Polymeric Pigments Research Articles

Study on the Effect of Graphene on Characteristics of Inorganic Polymer Paint

Study on the Effect of Graphene on Characteristics of Inorganic Polymer Paint

Characterization of colour, phenolics, and volatile compounds of 6 pomegranate varieties grown in Yunnan

Abstract Our study analysed the quality differences between 6 pomegranate varieties grown in Yunnan. The results showed that the composition and contents of anthocyanins, the amount of polymeric pigments produced by the reaction between anthocyanins and tannins, and pH were the primary factors affecting the colour of pomegranate arils. Fructose and citric acid were the main sugar and organic acid contributing to the taste of pomegranate arils. In total, 42 phenolic compounds were identified, with BS being classified as a distinct group due to higher concentrations of ACNs and flavonols. Additionally, 32 volatile compounds were identified, with TLZ, SP, and TGY grouped, BS, TNS, and HRY grouped into another. The key phenolic metabolic pathways included flavone and flavonol biosynthesis, anthocyanin biosynthesis, and phenylpropanoid biosynthesis, while fatty acid biosynthesis, pyruvate metabolism, and sulfur metabolism were the main volatile metabolic pathways. These results provide valuable guidance for agricultural practices and promoting industrial development.

Polysaccharide Functionality in Wine-like Model Systems with Oat and Egg White Model Proteins

Interactions between wine proteins and polysaccharides have the capacity to regulate the stability, shelf-life, and turbidity of red wines. Understanding these macromolecular interactions helps with maintaining stability and reproducing high quality wines. Model polysaccharides (carboxymethyl cellulose, mannoproteins, and fruit pectin) and model proteins (egg white and oat protein) were selected to assess protein–polysaccharide interactions within a model wine solution. The wine-like solution was created to simulate the correct pH, ethanol strength, and pigment content. Any interactions with polymeric pigments—anthocyanins and tannins—can also be investigated in this matrix. To analyze the aggregative potential of the macromolecules, particle size and Zeta-potential (ζ-potential) measurements were recorded for the samples with increasingly complex compositions. Carboxymethyl cellulose was found to increase particle sizes, likely binding more than proteins, but also improved the overall stability of the solution. Fruit pectin and mannoprotein were effective at causing precipitation while not removing the color of the model wine. The use of mannoprotein ensued in overall smaller particles for both suspended aggregate and precipitate sizes, indicating higher selectivity. Fruit pectin increased precipitate sizes and decreased suspended aggregate sizes. This study implements model proteins to evaluate complex macromolecular interactions using measurements of ζ-potential and particle size.

EVALUATION OF PHYSICAL AND MECHANICAL PROPERTIES OF THERMOPLASTIC COATING BASED ON POLYOLEFINS

The article presents an analysis of the results of physical and mechanical tests of thermoplastic coating samples after exposure to corrosive solutions. To obtain a thermoplastic coating, powder polymer paint of two original compositions was used. According to the results of the experiments conducted to study the change in the strength of the thermoplastic coating material based on polyolefins after its exposure to corrosive solutions, it is received that the decrease in the tensile strength is no more than 5 %. This is quite a good result, and is a background for their use on the metal surface of oil and gas equipment operating in corrosive mediums.

Additions/removals of seeds before fermentation alters Cabernet Sauvignon wine color via modulating anthocyanins and derivatives

The advance of the grape harvest caused by global warming has to some extent resulted in poor or unstable wine color, this study investigated the potential benefits of grape seeds on wine color to mitigate this negative effect. Anthocyanins and their derivatives, and chromatic characteristics were measured by targeted UHPLC-QqQ-MS/MS and CIELab methods, respectively. The addition of seeds was beneficial to the formation of polymeric pigments and flavanyl-pyranoanthocyanins, while decreased the accumulation of other yranoanthocyanins, monomeric anthocyanins, and acylated anthocyanins during fermentation. All pigment levels in seed wine can be better maintained over time. Compared with the removal of seeds during fermentation, the addition of seeds significantly enhanced the color intensity, bluish hues, and Chroma, while an appropriate amount of seeds favored wine red hue. PLSR showed that the addition/removal of seeds during fermentation could alter red wine chromatic characteristics via modulating anthocyanin profiles. These results can be used as reference to further explore the technological applications of seeds during fermentation for optimizing the potential benefits on red wine color.

