Copigmented Anthocyanins Research Articles

Stability of Copigmented Anthocyanins and Ascorbic Acid in Muscadine Grape Juice Processed by High Hydrostatic Pressure

Intermolecular copigmentation is one of the mechanisms of stabilization of anthocyanins in nature and is also responsible for the characteristic color and stability of aged red wines. In the present study, the effect of polyphenol oxidase (PPO) activity on phytochemical stability of an ascorbic acid-fortified muscadine grape juice following high hydrostatic pressure (HHP) processing (400 and 550 MPa for 15 min) and after 21 d of storage at 25 degrees C was investigated. Addition of rosemary and thyme polyphenolic extracts (copigmentation) was evaluated as a means to stabilize anthocyanins and ascorbic acid during pressurization and subsequent storage. Polyphenolic extracts were partially purified in order to reduce their content of PPO substrates, and improve their stabilization properties within juice matrix. Overall PPO activity increased (3- and 2.5-fold) following HHP at 400 and 550 MPa, respectively, although it was significantly lower in copigmented treatments. Higher anthocyanin losses occurred at 400 (approximately 70%) than at 550 MPa (approximately 46%), which were correlated to antioxidant losses (r = 0.89). Similarly, greater ascorbic acid losses were observed at 400 (84%) than at 550 MPa (18%). Copigmentation increased anthocyanin retention in reference to pressurized controls (3- and 3.2-fold for rosemary and thyme treatments, respectively) and decreased ascorbic degradation (20 to 32%). In stored samples, higher anthocyanin content (>2-fold) and antioxidant capacity (>1.5-fold) was observed for copigmented treatments when compared to control juices. Addition of partially purified copigments increased muscadine grape juice color, antioxidant activity and also reduced phytochemical losses during HHP processing and storage.

Interaction effects of nitrogen and potassium fertilization on anthocyanin composition and chromatic features of Tempranillo grapes

<p style="text-align: justify;">A factorial experiment (3 nitrogen and 3 potassium fertilization doses) was carried out in a Tempranillo vineyard located in the 'Ribera del Duero' Apellation d'Origine area (Spain) in 2000. N and K supplies caused decreases in delphinidin and petunidin monoglucoside content in grape skins. High nitrogen doses increase L* coordinate and chroma of the skins. High potassium with unbalanced nitrogen supplies enhances hue and yellow component of colour. Possible effects of N and K fertilization on the copigmentation of anthocyanins are discussed.</p>

The magnitude of copigmentation in the colour of aged red wines made in the Canary Islands

In order to study the magnitude of the copigmentation phenomenon in aged red wines, 84 samples of Listan negro wines were collected from several wineries in the Canary Islands. They were analysed at 1 and 2 years of age. The contribution of free anthocyanins, copigmented anthocyanins and polymeric pigments to the colour of wine, and the total phenols were determined. Moreover, coloured anthocyanins, total anthocyanins, percentage of total anthocyanins in coloured form and chemical age factor, and the chromatic characteristics of the wines were determined. The contribution to colour due to copigmented anthocyanins in these aged red wines remained at 22.3 and 18.5% (mean values) after 1 and 2 years of age, respectively, and the free anthocyanins at 37.0 and 32.5%. A comparison between the results obtained by Somers and Boulton methods has been established.

Caffeic acid copigmentation of anthocyanins from Cabernet Sauvignon grape extracts in model systems

Caffeic copigmentation of anthocyanins from Cabernet Sauvignon grape extracts in model system and yoghurt model system was investigated, as well as the influence of copigmentation on the stability of these pigments. In the model system, the dependence of anthocyanin stability on added caffeic acid was evaluated at temperatures (4 ± 1 °C and 29 ± 3 °C) and in the presence or absence of light, at two pH values: 3.0 and 4.0; in the yoghurt model system, the stability of the anthocyanins was evaluated at 4 ± 1 °C in the dark. The half-life and percentage of color retention of the anthocyanins in all treatments was calculated. The spectrophotometric results (Δ λ, Δ A) revealed that interaction occurred between the crude extract of anthocyanins and caffeic acid suggesting copigmentation. The addition of caffeic acid (1:1 w/v) significantly increased ( p < 0.05) the stability of anthocyanins in both model and yoghurt systems. In the model system the temperature and presence of light significantly influenced the stability of anthocyanins ( p < 0.05), where the highest values for half-life were obtained for anthocyanins with caffeic acid at pH 3.0, stored in the dark at a temperature of 4 ± 1 °C (6.930 h). In the yoghurt system the caffeic acid increased the half-life time of anthocyanins to 6673 h.

