Polymeric Pigments Research Articles

The Effect of Micro-oxygenation on the Phenolic Composition, Quality and Aerobic Wine-Spoilage Microorganisms of Different South African Red Wines

The effect of micro-oxygenation treatments on the composition of different South African red wines was evaluated. In some wines, micro-oxygenation led to an increase in colour density, with a corresponding change in colour, due to the formation of polymeric pigments. This increase also led to the red colour becoming more resistant to the bleaching effect of SO2. Micro-oxygenation also seemed to be more effective in increasing the colour densities of younger red wines than the older ones, although total red pigments were found to be highest in an older red wine that had received micro-oxygenation. Differences in the gelatine index were also observed over time. The micro-oxygenated and barrel-matured wines also had lower concentrations of catechin and the procyanidin B1, and showed a corresponding increase in polymeric pigment and polymeric phenols. Micro-oxygenation led to higher acetic acid bacteria counts, although no increase in volatile acidity was observed in these wines. A tasting panel preferred younger red wines that had undergone micro-oxygenation. In an older red wine prolonged micro-oxygenation led to the wine becoming over-aged, with an increase in the barnyard/medicinal character, which corresponded with an increase in Brettanomyces counts. Micro-oxygenation can be used to increase the quality of young red wines, but further research is needed in this area.

Process development and monitoring in stripping of a highly transparent polymeric paint with ns-pulsed fiber laser

Laser paint removal was studied with ns-pulsed fiber laser on the combination of 20μm-thick, white polymeric paint and Al alloy substrate. The response of paint to single pulse ablation was evaluated to measure the ablated zone dimensions. With this information, the effect of overlap, number of passes and pulse repetition rate was evaluated to investigate machining depth. Optical emission spectroscopy was used to investigate the machining behaviour as well as to propose monitoring strategies. The results showed that despite the high transparency of the paint, complete paint removal can be achieved with reduced substrate damage (Sa=1.3μm). The emission spectroscopy can be used to identify removal completion as well as the reach of substrate material. The observations were also used to explain a paint removal mechanism based on thermal expansion of the paint and mechanical action provided by the plasma expansion from the substrate material.

Reaction Kinetics of Monomeric Anthocyanin Conversion to Polymeric Pigments and Their Significance to Color in Interspecific Hybrid Wines.

The color stability of red wines produced from interspecific hybrid grapes, which is partially dependent on anthocyanin diglucosides, is not well understood. In this study, the rate of decrease of monomeric anthocyanins as they polymerized to polymeric pigments due to the presence of excess catechin and acetaldehyde was measured in model wine using HPLC. Colorimetry was used to measure L*, a*, and b* values, hue angle, and change in color (ΔE). Concentrations of individual diglucosides decreased more slowly than monoglucosides. When monoglucosides and diglucosides were combined, the reaction rate of monoglucosides was slower than that of monoglucosides alone. Hue angles described transitions from red to red-orange, orange, or orange-yellow as anthocyanin-specific changes occurred. The evolution in color represents dynamic reactions between anthocyanins, catechin, and acetaldehyde. Consequently, wines containing high concentrations of diglucosides, such as those produced from interspecific hybrid grapes, will form less polymeric pigment than wines containing primarily monoglucosides.

Analysis of Melanin-like Pigment Synthesized from Homogentisic Acid, with or without Tyrosine, and Its Implications in Alkaptonuria.