The structural complexity of pyomelanin impacts UV shielding in Pseudomonas species with different lifestyles.

Pyomelanin, a polymeric pigment in Pseudomonas, arises mainly from alterations in tyrosine degradation. The chemical structure of pyomelanin remains elusive due to its heterogeneous nature. Here, we report strain-specific differences in pyomelanin structural features across Pseudomonas using PAO1 and PA14 reference strains carrying mutations in hmgA (a gene involved in pyomelanin synthesis), a melanogenic P. aeruginosa clinical isolate (PAM), and a melanogenic P. extremaustralis (PexM). UV spectra showed dual peaks for PAO1 and PA14 mutants and single peaks for PAM and PexM. FTIR phenol : alcohol ratio changes and complex NMR spectra indicated non-linear polymers. UVC radiation survival increased with pyomelanin addition, correlating with pigment absorption attenuation. P. extremaustralis UVC survival varied with melanin source, with PAO1 pyomelanin being the most protective. These findings delineate structure-based pyomelanin subgroups, having distinct physiological effects.

Bioinspired Three-Component System to Prepare Full-Color Functional Biomimetic Pigments.

Nature provides a great source of inspiration for the development of sustainable materials with excellent properties, among which melanin with optical, electronic, and radiation protection properties are considered to be promising coloring materials. However, compared to chemical pigments, the single color, complex oxidation process, and poor solubility of natural melanin strongly limit their further applications. Here, we introduce a series of melanin-like polymeric pigments with amino acid-encoded physicochemical properties by a simple three-component reaction system. Our protocol enables artificial control of the chromophore structures through the rational design of the substrates and dopants, thereby combining the safety and functionality of biopigments with the color richness of chemical dyes. Similar to the photoprotective effect of natural melanin, the polymeric pigments showed excellent antioxidant activity in reducing free radicals and have the advantages of iridescent color, strong tinting strength, stability, and affordability. Furthermore, due to their ability to dye substrates, these biomimetic are expected to become new low-cost bioactive chromophores and find various biochemical applications such as in clothing and hair dyeing, food addition, and anticounterfeiting detection.

Enhancing bioactive phenolic extraction from unfermented Cabernet Sauvignon pomace through tailored synergies of pH, proteolysis, and microwave processing

The impact of enzyme-assisted (EAE), microwave-assisted (MAE), and microwave enzyme-assisted (MEAE) extractions using water were evaluated and compared to aqueous (AEP), conventional ethanolic (CSE), and microwave ethanolic (MSE) controls for the release of phenolics from Cabernet Sauvignon grape pomace. Optimization of extract total phenolic content (TPC) involved stepwise screening of time, temperature, slurry pH, solids-to-liquid ratio, and enzyme conditions. The use of 0.1 % alkaline protease in MEAE (1:10 g pomace/mL water, pH 11.5, 70 °C, 30 min) reduced extraction time by 50 % compared to AEP, EAE, and CSE methods, doubling the TPC of the extracts to 100.9 mg GAE/g dry weight pomace compared to ethanolic extractions. MAE and MEAE extracts exhibited in vitro antioxidant activities (ABTS and ORAC) similar to ethanolic extracts and had greater antioxidant activities than AEP/EAE extracts while boosting relative contents of catechins, procyanidins, trans-piceid, and malvidin-3,5-diglucoside as detected by untargeted metabolomics. Quantitation by HPLC showed increased levels of gallic acid, protocatechuic acid, syringic acid, p-coumaric acid, polymeric phenols, and polymeric pigments in MEAE compared to hydroethanolic methods. Scanning electron microscopy further supported the synergistic role of microwave processing and proteolysis in disrupting the grape cell structure to aid in releasing valuable bioactive phenolic compounds.