Charge-Transfer Complexation as a General Phenomenon in the Copigmentation of Anthocyanins

Color intensification of anthocyanin solutions in the presence of natural polyphenols (copigmentation) is re-interpreted in terms of charge transfer from the copigment to the anthocyanin. Flavylium cations are shown to be excellent electron acceptors (E(red) approximately -0.3 V vs SCE). It is also demonstrated, for a large series of anthocyanin-copigment pairs, that the standard Gibbs free energy of complex formation decreases linearly with EA(Anthoc) - IP(Cop), the difference between the electron affinity of the anthocyanin, EA(Anthoc), and the ionization potential of the copigment, IP(Cop). Based on this correlation, copigmentation strengths of potential candidates for copigments can be predicted.

Stability of Copigmented Anthocyanins and Ascorbic Acid in a Grape Juice Model System

The stability of red grape anthocyanins (Vitis vinifera) was evaluated in a model juice system during normal (25 degrees C) and accelerated storage (35 degrees C) in the presence of ascorbic acid. Rosemary polyphenolic cofactors (0, 0.2, and 0.4% v/v) were evaluated as anthocyanin stabilizing agents. Cofactor addition resulted in concentration-dependent hyperchromic (up to 178%) and bathochromic (up to 23 nm) shifts, indicating a more intense red coloration of the models. Anthocyanin and ascorbic acid degradation followed first-order kinetics during storage. Results showed that copigmented treatments underwent a lower conversion of L-ascorbic acid into dehydroascorbic acid during storage when compared to the control, favorably impacting the vitamin retention of these models. Copigmentation did not affect anthocyanin degradation in the absence of ascorbic acid but in its presence aided to retain a higher anthocyanin content than the control. This study indicated that the addition of anthocyanin cofactors could be used to reduce the pigment and vitamin degradation while masking detrimental color changes in anthocyanin containing products.

RELATIONSHIP BETWEEN ANTHOCYANIN PATTERNS AND ANTIOXIDANT CAPACITY IN MULBERRY WINE DURING STORAGE

ABSTRACT Mulberry wine stored for 1, 3, and 12 months was used to investigate the relationship between wine color, copigmentation, polymerization of anthocyanins, and the antioxidant capacity of the wine. Color density, patterns of anthocyanins (monomeric, copigmented and polymeric) and antioxidant capacity were measured. The results show that copigmented and polymeric anthocyanins in mulberry wine increased from 0% and 16.63% to 20.93% and 30.44%, respectively, while monomeric anthocyanins decreased from 83.37% to 48.63%. The 1,1,Diphenyl‐2‐picryl‐hydrazyl (DPPH) radical scavenging ability increased after storage and was highly correlated with the polymeric anthocyanin content (r = 0.98). The ferric reducing ability of plasma (FRAP) reducing power decreased on storage. Sephadex G25 was used to separate the pigments into three different molecular sizes. The largest molecules were in Fraction I, which contained the polymerized anthocyanins and was associated with the DPPH scavenging activity. Fraction II, intermediate in size, contained the copigmented anthocyanins. Fraction III, the smallest in size, was composed of the monomeric anthocyanins and was associated with the FRAP activity.

Phenolic composition and magnitude of copigmentation in young and shortly aged red wines made from the cultivars, Cabernet Sauvignon, Cencibel, and Syrah