Alkaptonuria is an iconic disease used by Archibald Garrod to demonstrate the theory of "inborn errors of metabolism". AKU knowledge has advanced in recent years: development of an in vitro model, discovery of murine models and advances in understanding bone and cartilage phenotypes and arthropathy in AKU. These discoveries have aided in a new clinical trial into nitisinone. However, there are still knowledge gaps surrounding the pigment in AKU and the pigmentation process. We demonstrate an advance in the understanding in the kinetics and chemistry of the polymerisation of homogentisic acid (HGA) into its pigment using size-exclusion chromatography and IR spectroscopy. We compared the properties of HGA-based pigments that were freshly prepared to those stored in solution for 2years. Our results demonstrate the importance of pH in the polymerisation process and that colour change seen in solution (analogous to AKU patient urine) is not initially due to presence of ochronotic pigment but the quinone intermediary. In addition, we observed that pigment formation from HGA can occur in the presence of tyrosine, without the inclusion of this tyrosine into the pigment. These observations have positive implications for patients with alkaptonuria; an increased understanding of the pigment polymer chemistry, the presence of an intermediary and their kinetics present more therapeutic opportunities for treating the condition, including preventing the pigment from forming, binding or reversing established pigmentation. AKU patients treated with nitisinone show elevated tyrosine levels causing side effects such as corneal opacities; our data demonstrates that elevated tyrosine levels should not contribute or add to the ochronotic pigment burden in these patients.

Characterisation of Colour Components and Polymeric Pigments of Commercial Red Wines by Using Selected UV-Vis Spectrophotometric Methods

The composition of the colour components of commercial red wines from Italy was analysed in terms of total colour, co-pigmentation, SO2-resistant pigments, small and large polymeric pigments, and tannins. A total of 128 wines, including Sangiovese, Cabernet Sauvignon, Nero d’Avola, Merlot, Marzemino, Negroamaro, Aglianico, Cannonau and Rossese di dolceacqua from five vintages (1999 to 2003) were analysed. The composition of the wines showed significant differences in terms of total colour and co-pigmentation. Total colour at 520 nm was highest in Marzemino (7.50±1.5 AU, absorbance units), and then in Aglianico (7.10±2.8 AU) and Cabernet Sauvignon (5.01±2.50 AU). The level of large and small polymeric pigments in Sangiovese wines showed a range from 0.05 to 0.40 and 0.10 to 0.27 AU 520 nm respectively. The variation in the level of polymeric pigments is affected by a number of factors, including vintage, grape composition, fermentation and storage conditions.

Characterisation of Pinotage Wine During Maturation on Different Oak Products

The effect of oak contact on the phenolic composition, total antioxidant capacity (TAC) and colour of Pinotage wines was investigated during maturation. Oak maturation included traditional treatments, such as new, second-fill and third-fill barrels, as well as alternative treatments (oak chips, staves, extract and dust) applied in old barrels over a period of 28 weeks. Oak maturation using traditional and alternative treatments improved the objective colour of Pinotage wine by decreasing the L* value. Losses in TAC caused by decreased concentrations of monomeric phenolic compounds (most anthocyanins, flavan-3-ols, flavonols and hydroxycinnamic acids) during oak maturation were negated by increased concentrations of gallic acid and the formation of new oligomeric and polymeric pigments. Wine maturation in stainless steel containers also resulted in a decrease in anthocyanin content. The decrease in phenolic acid content for wines matured in stainless steel was less pronounced, while their flavan-3-ol content remained stable. The new-barrel treatment had the most pronounced effect on all parameters. Oak maturation can be used for the production of Pinotage wine when the retention of TAC is a high priority.

Response of Grape and Wine Phenolic Composition in Vitis vinifera L. cv. Merlot to Variation in Grapevine Water Status

Grape and wine phenolic composition was monitored over two consecutive seasons in Vitis vinifera cv. Merlot following application of irrigation treatments that produced seasonal average stem water potentials ranging between -0.7 MPa and -1.4 MPa. Fresh weight of berries was significantly reduced in response to water deficit, primarily due to decreases in pericarp weight. Increases in the concentration of grape anthocyanins and flavonols in response to water deficit were found when expressed per unit grape berry fresh weight. Skin-derived tannin concentration in grape berries was not affected by the irrigation treatments. The concentration of grapederived phenolics was monitored during five days of fermentation in a small-lot winemaking experiment. During fermentation, the concentration of anthocyanins and flavonols in wine were highest in the non-irrigated and lowfrequency- irrigated treatments, which was reflected in changes in the wine colour of ferments. Finished wines from non-irrigated and low frequency irrigated grapevines showed increases in bisulphite-resistant pigments when compared with those irrigated at a high frequency, but differences in phenolic composition were minor. Increases in bisulphite-resistant pigments were associated with increases in vitisin A and polymeric pigment in the first and second seasons of the study respectively. Ageing of wines for an 18-month period increased bisulphite-resistant pigments, and treatment differences in wine colour density were enhanced, such that increases in both parameters were associated with the non-irrigated and low-frequency-irrigated treatments.