Preparation of lanthanide aluminate‐encapsulated silica nanoparticles toward long‐persistent photoluminescent polymer paint with superhydrophobic and anticorrosion properties

AbstractSmart afterglow paints can function as energy‐saving products that are able to persist lighting in the dark. Additionally, polyurethane paints (PURPs) have shown some limitations, including weak adhesion, poor mechanical performance, poor corrosion, and low water resistance as compared with solvent‐based paints. Herein, nanoparticles of lanthanide aluminate (NLA; 16–24 nm) were mixed with polyurethane and silica to develop novel photoluminescent nanocomposite paints. A precursor of NLA‐encapsulated silica nanoparticles (NLA@Silica; 200–225 nm) can be described as a SiO2‐coated NLA pigment prepared by the heterogeneous precipitation method. Steel was coated with nanocomposite paints made of PURP, silica, and NLA. Using emission spectra and Commission Internationale de l'Eclairage (CIE) Lab coordinates, the coloring and transparency of painted films were investigated. Upon excitation at 365 nm, the UV‐irradiation of transparent painted films showed green emission at 518 nm. The hydrophobic activity and hardness properties were examined. Using electrochemical impedance spectroscopy (EIS), the anticorrosion of coatings applied to mild steel was studied. Improved anticorrosion characteristics were observed due to the fluorescence of NLA@Silica in the applied coatings. The optimal long‐lasting luminous characteristics were observed for nanocomposite films containing 12.5% of NLA@Silica.

Copper (II) Level in Musts Affects Acetaldehyde Concentration, Phenolic Composition, and Chromatic Characteristics of Red and White Wines.

Copper (II), a vital fungicide in organic viticulture, also acts as a wine oxidation catalyst. However, limited data are currently available on the impact that maximum allowed copper (II) ion doses in wine grapes at harvest can have on aged wine quality. This was the focus of the present study. We investigated the copper (II) effects by producing both white and red wines from musts containing three initial metal concentrations according to the limits set for organic farming. In detail, the influence of copper (II) on fermentation evolution, chromatic characteristics, and phenolic compounds was evaluated. Interestingly, the white wine obtained with the highest permitted copper (II) dose initially exceeded the concentration of 1.0 mg/L at fermentation completion. However, after one year of storage, the copper (II) content fell below 0.2 ± 0.01 mg/L. Conversely, red wines showed copper (II) levels below 1.0 mg/L at the end of fermentation, but the initial copper (II) level in musts significantly affected total native anthocyanins, color intensity, hue, and acetaldehyde concentration. After 12-month aging, significant differences were observed in polymeric pigments, thus suggesting a potential long-term effect of copper (II) on red wine color stability.

Effect of Cap Management Frequency on the Phenolic, Chromatic, and Sensory Composition of Cabernet Sauvignon Wines from the Central Coast of California over Two Vintages.

Cabernet Sauvignon from the California Paso Robles AVA was processed with a contrasting array of cap management frequencies, consisting of punch-down (PD) frequencies (0, 1, 2, and 3 PD/day) over two vintages, one of which the fruit was harvested at two contrasting maturity levels. Wines followed with up to 3 years of bottle aging for basic and phenolic chemistry, and the wines of the second harvest of 2020 were submitted to sensory analysis. There were almost non-existent effects due to the frequency of punch downs on parameters such as ethanol, pH, titratable acidity, lactic acid, and glucose + fructose. In 2019, the chromatic differences between different PD regimes were subtle, and minor effects of the punch-down frequency were observed for tannins and total phenolics. During the early stages of alcoholic fermentation, higher levels of all anthocyanin classes were observed in 1 PD wines and the lowest levels in 0 PD wines. The anthocyanin content of the wines of the first harvest (unripe) was 27% higher than that of the wines of the second harvest (ripe), but these differences disappeared after 3 years of bottle aging irrespective of the vintage and harvest date. Acylated anthocyanins were preferentially lost during aging, especially in 2019 wines and, to a lesser extent, in 2020 wines. In 2020, the polymeric pigment content of the wines of the second harvest was higher than in the wines of the first harvest, with 3 PD wines showing higher polymeric pigments and yellow hues than 0 and 2 PD wines after 3 years of bottle aging. Sensory analysis of the second harvest of the 2020 wines showed that the wines of all four PD regimes were perceived as drying, signifying they were perceived as equally astringent, which is consistent with comparable tannin levels on said wines. The perception of bitterness increased with the frequency of punch downs; thus, 3 PD wines showed the highest bitterness perception. It was concluded that in sufficiently warm fermentations and small volumes, phenolic extraction occurs regardless of fruit maturity and under conditions of minimum mixing.