Young and shortly aged red wines made from single cultivar grapes grown in the warm climate region of La Mancha (Spain), were examined for their phenolic composition and effects of copigmentation on wine colour. In addition to anthocyanins, flavonol and hydroxycinnamic acid profiles allowed the varietal differentiation of these wines. Characteristic flavonols found were principally glycosides, the main ones, being: myricetin 3-glucoside, quercetin 3-glucoside, and quercetin 3-glucuronide. The fraction of red colour due to copigmented anthocyanins ranged from 32% to 43% at the end of the alcoholic fermentation, and this decreased to 20–34% after 3 months of ageing, when a decrease in both monomeric anthocyanin and flavonol concentrations was also observed . Cencibel wines showed the greatest loss in flavonols after 3 months, but these were apparently replaced, in the copigmentation complexes, by other abundant cofactors, such as hydroxycinnamic acids and (−)-epicatechin. Thereafter, Cencibel wines showed proportionally the lowest decrease in this copigmentation effect at this ageing time. After 9 months, the losses of monomeric anthocyanins and cofactors still continued, and only Syrah wines showed a little enhancement of the red colour intensity. At this ageing time, the amounts of monomeric anthocyanins were sufficient for the formation of copigmentation complexes, but the molar ratio of cofactors to anthocyanins was possibly too low for detecting significant effects on colour, especially in Cabernet Sauvignon and Cencibel wines. A second observed effect of copigmentation was the bathochromic shift to bluish hues for Cencibel and Syrah wines, and it only was maintained in the latter wine during all the ageing times checked.

Effect of polymerization on the antioxidant capacity of anthocyanins in Roselle

The aim of this study is to investigate how antioxidant capacity [1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging effect, ferric reducing ability of plasma (FRAP) and Trolox equivalent antioxidant capacity (TEAC)] changes during anthocyanin degradation and brown pigment formation. Roselle anthocyanin model system was used to compare changes of three patterns of anthocaynin (monomeric, co-pigmented and polymeric), colour density and degradation index (DI). After heating, Roselle anthocyanins were separated into three fractions by gel filtration to elucidate the contribution of each fraction to the antioxidant capacity. In the model system, colour density, FRAP activity, monomeric and co-pigmented anthocyanins decreased after heating, while DI, polymeric anthocyanins, and DPPH scavenging effect increased after heating. Statistical analysis showed polymeric or monomeric anthocyanins were positively related to DPPH scavenging effect or FRAP activity with respective coefficients of 0.97 and 0.84. Further purification using Sephadex G25 separate the pigment into three fractions, I, II and III, according to their decreasing molecular size. Results indicated that the contribution percentage of DPPH scavenging effect of fraction II increased after being heated, while the contribution in FRAP activity of fraction III dropped. This suggested that fractions II and III might be the major contributors for DPPH scavenging ability and FRAP activity, respectively.

Thermal stability of Hibiscus sabdariffa L. anthocyanins in solution and in solid state: effects of copigmentation and glass transition

Kinetic studies on thermal stability of anthocyanins isolated from the dry calyces of Hibiscus sabdariffa L. (roselle) were carried out in aqueous solutions (55–98 °C), either as free or copigmented anthocyanins with chlorogenic acid, and in the dry state as free anthocyanins or co-lyophilized with an amorphous polysaccharide (pullulan) and stored in different relative humidity environments (water activities 0.33, 0.53, 0.75 and 0.84) at 40 °C. The rate constants for degradation were obtained from first-order reaction kinetic plots. The degradation kinetics of individual anthocyanin components in solution, as assessed by HPLC, followed an Arrhenius-type response with respect to temperature; activation energies, E a, varied between 13.3 and 15.1 kcal/mol. Copigmentation of anthocyanins with chlorogenic acid did not seem to improve their stability in solution. In the dry state, the degradation rate constants increased with the water activity, particularly above 0.53. In the freeze-dried pullulan–anthocyanin mixtures, the polysaccharide matrix delayed colour degradation compared to the free anthocyanin preparations by 1.5–1.8 times. The degradation kinetics of anthocyanins did not show any dependence on the molecular mobility of the system, as it relates to the glass–rubber transition ( T g) detectable by calorimetry. Anthocyanin degradation occurred, even at sub- T g temperatures of the amorphous matrices, whereas no changes in the rate constants were observed in the vicinity of the glass transition; the plot of (ln k) −1 against ( T− T g) was linear with all data fitting into a common line as predicted by the Williams–Landel–Ferry (WLF) equation. Both free and co-lyophilized with pullulan Hibiscus anthocyanins exhibited good antiradical activity throughout storage in all humidity environments studied, despite of a substantial loss in colour intensity.

