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3 pages, 170 KiB

Open AccessEditorial

Perspectives on Tannins

by Andrzej Szczurek

Biomolecules 2021, 11(3), 442; https://doi.org/10.3390/biom11030442 - 16 Mar 2021

Cited by 12 | Viewed by 3527

Abstract

Tannins are a family of versatile, natural phenolic biomolecules whose main role is to protect plants against insects and fungi [...] Full article

(This article belongs to the Special Issue Perspectives on Tannins)

Research

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11 pages, 984 KiB

Open AccessArticle

Mitigation of Ammonia Emissions from Cattle Manure Slurry by Tannins and Tannin-Based Polymers

by Thomas Sepperer, Gianluca Tondi, Alexander Petutschnigg, Timothy M. Young and Konrad Steiner

Biomolecules 2020, 10(4), 581; https://doi.org/10.3390/biom10040581 - 10 Apr 2020

Cited by 26 | Viewed by 6104

Abstract

With the extensive use of nitrogen-based fertilizer in agriculture, ammonia emissions, especially from cattle manure, are a serious environmental threat for soil and air. The European community committed to reduce the ammonia emissions by 30% by the year 2030 compared to 2005. After [...] Read more.

With the extensive use of nitrogen-based fertilizer in agriculture, ammonia emissions, especially from cattle manure, are a serious environmental threat for soil and air. The European community committed to reduce the ammonia emissions by 30% by the year 2030 compared to 2005. After a moderate initial reduction, the last report showed no further improvements in the last four years, keeping the 30% reduction a very challenging target for the next decade. In this study, the mitigation effect of different types of tannin and tannin-based adsorbent on the ammonia emission from manure was investigated. Firstly, we conducted a template study monitoring the ammonia emissions registered by addition of the tannin-based powders to a 0.1% ammonia solution and then we repeated the experiments with ready-to-spread farm-made manure slurry. The results showed that all tannin-based powders induced sensible reduction of pH and ammonia emitted. Reductions higher than 75% and 95% were registered for ammonia solution and cattle slurry, respectively, when using flavonoid-based powders. These findings are very promising considering that tannins and their derivatives will be extensively available due to the increasing interest on their exploitation for the synthesis of new-generation “green” materials. Full article

(This article belongs to the Special Issue Perspectives on Tannins)

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15 pages, 1473 KiB

Open AccessArticle

Optimization of Catechin and Proanthocyanidin Recovery from Grape Seeds Using Microwave-Assisted Extraction

by Jing Chen, W. P. D. Wass Thilakarathna, Tessema Astatkie and H. P. Vasantha Rupasinghe

Biomolecules 2020, 10(2), 243; https://doi.org/10.3390/biom10020243 - 5 Feb 2020

Cited by 32 | Viewed by 3973

Abstract

Grape seed extract (GSE) is a rich source of condensed flavonoid tannins, also called proanthocyanidins (PACs). The high molecular weight of polymeric PAC limits their biological activity due to poor bioavailability. The present study was undertaken to explore the potential applicability of microwave-assisted [...] Read more.

Grape seed extract (GSE) is a rich source of condensed flavonoid tannins, also called proanthocyanidins (PACs). The high molecular weight of polymeric PAC limits their biological activity due to poor bioavailability. The present study was undertaken to explore the potential applicability of microwave-assisted extraction (MAE) to convert GSE-PAC into monomeric catechins. A central composite design (CCD) was used to optimize the processing conditions for the MAE. The maximum total yield of monomeric catechins (catechin, epicatechin, and epicatechin gallate) and PAC were 8.2 mg/g dry weight (DW) and 56.4 mg catechin equivalence (CE)/g DW, respectively. The optimized MAE condition was 94% ethanol, 170 °C temperature, and a duration of 55 min. Compared to the results for PACs extracted via conventional extraction (Con) (94% ethanol; shaking at 25 °C for 55 min), MAE yielded 3.9-fold more monomeric catechins and 5.5-fold more PACs. The MAE showed higher antioxidant capacity and α-glucosidase inhibitory activity than that of the conventional extract, suggesting the potential use of the MAE products of grape seeds as a functional food ingredient and nutraceutical. Full article

(This article belongs to the Special Issue Perspectives on Tannins)

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12 pages, 6267 KiB

Open AccessArticle

Preliminary Studies on the Application of Grape Seed Extract in the Dyeing and Functional Modification of Cotton Fabric

by Ling Guo, Zhi-Yi Yang, Ren-Cheng Tang and Hua-Bin Yuan

Biomolecules 2020, 10(2), 220; https://doi.org/10.3390/biom10020220 - 2 Feb 2020

Cited by 22 | Viewed by 4125

Abstract

Cotton has the shortcomings of having no antibacterial, antioxidant and ultraviolet (UV) protection properties, which are of great importance for health protection purposes. In the present study, grape seed extract (GSE) mainly composed of proanthocyanins (tannins) was employed to simultaneously import pale colors [...] Read more.