Influence of Potential Alcohol in Grapes on Phenolic and Sensory Characteristics of Red Wine.

Potential alcohol, as obtained by grape maturity, affects the extraction of phenolics during winemaking. The extent to which potential alcohol is correlated to phenolic and sensory characteristics of red wine was investigated. Decoupling of the ripening kinetics of grape constituents due to climate change emphasizes this question. The impact of potential alcohol, as naturally obtained by grape maturity or adjusted by sugar addition, representing high sugar but low phenolic maturity, on wine characteristics was investigated for two varieties over two vintages. Enhancement of potential alcohol to late harvest conditions did not achieve the sensory characteristics of wine made from phenolic mature grapes. An experimental model was developed revealing the contribution of potential alcohol to phenolic and sensory characteristics. In Pinot noir, anthocyanins correlated well with natural potential alcohol but were not influenced by enhanced potential alcohol. In Cabernet Sauvignon, polymeric pigments provided the most accurate information about grape maturity perception in wine.

Pectin forms polymeric pigments by complexing anthocyanins during red winemaking and ageing

The long-term stability of red wine color depends on the formation of polymeric pigments from anthocyanins. Although there is still a lot of uncertainty about the specific structure of this diverse group of pigments, there is consensus that they are reaction products of anthocyanins and other polyphenols. Interactions between anthocyanins and pectic polysaccharides have been suggested to stabilize anthocyanins. This study explores the impact of such interactions by adding pectin during red winemaking.The results demonstrate that these interactions induce the formation of additional polymeric pigments which enhance the pigment stability during fermentation and aging. While initial pigment formation is higher in wines with added pectin, a notable proportion of the complexes degrades in the later stages of fermentation. Presumably, tannins form insoluble complexes with pectin, reducing tannin concentration by more than 300 mg/L. Anthocyanin concentrations decrease by over 400 mg/L, and polymeric pigments double.Anthocyanins that form polymeric pigments with pectic polysaccharides expand the range of pigments in red wines with possible consequences for the sensory properties of the wine. These findings highlight the complex interactions between pectin, anthocyanins, and tannins, and their influence on pigment formation and wine composition during fermentation and aging.

Extraction of tannin, colour and aroma compounds in pinot noir wines as affected by clone selection and whole bunch addition

Our previous study revealed stem inclusion fermentation reduced anthocyanin, and increased tannin and aroma compounds responsible for green notes. This study further investigated the effect of clone selection and whole bunch fermentation on Pinot noir wine composition, with focus on tannin composition. Three treatments were conducted using two clones (AM10/5 and UCD5) in 2021 and 2022: 100% destemmed (DS), 30% whole bunch (WB30), and 60% whole bunch (WB60). WB60 increased stem and skin derived tannins but reduced seed derived tannin proportion in wines. Clone selection had an impact on tannin composition and an even greater impact on tannin concentration, colour, and aroma compounds. AM10/5 produced wines with higher tannin, polymeric pigments and darker colour. AM10/5 wines also had higher concentration of phenylethyl alcohol, but lower concentrations of 3-isobutyl-2-methoxypyrazine and ethyl esters, indicating more floral but less fruity and green notes.

Comprehensive analysis of colloid formation, distribution, and properties of monovarietal red wines using asymmetrical flow field-flow fractionation with online multidetection