Phytochemical Stability and Color Retention of Copigmented and Processed Muscadine Grape Juice

Muscadine (Vitis rotundifolia) grape juice was assessed for color and phytochemical stability as influenced by anthocyanin copigmentation with a water-soluble rosemary extract, fortification with ascorbic acid, and processing by heat or high hydrostatic pressure (HHP). The roles of polyphenolic cofactors in the presence and in the absence of ascorbic acid were assessed as a means to improve the overall processing stability of the juice. Addition of rosemary extract from 0 to 0.4% (v/v) readily formed copigment complexes with anthocyanins and resulted in concentration-dependent hyperchromic shifts from 10 to 27% that corresponded to increased antioxidant activity. The presence of ascorbic acid was generally detrimental to juice quality, especially in the presence of rosemary extract, and resulted in overall anthocyanin, ascorbic acid, and antioxidant activity losses. Although thermal and high-pressure processing methods were detrimental to juice quality, HHP resulted in greater losses after processing, likely due to action from residual oxidase enzymes. Although physicochemical attributes were enhanced by copigmentation with rosemary extract, methods to inactivate residual enzymes should be addressed prior to copigmentation to prevent degradation of anthocyanins in the presence of ascorbic acid.

Development of predictive models for astringency from anthocyanin, phenolic and color analyses of British Columbia red wines

&lt;p style="text-align: justify;"&gt;One-hundred and eighty-nine commercial red wines from four vintages (1996-1999), four varieties (Pinot noir, Merlot, Cabernet franc, Cabernet Sauvignon) and 13 vineyard locations within the Okanagan Valley of British Columbia were analysed for total phenolics, anthocyanins, flavonols, tartaric esters, free SO&lt;sub&gt;2&lt;/sub&gt;, pH and titratable acidity, as well as copigmented-, monomeric-, polymeric- and total- anthocyanins (absorbance values). Color was evaluated using color density, hue, Hunter-color (L, a, b) and chroma values. Statistics (means, standard deviations) and discriminant analysis were used to explore the response patterns in the compositional analyses among the vintages, varieties and vineyard locations. Color density was highly correlated to the monomeric- and polymeric- anthocyanins for all varieties. Discriminant analysis revealed that some wine vintages could be differentiated using the flavonols, anthocyanins, copigmented anthocyanins, hue and L values. Phenolic concentrations were lower in 1996 and 1997 vintages compared to 1998 and 1999. Discriminant analysis showed that the varieties Pinot noir, Cabernet franc and Merlot/Cabernet Sauvignon could be differentiated using the monomeric-, polymeric- and total- anthocyanins, as well as color density, hue and L values. Cabernet Sauvignon wines formed a subset within the Merlot grouping. Discriminant of wines from the vineyard locations revealed that there was a considerable overlap among the regions, but that the groupings were generally consistent with geographic location. Sensory analysis was used to determine the intensity of astringency and astringent aftertaste in a subset of 35 wines from 1998. Multiple linear regression was used to relate the sensory and compositional analyses. A two-variable model predicted astringency (R=0.77) from total phenolics and copigmented anthocyanins; whereas, a one-variable model was developed to predict astringent aftertaste (R=0.74) from total phenolics. Sensory data collected on an additional 25 red wines were used to validate the appropriateness of the models.&lt;/p&gt;

Colour effects of co-pigmentation of anthocyanin revisited—3. A further description using CIELAB differences and assessment of matched colours using the CMC model