Cotton has the shortcomings of having no antibacterial, antioxidant and ultraviolet (UV) protection properties, which are of great importance for health protection purposes. In the present study, grape seed extract (GSE) mainly composed of proanthocyanins (tannins) was employed to simultaneously import pale colors and the three aforementioned functions to cotton fabric. The tests on the application conditions of GSE showed that pH and GSE concentration had great impact on the color depth of cotton fabric, and the color hue of dyed fabric could be controlled in the absence of pH regulators due to the weakly acidic nature of GSE solution. The fabric dyed with 10%owf (on the weight of fabric) GSE exhibited an excellent inhibition effect towards Escherichia coli, whereas the one dyed with 20%owf GSE had high antioxidant activity of 97%. The fabric dyed with 5%owf GSE offered excellent UV protection. This study reveals that GSE can be used as a functional finishing agent for health protection in cotton textiles in addition to coloration capability. Full article

(This article belongs to the Special Issue Perspectives on Tannins)

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14 pages, 754 KiB

Open AccessArticle

The Effect of the Addition of Blue Honeysuckle Berry Juice to Apple Juice on the Selected Quality Characteristics, Anthocyanin Stability, and Antioxidant Properties

by Anna Grobelna, Stanisław Kalisz and Marek Kieliszek

Biomolecules 2019, 9(11), 744; https://doi.org/10.3390/biom9110744 - 17 Nov 2019

Cited by 79 | Viewed by 5296

Abstract

Apple juice is rich in phenolic compounds that are important as natural antioxidants. In turn, blue honeysuckle berry juice is a valuable source of bioactive ingredients and can be an interesting and beneficial supplement to fruit juices. The aim of this study was [...] Read more.

Apple juice is rich in phenolic compounds that are important as natural antioxidants. In turn, blue honeysuckle berry juice is a valuable source of bioactive ingredients and can be an interesting and beneficial supplement to fruit juices. The aim of this study was to examine the physicochemical and sensory properties of the newly designed mixture of apple juice and blue honeysuckle berry juice. The addition of blue honeysuckle berry juice to apple juice had a significant effect on the content of anthocyanin and vitamin C in the newly designed fruit juices. After production, the content of anthocyanins and polyphenols in the blue honeysuckle berry juice was high (595.39 and 767.88 mg/100 mL, respectively). As the concentration of blue honeysuckle berry juice added to apple juice was increased, the polyphenol content also increased. The juices analyzed after 4 months of storage were lighter and showed a less intense red color than the juices analyzed directly after production. Antioxidant activity (ABTS assay) in the apple juice mixed with 10% blueberry juice was almost 3 times higher than the pure apple juice after 3 months of storage; the addition of 30% blueberry juice significantly increased the antioxidant activity of the apple juice. Thus, the results of this research have expanded the existing knowledge about the health and sensory properties of apple juice mixed with blue honeysuckle berry juice. These findings can be utilized in further research aiming at the development of new products that can meet consumer expectations. Full article

(This article belongs to the Special Issue Perspectives on Tannins)

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14 pages, 2291 KiB

Open AccessArticle

Conformation and Aggregation of Human Serum Albumin in the Presence of Green Tea Polyphenol (EGCg) and/or Palmitic Acid

by Xiaowei Sun, Haley N. Ferguson and Ann E. Hagerman

Biomolecules 2019, 9(11), 705; https://doi.org/10.3390/biom9110705 - 5 Nov 2019

Cited by 16 | Viewed by 5858

Abstract

Polyphenols such as epigallocatechin gallate (EGCg) may have roles in preventing some chronic diseases when they are ingested as components of plant-based foods and beverages. Human serum albumin (HSA) is a multi-domain protein that binds various ligands and aids in their transport, distribution, [...] Read more.