Evolution of pigments, tannins and acetaldehyde during forced oxidation of red wine: Effect of tannins addition

During wine-making and aging, the phenolic composition gradually changes, mainly owing to oxidation reactions, which may result in a decrease in astringency as well as in color stabilization. Anthocyanins and tannins are the main compounds involved in these changes. The influence of enological tannins on the outcome of red wine oxidation has been evaluated in this study. Oligomeric tannins were added to red wine so as to have wines with three different anthocyanin A/tannin T ratios W (ratio 1A: 0.5T) WT (ratio 1A: 1T) WTT (ratio 1A: 3T). Samples were then treated with hydrogen peroxide to trigger the Fenton reaction. Chromatic characteristics, phenolic composition and acetaldehyde were monitored during oxidation. The samples treated with a higher concentration of tannins showed a clear improvement of color intensity with oxidation mainly due to an increase in polymeric pigments. The higher the content of tannins were, the lower the production of acetaldehyde. These are the first data showing the effect of different A/T ratios on the production of acetaldehyde during an oxidation process.

Proteomic characterization of neuromelanin granules isolated from human substantia nigra by laser-microdissection.

Neuromelanin is a complex polymer pigment found primarily in the dopaminergic neurons of human substantia nigra. Neuromelanin pigment is stored in granules including a protein matrix and lipid droplets. Neuromelanin granules are yet only partially characterised regarding their structure and function. To clarify the exact function of neuromelanin granules in humans, their enrichment and in-depth characterization from human substantia nigra is necessary. Previously published global proteome studies of neuromelanin granules in human substantia nigra required high tissue amounts. Due to the limited availability of human brain tissue we established a new method based on laser microdissection combined with mass spectrometry for the isolation and analysis of neuromelanin granules. With this method it is possible for the first time to isolate a sufficient amount of neuromelanin granules for global proteomics analysis from ten 10 μm tissue sections. In total 1,000 proteins were identified associated with neuromelanin granules. More than 68% of those proteins were also identified in previously performed studies. Our results confirm and further extend previously described findings, supporting the connection of neuromelanin granules to iron homeostasis and lysosomes or endosomes. Hence, this method is suitable for the donor specific enrichment and proteomic analysis of neuromelanin granules.

Monitoring the Effect of Micro-oxygenation before Malolactic Fermentation on South African Pinotage Red Wine with Different Colour and Phenolic Analyses

The use of micro-oxygenation and its effect on the quality of the red wine varietal, Pinotage, is largely unknown. The influence of adding different oxygen dosages before malolactic fermentation on the phenolic composition and colour stabilisation of wine made from Pinotage was studied, and the suitability of certain spectrophotometric and RP-HPLC analyses to determine these changes were assessed in tanks of commercial lengths. Total oxygen dosages of 0 mg/L, 16 mg/L and 32 mg/L were applied, after which the wines underwent malolactic fermentation and maturation in the same tanks for two additional months. Decreases in anthocyanin concentration showed a strong inversely proportional correlation with increasing polymeric pigment concentration. This suggests that the addition of oxygen contributed to the early stabilisation of wine colour in Pinotage red wine. Overall, tannin concentrations were not significantly influenced by the oxygen treatments, although lower levels were observed in wines treated with oxygen. An important finding of the study was that there appeared to be little difference in the colour and phenolic composition of the wines between the 16 mg/L and 32 mg/L oxygen treatments. Good correlations were found between certain spectrophotometric techniques and the RP-HPLC analysis used to study changes induced by micro-oxygenation (total anthocyanins, total phenols). The colour and phenolic composition of Pinotage wine can be influenced before malolactic fermentation by micro-oxygenation. Some spectrophotometric phenolic analyses showed the same tendencies as observed with RP-HPLC (anthocyanins, monomeric flavan-3-ols, tannins), indicating their suitability to follow phenolic and colour changes induced by micro-oxygenation in Pinotage red wine.

