded an extract with concentrations (per g EOP) of phenolic compounds and flavonoids of 44.5 mg gallic acid equivalent and 114.9 mg rutin equivalent, respectively. Hydroxytyrosol was identified as the major phenolic compound in EOP aqueous extracts. Moreover, these extracts showed high antioxidant activity, as well as moderate bactericidal action against some food-borne pathogens. In general, these results indicate the great potential of EOP as a source of bioactive compounds, with potential uses in several industrial applications. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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20 pages, 724 KiB

Open AccessArticle

Enzyme Selection and Hydrolysis under Optimal Conditions Improved Phenolic Acid Solubility, and Antioxidant and Anti-Inflammatory Activities of Wheat Bran

by Sara Bautista-Expósito, Irene Tomé-Sánchez, Ana Belén Martín-Diana, Juana Frias, Elena Peñas, Daniel Rico, María Jesús García Casas and Cristina Martínez-Villaluenga

Antioxidants 2020, 9(10), 984; https://doi.org/10.3390/antiox9100984 - 13 Oct 2020

Cited by 27 | Viewed by 4366

Abstract

Valorization of wheat bran (WB) into new high-value products is of great interest within the framework of sustainability and circular economy. In the present study, we utilized a multi-step approach to extract nutraceutical compounds (phenolic acids) from WB and improved its antioxidant and [...] Read more.

Valorization of wheat bran (WB) into new high-value products is of great interest within the framework of sustainability and circular economy. In the present study, we utilized a multi-step approach to extract nutraceutical compounds (phenolic acids) from WB and improved its antioxidant and anti-inflammatory properties through using sequential hydrothermal and enzymatic hydrolysis. Thirteen commercial glycosidases differing in their specific activity were screened and compared for hydrolytic efficiency to release monosaccharides, ferulic acid, and diferulic acid. Ultraflo XL was selected as the desired enzyme treatment on the basis of its higher WB solubilization, as well as its monosaccharide and phenolic acids yields. The relationships between better hydrolytic performance of Ultraflo XL and its particular activity profile were established. To determine the optimum conditions for Ultraflo XL treatment, we tested different factors (solvent pH, incubation temperature, and time) under 15 experiments. A multicomponent analysis (MCA), including central composite design, model fitness, regression coefficients, analysis of variance, 3D response curves, and desirability, was used for processing optimization. A beneficial effect of autoclave treatment on the release of phenolic compounds was also evidenced. The results of MCA showed involvement of linear, quadratic, and interactive effects of processing factors, although solvent pH was the main determinant factor, affecting enzymatic extraction of phenolics and bioactivity of hydrolysates. As compared to control WB, under optimized conditions (47 °C, pH = 4.4, and 20.8 h), WB hydrolysates showed 4.2, 1.5, 2, and 3 times higher content of ferulic acid (FA) and capacity to scavenge oxygen radicals, chelate transition metals, and inhibit monocyte chemoattractant protein-1 secretion in macrophages, respectively. These approaches could be applied for the sustainable utilization of WB, harnessing its nutraceutical potential. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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21 pages, 1688 KiB

Open AccessArticle

Effect of High Hydrostatic Pressure Extraction on Biological Activities and Phenolics Composition of Winter Savory Leaf Extracts

by Sílvia A. Moreira, Sara Silva, Eduardo Costa, Soraia Pinto, Bruno Sarmento, Jorge A. Saraiva and Manuela Pintado

Antioxidants 2020, 9(9), 841; https://doi.org/10.3390/antiox9090841 - 8 Sep 2020

Cited by 18 | Viewed by 3435

Abstract

Satureja montana L. has several biological properties related to its diverse composition of secondary metabolites. Nevertheless, it has been mainly studied for its essential oil, with only a few studies on the profile and bioactivities of the bioactive compounds from its leaf extracts [...] Read more.