Polyphenols such as epigallocatechin gallate (EGCg) may have roles in preventing some chronic diseases when they are ingested as components of plant-based foods and beverages. Human serum albumin (HSA) is a multi-domain protein that binds various ligands and aids in their transport, distribution, and metabolism in the circulatory system. In the present study, the HSA-EGCg interaction in the absence or presence of fatty acid has been investigated. Förster resonance energy transfer (FRET) was used to determine inter- and intra-domain distances in the protein with and without EGCg and palmitic acid (PA). By labeling Cys-34 with 7-(diethyl amino)-4-methylcoumarin 3-maleimide (CPM), the distance between Trp-214 at domain IIA and CPM-Cys-34 at domain IA could be established. A small amount of PA decreased the distance, while a large amount increased the distance up to 5.4 Å. EGCg increased the inter-domain distance in HSA and HSA-PA up to 2.8 and 7.6 Å, respectively. We concluded that PA affects protein conformation more significantly compared to EGCg. Circular dichroism (CD) established that EGCg affects protein secondary structure more significantly than PA. PA had little effect on the α-helix content of HSA, while EGCg decreased the α-helix content in a dose-dependent fashion. Moreover, EGCg decreased α-helix content in HSA and HSA-PA to the same level. Dynamic light scattering (DLS) data revealed that both PA and EGCg increased HSA aggregation. EGCg increased HSA aggregation more significantly and promoted formation of aggregates that were more heterogenous. Any of these effects could impact the ability of serum albumin to transport and stabilize ligands including EGCg and other polyphenols. Full article

(This article belongs to the Special Issue Perspectives on Tannins)

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Review

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34 pages, 4184 KiB

Open AccessReview

Tannin Gels and Their Carbon Derivatives: A Review

by Flavia Lega Braghiroli, Gisele Amaral-Labat, Alan Fernando Ney Boss, Clément Lacoste and Antonio Pizzi

Biomolecules 2019, 9(10), 587; https://doi.org/10.3390/biom9100587 - 8 Oct 2019

Cited by 39 | Viewed by 7058

Abstract

Tannins are one of the most natural, non-toxic, and highly reactive aromatic biomolecules classified as polyphenols. The reactive phenolic compounds present in their chemical structure can be an alternative precursor for the preparation of several polymeric materials for applications in distinct industries: adhesives [...] Read more.

Tannins are one of the most natural, non-toxic, and highly reactive aromatic biomolecules classified as polyphenols. The reactive phenolic compounds present in their chemical structure can be an alternative precursor for the preparation of several polymeric materials for applications in distinct industries: adhesives and coatings, leather tanning, wood protection, wine manufacture, animal feed industries, and recently also in the production of new porous materials (i.e., foams and gels). Among these new polymeric materials synthesized with tannins, organic and carbon gels have shown remarkable textural and physicochemical properties. Thus, this review presents and discusses the available studies on organic and carbon gels produced from tannin feedstock and how their properties are related to the different operating conditions, hence causing their cross-linking reaction mechanisms. Moreover, the steps during tannin gels preparation, such as the gelation and curing processes (under normal or hydrothermal conditions), solvent extraction, and gel drying approaches (i.e., supercritical, subcritical, and freeze-drying) as well as the methods available for their carbonization (i.e., pyrolysis and activation) are presented and discussed. Findings from organic and carbon tannin gels features demonstrate that their physicochemical and textural properties can vary greatly depending on the synthesis parameters, drying conditions, and carbonization methods. Research is still ongoing on the improvement of tannin gels synthesis and properties, but the review evaluates the application of these highly porous materials in multidisciplinary areas of science and engineering, including thermal insulation, contaminant sorption in drinking water and wastewater, and electrochemistry. Finally, the substitution of phenolic materials (i.e., phenol and resorcinol) by tannin in the production of gels could be beneficial to both the bioeconomy and the environment due to its low-cost, bio-based, non-toxic, and non-carcinogenic characteristics. Full article

(This article belongs to the Special Issue Perspectives on Tannins)

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30 pages, 5117 KiB

Open AccessEditor’s ChoiceReview

Tannins: Prospectives and Actual Industrial Applications

by Antonio Pizzi

Biomolecules 2019, 9(8), 344; https://doi.org/10.3390/biom9080344 - 5 Aug 2019

Cited by 201 | Viewed by 14207

Abstract

The origin of tannins, their historical evolution, their different types, and their applications are described. Old and established applications are described, as well as the future applications which are being developed at present and that promise to have an industrial impact in the [...] Read more.

The origin of tannins, their historical evolution, their different types, and their applications are described. Old and established applications are described, as well as the future applications which are being developed at present and that promise to have an industrial impact in the future. The chemistry of some of these applications is discussed where it is essential to understand the tannins and their derivates role. The essential points of each application, their drawbacks, and their chance of industrial application are briefly discussed. The article presents historical applications of tannins, such as leather, or traditional medicine, and more recent applications. Full article

(This article belongs to the Special Issue Perspectives on Tannins)

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