Synthesis of opaque and colored hollow polymer pigments

A parametric study was carried out to investigate the effects of process parameters on the properties of opaque and/or colored polymer pigment. The core was synthesized using methyl methacrylate (MMA), methacrylic acid (MAA), and ethylene glycol dimethacrylate, and the shell from styrene. The surfactant/water (S/W) ratio was changed between 0.56 and 1.46, and the best ratio was determined to be 0.97. The increase in the amount of MAA and the pH of the medium increases the diameter of the swollen particles. The hollows could form only when the fraction of MAA in the monomer mixture was above 10%, and pH ≥ 10. The opaque pigment with the largest diameter could be obtained at the S/W ratio of 0.97 and the MAA content of 20%, as 350 nm. It gave an opacity value of 93.8% when mixed with an acrylic resin at 50% by volume. The colored opaque polymer pigments were synthesized by adding copper phthalocyanine into the monomer mixture. The addition of 2% copper phthalocyanine yielded a green-blue color but 3% yielded blue color. The latter yielded a change in the lightness (ΔL*) by a value of −31.49, and a total color difference (ΔE*) of 30.05 compared with that of white opaque polymer pigment. POLYM. ENG. SCI., 57:913–920, 2017. © 2016 Society of Plastics Engineers

Characterization of polymeric pigments and pyranoanthocyanins formed in microfermentations of non-Saccharomyces yeasts.

To assess the influence of non-Saccharomyces yeasts on the pyranoanthocyanins and polymeric pigments formation after the addition of (+)-catechin and procyanidin B2 to fresh red grape must. The fermentation of red grape musts was done with non-Saccharomyces yeasts either alone or in sequential fermentations with the Saccharomyces cerevisiae species. The characterization of both pyranoanthocyanin and polymeric pigments has been carried out with liquid chromatography coupled to mass spectroscopy (HPLC-DAD-ESI/MS). Red wines were also characterized by infrared spectroscopy (FTIR), gas chromatography (GC-FID) and spectrophotometry (UV-Vis). It has been observed that fermentation with the species Schizosaccharomyces pombe led to higher concentrations of pigments of all types: anthocyanins, polymeric pigments and pyranoanthocyanins, particularly vitisin A. The use of non-Saccharomyces yeasts improve the formation of stable pigments in red wines thanks to the differences in the microbial metabolism from among the yeasts studied. Colour stability as one of the main organoleptic properties in red wines, may be improved by the controlled use of selected non-Saccharomyces yeasts during red must fermentation.

Biosynthesis of catechol melanin from glycerol employing metabolically engineered Escherichia coli.

BackgroundMelanins comprise a chemically-diverse group of polymeric pigments whose function is related to protection against physical and chemical stress factors. These polymers have current and potential applications in the chemical, medical, electronics and materials industries. The biotechnological production of melanins offers the possibility of obtaining these pigments in pure form and relatively low cost. In this study, Escherichia coli strains were engineered to evaluate the production of melanin from supplemented catechol or from glycerol-derived catechol produced by an Escherichia coli strain generated by metabolic engineering.ResultsIt was determined that an improved mutant version of the tyrosinase from Rhizobium etli (MutmelA), could employ catechol as a substrate to generate melanin. Strain E. coli W3110 expressing MutmelA was grown in bioreactor batch cultures with catechol supplemented in the medium. Under these conditions, 0.29 g/L of catechol melanin were produced. A strain with the capacity to synthesize catechol melanin from a simple carbon source was generated by integrating the gene MutmelA into the chromosome of E. coli W3110 trpD9923, that has been modified to produce catechol by the expression of genes encoding a feedback inhibition resistant version of 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase, transketolase and anthranilate 1,2-dioxygenase from Pseudomonas aeruginosa PAO1. In batch cultures with this strain employing complex medium with 40 g/L glycerol as a carbon source, 1.21 g/L of catechol melanin were produced. The melanin was analysed by employing Fourier transform infrared spectroscopy, revealing the expected characteristics for a catechol-derived polymer.ConclusionsThis constitutes the first report of an engineered E. coli strain and a fermentation process for producing a catechol melanin from a simple carbon source (glycerol) at gram level, opening the possibility of generating a large quantity of this polymer for its detailed characterization and the development of novel applications.