Satureja montana L. has several biological properties related to its diverse composition of secondary metabolites. Nevertheless, it has been mainly studied for its essential oil, with only a few studies on the profile and bioactivities of the bioactive compounds from its leaf extracts being reported. This work aimed to study the antioxidant activity (by oxygen radical absorbance capacity (ORAC) assay), antimicrobial minimum inhibitory and bactericidal concentrations (MIC and MBC) determination, antibiofilm (by colorimetry), impact upon DNA (anti- and pro-oxidant assay), and cytotoxicity (by cell metabolism viability assays) of S. montana extracts obtained by high-pressure-assisted extraction (HPE). The extract obtained at 348 MPa, 35% (v/v) ethanol presented the highest concentration of individual phenolic compounds, and a minimum bactericidal concentration of 20 mg/mL against Listeria monocytogenes. HPE extracts showed antioxidant activity not only in ORAC but they were also able to prevent/attenuate peroxide-induced damage upon DNA. Moreover, on its own, HPE extract induced less oxidative damage than the control extract. Concerning the cytotoxicity, HPE extracts (at 0.5 and 1.0 mg/mL) were not harmful to HT29 cell lines, while control extracts (obtained at atmospheric pressure) at higher concentrations (>1.0 mg/mL) slightly reduced the metabolism of the cells. Finally, all extracts showed inhibition of the viability of 3 cancerous cell lines (>2.0 mg/mL for Caco-2, HeLa, and TR146) to below 15%. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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30 pages, 3986 KiB

Open AccessArticle

Batch and Flow Ultrasound-Assisted Extraction of Grape Stalks: Process Intensification Design up to a Multi-Kilo Scale

by Giorgio Grillo, Luisa Boffa, Salvatore Talarico, Roberto Solarino, Arianna Binello, Giuliano Cavaglià, Samir Bensaid, Galina Telysheva and Giancarlo Cravotto

Antioxidants 2020, 9(8), 730; https://doi.org/10.3390/antiox9080730 - 10 Aug 2020

Cited by 36 | Viewed by 3748

Abstract

Nowadays, approximately 1 billion kg/y of grape stalks, with a remarkable polyphenols content, are produced worldwide. In this paper, the extraction process intensification of polyphenols in water was achieved under ultrasound-assisted recovery, focusing on kinetics and scaling-up factors. Immersion and cup-horn systems were [...] Read more.

Nowadays, approximately 1 billion kg/y of grape stalks, with a remarkable polyphenols content, are produced worldwide. In this paper, the extraction process intensification of polyphenols in water was achieved under ultrasound-assisted recovery, focusing on kinetics and scaling-up factors. Immersion and cup-horn systems were exploited as acoustic cavitation sources, and the total phenolic content (TPC) was chosen to assess the process efficiency. The kinetics were evaluated by Peleg’s hyperbolic model, and the effect of both the initial feedstock granulometry and ultrasound size-reduction were determined. The results were compared with conventional extraction methods (data analysis by ANOVA). The best polyphenols yield was obtained after 45 min of sonication, giving between 29.71 and 31.89 mg/g (gallic acid equivalents over the dry matter). The extracts were characterized using HPLC-DAD, UPLC-ESI-MS/MS, DPPH^• assay (2,2-diphenyl-1-picrylhydrazyl), TEAC assay (Trolox equivalent antioxidant capacity), and proanthocyanidin content determination. The flow-mode extraction procedure of grape stalks (2 kg) was carried out in a 15 L reactor. A semi-industrial decanter unit and a bag-filter were the keys units of the downstream operations. The resulting particle-free solution underwent nanofiltration on a membrane pilot skid, providing a final polyphenols-enriched stream concentrated up to 355.91%, as shown by the antioxidant activity and TPC. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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11 pages, 658 KiB

Open AccessArticle

Phenylethyl Isothiocyanate Extracted from Watercress By-Products with Aqueous Micellar Systems: Development and Optimisation

by Ezequiel R. Coscueta, Celso A. Reis and Manuela Pintado

Antioxidants 2020, 9(8), 698; https://doi.org/10.3390/antiox9080698 - 3 Aug 2020

Cited by 25 | Viewed by 3937

Abstract

Phenylethyl isothiocyanate (PEITC) was reported as a useful antioxidant, anti-inflammatory, and chemopreventive agent. Due to technological and stability issues, it is necessary to be able to extract PEITC from its natural matrix (watercress) through sustainable and scalable methodologies. In this article, we explored, [...] Read more.