Abstract Extensive colour difference calculations (CIELAB and CMC models for CIE D 65 /10°, Ill./Obs.) were applied to the colorimetric coordinates previously gathered on 224 pure or co-pigmented (by rutin) solutions of cyanin at pH between 2.5 and 5.5. CIELAB coordinates additionally recorded on acidic (0.1N HCl) methanolic and aqueous cyanin solutions (10 −5 M−2.5×10 −3 M) showed the considerable hue gamut covered by each series of solutions (1/6 and 1/8 of the colour circle). A markedly yellowing effect of water vs. methanol was observable and it represented the most influential parameter in the impressive CIELAB differences (Δ E * up to 38 units) caused by the solvent. On aqueous cyanin solutions, successive one unit pH elevations resulted in huge colour gaps (up to Δ E * > 60 units, at pH 3.5 vs. 2.5). The corresponding ‘loss of colour’ was mainly attributable to a decreasing chroma (Δ C *) while the coupled hue differences (Δ H *) corresponded to more or less deep blueing effects at pH elevations up to 4.5 and more unexpectedly to yellowing effects at pH increased to 5.5. Using CMC difference calculations, the colours of 0.1 N HCl aqueous solutions at low concentrations were best matched by those of cyanin solutions at pH 2.5 and about 2–2.5 fold higher concentrations; at high concentrations, their colours were preferentially simulated by solutions at each corresponding—or lower—cyanin concentration but co-pigmented by rutin (up to 4:1 ratio). Similar, but more complex features, emerged in the constitution of many best matched couples of colours from the database of model solutions at pHs 2.5–5.5. Close—or even identical—colour stimuli were also shown to be based on either closely matched or quite distinctly shaped spectral curves. The complete ‘colour by numbers’ approach presented in this series of papers may find applications in many fields in which anthocyanic pigments are employed, as natural food colorants for instance.

Influence of trans-cis isomerisation of coumaric acid substituents on colour variance and stabilisation in anthocyanins

The recently isolated pigments from Petunia integrifolia and Triteleia bridgesii present a distinct feature that sheds new light on the understanding of intramolecular copigmentation of anthocyanins. These are among the infrequent anthocyanins that naturally present a coumaric acid substituent in both cis and trans forms. As a consequence, the two isomers demonstrate substantial variations of their thermodynamic and kinetic constants and also colour properties. A possible explanation for these characteristics is presented, making use of molecular modelling and taking into account the three-dimensional structures of the pigments.

Quercetin (=2-(3,4-Dihydroxyphenyl)-3,5,7-trihydroxy-4H-1- benzopyran-4-one) Glycosides and Sulfates: Chemical Synthesis, Complexation, and Antioxidant Properties

Glycosides, acylated glycosides, and sulfates of quercetin (=3,3′,4′,5,7-pentahydroxyflavone; 1), which is, together with its derivatives, among the most common polyphenols found in plants and in the human diet, were prepared and quantitatively investigated for their ability to bind metal ions (AlIII, FeII, FeIII), enhance and vary natural colours (anthocyanin copigmentation), and trap potentially damaging radicals (antioxidant activity).

The Copigmentation of Anthocyanins and Its Role in the Color of Red Wine: A Critical Review

Copigmentation is a solution phenomenon in which pigments and other noncolored organic components form molecular associations or complexes. It generally results in an enhancement in the absorbance and in some cases, a shift in the wavelength of the maximum absorbance of the pigment. Copigmentation has not previously been taken into account in traditional wine color measures, in the relationship between color and pigment analysis, or in spectrophotometric assays for anthocyanin content. It is now apparent that copigmentation can account for between 30 and 50% of the color in young wines and that it is primarily influenced by the levels of several specific, noncolored phenolic components or cofactors. Copigmentation is of critical importance in understanding the relationship between grape composition and wine color, the variation in color and pigment concentration between wines, and in all reactions involving the anthocyanins during wine aging. This review focuses on the importance of the individual pigments and cofactors, the strength of their interactions, and their relative abundance in grapes and wines. A simple mathematical analysis of the solution equilibrium is developed to explain the nonlinear deviation from Beer’s law. When solved for typical wines, this function provides estimates of the apparent association constant, K, and the apparent molar extinction of the copigmented form, Ec, in natural mixtures. These measures allow the fraction of the anthocyanins which is in the copigmented form to be estimated. The significance of this phenomenon on pigment extraction and color retention during fermentations, on the rate of subsequent pigment polymerization, on the possible protection of anthocyanins from oxidation, and in the possible involvement on perceived mouthfeel and astringency of wines are suggested. Aspects of the copigmentation phenomenon that are poorly understood are identified and some research directions are suggested.