Oxygen exposure of tannins-rich red wines during bottle aging. Influence on phenolics and color, astringency markers and sensory attributes

Three Southern Italy red wines Aglianico, Casavecchia and Pallagrello with high content of total tannins but different initial anthocyanins composition were aged in bottle for 15 months with closures allowing different degrees of wine oxygen exposure. In all wines oxygen exposure resulted in a progressive decrease in monomeric anthocyanins, vanillin reactive flavans and content of tannins reactive toward salivary proteins. In contrast, no significant decrease in color intensity was detected due to the formation of polymeric pigments. For all wines, the closure with the highest oxygen ingress determined a higher intensity of red fruit notes.

A review on Natural Dye: Gift from bacteria

Numerous pigments have been isolated from a variety of microorganisms including bacteria, fungi and protozoa. Bacterial pigments are water soluble or insoluble; water soluble pigments are diffused in the growth medium. Chemically, bacterial pigments are pyrrole, phenazine, carotenoid, xanthophylls and quinine or quinone derivatives. Structural information on many of these compounds like quinone which are amphiphilic in nature is an indicative of a strong membrane association potential. So as Food colorants may be classified into synthetic, nature-identical, inorganic, and natural colorants. Most often, the colorants are extracted from plant material, but other sources such as insects, algae, cyanobacteria, and fungi are used as well. A Halophylic bacterium has also been reported of producing different pigments. Synthesis of polymeric pigments is also been extensively studied now a days. The molecular genetic studies of pigment synthesis present vital scope for scaling up industrial importance of useful pigmented bacteria. The main objective of this study is to use pigments from locally isolated coloured bacteria as natural dyes to replace the existing synthetic dye.

CRONE control based anti-icing/deicing system for wind turbine blades

This paper presents an application of CRONE control, a robust control based on fractional order differentiation, to an anti-icing/deicing system for wind turbine blades. The deicing system uses an electrically conductive polymer paint applied on the blade at ice formation areas. The voltage applied to the paint leads to its heating. Based on a temperature measure provided by various sensors placed on the blade, a control system can thus be used to prevent the blade icing up during wind turbine operation or to deice the blade after a rest time. To design the control system, a thermal model of the blade with the paint was developed and its associated parameters were identified using tests in a climatic wind tunnel. A CRONE controller was then designed and its performance evaluated both on blade subparts in the climatic wind tunnel and on a floor-standing real blade.

Influence of copigmentation and phenolic composition on wine color.

Chromatic characteristics and their relationships with copigmentation and phenolic composition were studied in 160 bottled red wines. Free anthocyanins, copigmented anthocyanins and polymeric pigments contributing to color were calculated according to Boulton protocol and related to main changes produced in wine visible spectra after destroying any copigmented anthocyanins effect. Color differences between copigmented and non copigmented wines were quantified and related with ageing, cultivar and phenolic profile. Phenomenon of co-pigmentation visually increases the colour at 420, 520 and 620 nm for most of wines. Copigmented wines showed a mean value of 8.26 CIELab units higher than non copigmented (ΔEab(c-nc)), being this shift deeper for young wines than for aged wines. Copigmentation mostly changed hue and decreased L, a* and b* values therefore resulted into purplish and darker wine. Visual variations in color caused by copigmentation was related to particularly anthocyanins and copigments (mostly flavonols and hydroxycinnamic acids).