Red wine colloids, crucial in determining wine quality and stability, are understudied due to inadequate techniques for studying them effectively in the natural wine environment. Recently, Asymmetrical Flow Field-flow Fractionation (AF4) with online multidetection has emerged as a novel analytical tool for quantifying, fractionating, and characterizing red wine colloids in their native state. This study aimed to characterize the colloidal composition of 24 monovarietal Italian wines produced without filtration, oak contact, fining treatments, malolactic fermentation, macerating enzymes or ageing on yeast lees. AF4 analysis allowed quantification and characterization of wine colloids based on light scattering signal (MALS; gyration radius − Rg), size (hydrodynamic radius – Rh) and absorbance (A280 & A520 nm).The results showed that each wine contained up to five distinct colloids’ populations, varying in size and gyration radii. Despite possessing very similar Rh, most colloids exhibited great differences in compactness, as indicated by their varying Rg values. Comparing the A280 signal of whole wines to those of wines containing only species larger than 5 kDa (considered colloids) allowed to calculate the percentage of molecules involved in colloidal particles assembly, ranging from 1 to 44 % of the total A280 absorbing compounds, reflecting the diversity among wines. The A520 signal indicated the presence of polymeric pigments in the colloidal fraction. Notably, colored colloids all had Rg > 20 nm, indicating their association with other colloidal-forming compounds. This observation led to the conclusion that, apart from free anthocyanins and polymeric pigments, the color of red wines is also due to colloidal particles formed by the latter bound to proteins, with their quantity being highly variable across wines of different origin. These findings, which highlight the fundamental role of proteins in shaping the colloidal status of red wines, were utilized to propose an updated hypothetical model for colloidal aggregation in red wine.

Efficient isolation and characterization of functional melanin from various plant sources

SummaryIn recent years, natural pigments in living organisms have attracted increased interest as an excellent biological material for the development of new biotechnological approaches. Melanin, a large polymeric pigment, has important functions in cells, including free radical scavenging and radiation protection, making this molecule attractive for medical and nutritional purposes. The variety of forms of melanin in organisms requires the use of various approaches to its purification. In this study, we have developed a simple yet unique and effective method for extracting melanin from six plant sources. The melanin yield was in the range of 6.7–21.5% for the plant sources used. The advantage of using grape skin waste as a raw material is shown, which is of great importance for obtaining cheap and functional melanin. The activity of purified melanin in scavenging 2, 2‐diphenyl‐1‐picrylhydrazyl radical is IC50 3.2–99.0 mg L−1. This remarkable feature highlights the attractiveness of grape melanin for further use as a natural antioxidant in medicine. The ability of grape melanin to adsorb heavy metal ions highlights its attractiveness for the food industry and for the development of other biotechnological applications. Smoke, after passing through a cigarette filter charged with melanin, is significantly enriched with reducing agents, which is a phenomenon for the health of smokers.

Forecasting wine phenolic composition from infrared spectra of grapes extracts and monitoring of fermentations with optimised time-specific prediction models

Incorporating monitoring and forecasting technologies has the potential to enhance the different aspects of winemaking. By monitoring certain chemical parameters, it is possible to evaluate the progress of the fermentation and phenolic extraction, while also detecting deviations from expected behaviour. This study aims to investigate the development of a rapid forecasting method and different strategies to improve the accuracy of process monitoring. The first part involves the introduction of partial least squares (PLS) calibration models able to forecast the trajectories of phenolic extraction during fermentation using grape extract spectra. Additionally, novel methods for reoptimizing calibration models are proposed, with the intention of increasing the prediction accuracy. Whilst this method is transferable to PLS models, principal component regression (PCR) models were used instead as a more simplistic way to test the new methods. First, dynamic PCR linear regression coefficients were adapted over time to capture the compound evolution in the wine matrix. Secondly, PCR calibration models were reoptimized using interpolated spectral and reference data. The forecasting PLS calibration models have shown promising results for total anthocyanin content (mg/L), colour density, polymeric pigments (mg/L), MCP tannins (mg/L), and total phenolic index with overall R2 values on the validation set above 0.6, and low RSMEV values. Using interpolated data to re-optimise models was found to be more effective than global models or those using the calculated regression coefficients methods for predicting the concentration of a particular compound at a certain time point. While R2 values are suboptimal for all considered PCR models, in 72% of the cases analysed, the interpolation method for re-optimisation showed RMSEV values between 6% and 83% lower than those reported for a more traditional PCR model and other re-optimisation strategies. Interpolated models have shown consistency in predicting values, along with good performance metrics, indicating that they could be applied to samples for which calibration models do not exist.