Phenylethyl isothiocyanate (PEITC) was reported as a useful antioxidant, anti-inflammatory, and chemopreventive agent. Due to technological and stability issues, it is necessary to be able to extract PEITC from its natural matrix (watercress) through sustainable and scalable methodologies. In this article, we explored, for the first time, the extractive capacity of aqueous micellar systems (AMSs) of two non-ionic surfactants. For this, we compared the AMSs with conventional organic solvents. Furthermore, we developed and optimised a new integral PEITC production and extraction process by a multifactorial experimental design. Finally, we analysed the antioxidant capacity by the oxygen radical absorbance capacity (ORAC) and ABTS methods. As results, the AMSs were able to extract PEITC at the same level as the tested conventional solvents. In addition, we optimised by response surface methodology the integrated process (2.0% m/m, 25.0 °C, pH 9.0), which was equally effective (ca. 2900 µg PEITC/g watercress), regardless of the surfactant used. The optimal extracts showed greater antioxidant capacity than pure PEITC, due to other antioxidant compounds extracted in the process. In conclusion, by the present work, we developed an innovative cost-effective and low environmental impact process for obtaining PEITC extracts from watercress by-products. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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24 pages, 5183 KiB

Open AccessReview

Extraction of Phenolic Compounds and Terpenes from Cannabis sativa L. By-Products: From Conventional to Intensified Processes

by Emilie Isidore, Hamza Karim and Irina Ioannou

Antioxidants 2021, 10(6), 942; https://doi.org/10.3390/antiox10060942 - 10 Jun 2021

Cited by 52 | Viewed by 11460

Abstract

Cannabis sativa L. is a controversial crop due to its high tetrahydrocannabinol content varieties; however, the hemp varieties get an increased interest. This paper describes (i) the main categories of phenolic compounds (flavonoids, stilbenoids and lignans) and terpenes (monoterpenes and sesquiterpenes) from C. [...] Read more.

Cannabis sativa L. is a controversial crop due to its high tetrahydrocannabinol content varieties; however, the hemp varieties get an increased interest. This paper describes (i) the main categories of phenolic compounds (flavonoids, stilbenoids and lignans) and terpenes (monoterpenes and sesquiterpenes) from C. sativa by-products and their biological activities and (ii) the main extraction techniques for their recovery. It includes not only common techniques such as conventional solvent extraction, and hydrodistillation, but also intensification and emerging techniques such as ultrasound-assisted extraction or supercritical CO₂ extraction. The effect of the operating conditions on the yield and composition of these categories of phenolic compounds and terpenes was discussed. A thorough investigation of innovative extraction techniques is indeed crucial for the extraction of phenolic compounds and terpenes from cannabis toward a sustainable industrial valorization of the whole plant. Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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2 pages, 773 KiB

Open AccessCorrection

Correction: Gómez-Cruz et al. Valorisation of Exhausted Olive Pomace by an Eco-Friendly Solvent Extraction Process of Natural Antioxidants. Antioxidants 2020, 9, 1010

by Irene Gómez-Cruz, Cristóbal Cara, Inmaculada Romero, Eulogio Castro and Beatriz Gullón

Antioxidants 2021, 10(6), 948; https://doi.org/10.3390/antiox10060948 - 11 Jun 2021

Cited by 1 | Viewed by 1869

Abstract

The author wishes to make the following correction to this paper [...] Full article

(This article belongs to the Special Issue Intensification Technologies to Efficiently Extract Antioxidants from Agro-Food Residues)

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