Colour effects of co-pigmentation of anthocyanins revisited—2.A colorimetric look at the solutions of cyanin co-pigmented byrutin using the CIELAB scale

Spectral measurements (380–780 nm) were performed on 224 model solutions of cyanin co-pigmented by the flavonol rutin at pH between 2.5 and 5.5. The colour of the solutions was expressed as colorimetric co-ordinates in the CIELAB scale using the L * (lightness) C * (chroma) and h (hue angle) notation (for the D65/10° CIE Illuminant/Observer condition). Contrary to previous reports, all the most intensely co-pigmented solutions, although exhibiting the strongest bathochromic of their λ max, did not displayed the bluest hues; an inverse, i.e. yellowing, effect was observed in the co-pigmented solutions at the lowest cyanin concentrations. The hyperchromic effect of co-pigmentation always caused a decreasing lightness of the solutions coupled with either an increasing or a decreasing chroma for those at low or high pigment concentrations respectively. Based on the amplitude of total colour CIELAB differences ( ΔE*) at each co-pigment to pigment ratio, the most intense effects of co-pigmentation were observed at pH 3.5, except for the solutions at the highest pigment content (pH 4.5); the evolution of colour differences at increasing co-pigment to pigment ratios at pH between 2.5 and 5.5 are discussed. Colour differences calculations also showed that the maximum colour steps at successive increasing co-pigment to pigment ratios were observed at low values (0.5 or 1:1) in the most coloured solutions and at the highest values (up to 8–16:1) in the less coloured ones. In describing the colour effect of co-pigmentation on anthocyanins, the discrepancies found between the results of the present colorimetric approach and those previously reported based on spectral data at the λ max only are discussed. Only the first one—by considering the spectral variations over the complete range of visible wavelengths and using the psychometric correlates of the three attributes of colour specified in the CIELAB system—correctly describes the colour variations as these are perceived by the human eye.

Colour effects of co-pigmentation of anthocyanins revisited—1. A colorimetric definition using the CIELAB scale

This method is based on a spectral curve recorded and considered over the full range of visible light and a subsequent colorimetric specification (CIELAB system, L ∗ , C ∗ , h notation for the D65/10 ° illuminant/observer condition) using the three attributes of colour perception, hue, lightness and saturation for a complete definition of the colours of anthocyanin solutions. Spectral and colour measurements were performed on model solutions of pure and co-pigmented (by quercetin 3-rhamno-glucoside) cyanin (cyanidin 3,5-diglucoside) at pH from 2.5 to 5.5. Regarding the colour of anthocyanin solutions, major discrepancies were found between the results of this colorimetric analysis and those formerly reported which were only based on variations of the visible λ max. As their concentration increased, pure cyanin solutions exhibited huge variations of hue (from magenta to orange) in their colour, although their λ max. remained stable. Contrary to usual reports concerning ‘the blueing effect’ of a spectral bathochromic shift, it was observed that the colour of solutions, as their visible λ max. moved higher, shifted either yellower or bluer, depending on the pH and concentration. As for colour variations caused by absorbance changes, this study showed that the currently employed term ‘intensity’ was quite ambiguous, indistinctly representing variations of two attributes of colour, saturation and lightness. Consequently, a revision of the effects of some chemical parameters on the colour of anthocyanin pigments is presented.

Blue flower colour derived from flavonol—anthocyanin co-pigmentation in Ceanothus papillosus

The pigments responsible for the blue flower colour of Ceanothus papillosus have been identified. The colour arises from co-pigmentation between the anthocyanins and flavonols. The major anthocyanins have been identified from NMR spectroscopy and degradation studies as the novel acylated delphinidin glycosides, delphinidin 3- O-rutinoside 7- O-(6- O- p-coumaroylglucoside 3′- O-glucoside and delphinidin 3- O- rutinoside 7,3′-di- O-(6- O- p-coumaroylglucoside), and the major flavonol is kaempferol 3- O-xylosyl-(1 → 2)- rhamnoside. The co-pigmentation effect appears to be quite specific, and does not occur to the same extent with other, more common, flavonols. The effect is particularly notable in that an extraordinary, long wavelength visible absorbtion maxima at 680 nm is produced which confers additional blueness. This is proposed to arise from a supramolecular complex of high stoichiometry. © 1997 Elsevier Science Ltd. All rights reserved

Anthocyanin–aluminium and –gallium complexes in aqueous solution

M. Elhabiri, P. Figueiredo, K. Toki, P. F. K. T. N. S. R. B., P. F. K. T. N. S. R. B. and R. Brouillard, J. Chem. Soc., Perkin Trans. 2, 1997, 355 DOI: 10.1039/A603851D