Highly Stable Self-Cleaning Paints Based on Waste-Valorized PNC-Doped TiO2 Nanoparticles.

Adding photocatalytically active TiO2 nanoparticles (NPs) to polymeric paints is a feasible route toward self-cleaning coatings. While paint modification by TiO2-NPs may improve photoactivity, it may also cause polymer degradation and release of toxic volatile organic compounds. To counterbalance adverse effects, a synthesis method for nonmetal (P, N, and C)-doped TiO2-NPs is introduced, based purely on waste valorization. PNC-doped TiO2-NP characterization by vibrational and photoelectron spectroscopy, electron microscopy, diffraction, and thermal analysis suggests that TiO2-NPs were modified with phosphate (P=O), imine species (R=N-R), and carbon, which also hindered the anatase/rutile phase transformation, even upon 700 °C calcination. When added to water-based paints, PNC-doped TiO2-NPs achieved 96% removal of surface-adsorbed pollutants under natural sunlight or UV, paralleled by stability of the paint formulation, as confirmed by micro-Fourier transform infrared (FTIR) surface analysis. The origin of the photoinduced self-cleaning properties was rationalized by three-dimensional (3D) and synchronous photoluminescence spectroscopy, indicating that the dopants led to 7.3 times stronger inhibition of photoinduced e-/h+ recombination when compared to a benchmark P25 photocatalyst.

Streptomycetes as Microbial Cell Factories for the Biotechnological Production of Melanin.

Melanins are complex, polymeric pigments with interesting properties like UV-light absorbance ability, metal ion chelation capacity, antimicrobial action, redox behaviors, and scavenging properties. Based on these characteristics, melanins might be applied in different industrial fields like food packaging, environmental bioremediation, and bioelectronic fields. The actual melanin manufacturing process is not environmentally friendly as it is based on extraction and purification from cuttlefish. Synthetic melanin is available on the market, but it is more expensive than animal-sourced pigment and it requires long chemical procedures. The biotechnological production of microbial melanin, instead, might be a valid alternative. Streptomycetes synthesize melanins as pigments and as extracellular products. In this review, the melanin biotechnological production processes by different Streptomyces strains have been revised according to papers in the literature. The different fermentation strategies to increase melanin production such as the optimization of growth conditions and medium composition or the use of raw sources as growth substrates are here described. Diverse downstream purification processes are also reported as well as all the different analytical methods used to characterize the melanin produced by Streptomyces strains before its application in different fields.

Effects of Phenolic Evolution on Color Characteristics of Single-Cultivar Vitis vinifera L. Marselan and Merlot Wines during Vinification and Aging

The loss of red hue in dry red wine has been a persistent issue for wine enterprises in western China. We investigated the changes in anthocyanins and non-anthocyanin phenols during the industrial-scale fermentation and one-year bottle aging of Vitis vinifera L. Merlot and Vitis vinifera L. Marselan, respectively, using the grapes in the Ningxia region. We also examined their correlation with color characterization. The study found that both anthocyanins and non-anthocyanin phenolics were rapidly extracted from grapes during alcohol fermentation. However, their concentrations decreased rapidly during malolactic fermentation. On the other hand, Vitisin A and Vitisin B were formed during alcoholic fermentation and decreased slowly from malolactic fermentation to storage period. Directly polymerized pigments (F-A and A-F), bridged polymerized pigments (A-e-F), and flavanyl-pyranoanthocyanins (A-v-F) from the reactions of anthocyanins (A) and flavan-3-ols (F), as well as pinotins were generated during the later stages of alcoholic fermentation, and remained at a high level throughout malolactic fermentation and bottle storage. Partial least squares regression and Pearson correlation analyses revealed that the red hue (a* value) of ‘Merlot’ and ‘Marselan’ wines was closely associated with monomeric anthocyanins and F-A type pigments. Furthermore, four pinotin components were positively correlated with the red hue (a* value) of ‘Merlot’ wine. These primary red components of the two varieties had a positive correlation with the level of flavan-3-ols. The data suggest that elevating the flavan-3-ol concentration during fermentation aids in improving the color stability of red wine.