Synthesis and characterization of multi‐hollow opaque polymer pigments

ABSTRACTA new generation multihollow opaque polymer pigment was synthesized by suspension polymerization of “water‐in‐oil‐in‐water” emulsion method, where methyl methacrylate and ethylene glycol dimethacrylate monomer mixture was used as oil phase. The effects of surfactant and cosurfactant composition in terms of “hydrophilic/lipophilic balance” on the stability of the “water‐in‐oil” emulsion and the size of water droplets were studied. Low droplet sizes and the optimum stability were obtained with “Span 80&Tween 80” surfactant mixture at an HLB value of 8. The desired size distribution was obtained at “monomer/surfactant/water” ratio of 75.5/9.4/15.1 at an ultrasonic mixing power of 80 W lasting for 30 s. The surface morphology and hollow structure of polymer pigments were analyzed by scanning and transmission electron microscopy techniques. L*a*b color and gloss properties of polymer pigments were examined. The opacity values were assessed by contrast ratio measurements, and the pigments provided up to 97.3% opacity with 50% v/v solid content in resin. In addition, the pigments exhibited low gloss values and yielded matte films. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43696.

Effects of Vineyard and Winemaking Practices Impacting Berry Size on Evolution of Phenolics during Winemaking

Four methods of regulated deficit irrigation (RDI), an irrigation technique whereby water is supplied at rates at or below the full evapotranspiration (ETc), were applied to Cabernet Sauvignon grapes. The grapes were thereafter processed with three winemaking techniques: control (10-day maceration), extended maceration (EM; 30-day maceration), and saignee (removal of 16% of must by volume at crushing). The 25% ETc treatment had higher concentrations (fresh weight basis) of skin anthocyanins and seed tannins. Overall, skin tannins showed increased biosynthesis in 100% ETc and 25/100% ETc, whereas seed tannins were mostly (positively) affected due to a reduction of fresh weight in 25% ETc. Extraction of anthocyanins and tannins during winemaking ranged from 40 to 73% and from 17 to 26%, respectively. During maceration, the extraction curves for both anthocyanins and tannins were unaffected by the RDI treatments; quantitative differences were caused primarily by the winemaking treatments and secondarily by the RDI treatments. Consistent with a higher content of anthocyanins, 25% ETc wines had higher concentrations of polymeric pigments and greater color saturation and a* (red color component) both at day 30 and after 120 days post-crushing. EM enhanced seed tannin extraction, which resulted in a 50% increase in wine tannins relative to control and saignee wines, but it lowered anthocyanins and color saturation. Saignee increased anthocyanins at day 5 by 22% and tannins by 24% (relative to control wines), resulting in higher concentrations of polymeric pigments after 120 days. Both saignee and control wines had a roughly equivalent proportion of seed- and skin-derived tannins, whereas EM wines had 73% seed-derived tannins.

Impact ofPediococcusspp. on Pinot noir Wine Quality and Growth ofBrettanomyces

Pediococcus spp. were isolated from commercial wines from Oregon and Washington state, and the impacts of these isolates on the chemistry, microbiology, and sensory quality of Pinot noir wines were investigated. The pediococci isolates were inoculated into wines after alcoholic fermentation, and the wines were then chemically and sensorially analyzed after 60 days. All pediococci isolates partially degraded l-malic acid, with P. damnosus OW2 and P. parvulus OW7 completing malolactic fermentation (MLF). Despite having extensively large cell populations (>106 cfu/mL), the fermented wines had low concentrations of biogenic amines ( 5 mg/L). Production of d-lactic acid varied among the isolates, with strain OW7 producing the highest concentration (264 mg/L). Diacetyl concentrations also varied, with some wines containing low levels ( 15 mg/L). Furthermore, growth of some pediococci resulted in loss of red color and polymeric pigment content, potentially due to acetaldehyde degradation. Sensory analyses revealed differences in aroma (“floral”, “overall fruit”, “red fruit”, and “buttery”) and flavor (“sour” and “astringency”) among wines inoculated with different Pediococcus species or strains. Co-inoculation of P. parvulus and Brettanomyces bruxellensis resulted in wines having lower concentrations of 4-ethylphenol but reaching higher populations than in separate inoculations. This study has demonstrated the variability among Pediococcus species and strains in the production of various spoilage products and highlights the range of potential sensory effects these bacteria may have on a Pinot noir wine.