Copigmentation Effect Research Articles

Colorimetric study of malvidin-3-O-glucoside copigmented by phenolic compounds: The effect of molar ratio, temperature, pH, and ethanol content on color expression of red wine model solutions

In the recent research, the copigmentations of malvidin-3-O-glucoside with eight types of phenolic copigments have been investigated. The influence of the pigment/copigment molar ratio, the reaction temperature, the pH and the ethanol content of solutions has been examined. The results showed that the copigmentation effect was dependent on not only the particular structures of the phenolic compounds but also the factors of the reaction systems. The increase of the copigment concentration can strengthen the copigmentation effect, improve the solution color, and enhance the red-purple features. Different temperatures had different influences on the copigmentation reactions. The destruction of the copigmentation complexes can result in the hypsochromic shift of the reaction solution when the temperature was higher than 20°C. The bathochromic shift of the solution gradually progressed with the increase of the pH value. A significant copigmentation feature was spotted when pH reached 3.0, which demonstrates obvious red-purple characterization. The addition of the ethanol weakened the copigmentation effect. According to measurement through color analysis, it was found that the color differences caused by ethanol in red wine were typically attributed to quantitative changes. Remarkably, all of the above delicate color deviations caused by the structural or environmental factors can be precisely and conveniently depicted via the CIELAB space analysis.

Anthocyanins from purple sweet potato (Ipomoea batatas (L.) Lam.) and their color modulation by the addition of phenolic acids and food-grade phenolic plant extracts

Anthocyanin profiles and contents of three purple sweet potato provenances were investigated by HPLC-DAD-MSn. In contrast to widely uniform profiles, the contents of total (558–2477mg/100gDM) and individual anthocyanins varied widely. Furthermore, quantitative and qualitative effects of intermolecular co-pigmentation were studied by adding chlorogenic and rosmarinic acids, and food-grade phenolic apple and rosemary extracts at various dosages to a diluted purple sweet potato concentrate at pH 0.9, 2.6, 3.6, and 4.6. Addition of co-pigments generally increased pKH estimate-values of anthocyanins from 3.28 (without co-pigments) to up to 4.71, thus substantially broadening the pH range wherein colored forms prevail. The most pronounced hyperchromic shift by up to +50.5% at the absorption maximum was observed at pH 4.6. Simply by blending the co-pigments with purple sweet potato anthocyanins at pH-values ranging from 2.6 to 4.6, purplish-blue, light pink, magenta, brick-red, and intense red hues were accessible as expressed by CIE-L∗a∗b∗ color values.

Impact of Adding Ellagic Acid to Red Grapes on the Phenolic Composition and Chromatic Quality of Cabernet Sauvignon Wines from a Warm Climate

In this study, the effect of adding ellagic acid (Ea) before alcoholic fermentation on the phenolic composition and chromatic quality of Cabernet Sauvignon wines were investigated. The evolution of the color and polyphenolics was determined by tristimulus colorimetry and HPLC-MS during the industrial-scale winemaking process, which showed that the prefermentation addition of Ea could obtain more saturated and vivid hue wines, consistent with the significant increase in anthocyanins concentration. The copigmentation effect induced by Ea was also confirmed by the higher copigmentation degree in the treated samples. Thus, the addition of Ea could provide a simple and useful enological technique to enhance the red wine quality, improve the intensity and stability of wine color, and can be employed as an alternative strategy for obtaining high-quality red wines from a warm climate region (e.g., Xinjiang Uygur Autonomous Region, northwest China). Practical Application The main objective of this work is to evaluate the effect of adding Ea before alcoholic fermentation on color and phenolic compounds of red wines, which could be helpful in reasonably application of copigment additives and enlargement the understanding of the chemistry of interaction between this copigment and anthocyanins. Although the Ea is currently not approved for use in wines in somewhere of world, this addition treatment could provide a useful enological technique to enhance the intensity and stability of red wine color. For this reason, we believe that this study is valuable in providing useful insights for future research.

Co-pigmentation of pelargonidin derivatives in strawberry and red radish model solutions by the addition of phenolic fractions from mango peels

Pelargonidin-based colors suffer from notorious instability. A phenolic mango peel extract and defined phenolic fractions thereof were shown to effectively modulate the visible absorption of anthocyanins from strawberry (Fragaria x ananassa Duch.) and red radish (Raphanus sativus L.) by intermolecular co-pigmentation. Consistently, non-acylated pelargonidin derivatives from strawberry exerted significantly greater hyper- and bathochromic spectral shifts than their acylated counterparts from red radish. The addition of low molecular-weight co-pigments such as gallic acid and monogalloyl glucoses to strawberry anthocyanins led to strong hyperchromic shifts from 30% to 48%, while gallotannins (>six galloyl units) exerted smaller co-pigmentation effects (36±2%; Δλmax 13nm), possibly due to steric hindrances. In contrast, penta- and hexa-O-galloyl-glucose induced greatest and most stable co-pigmentation effects (53±2%; Δλmax 13nm). Irrespective of the underlying mechanisms and the responsible compounds, phenolic mango peel extracts might represent suitable color enhancers for coloring foodstuff, particularly for those containing non-acylated pelargonidin derivatives.

The Influence of Prefermentative Addition of Gallic Acid on the Phenolic Composition and Chromatic Characteristics of Cabernet Sauvignon Wines.

In this study, the prefermentative addition of gallic acid in Cabernet Sauvignon red winemaking was performed. The influence of gallic acid addition on wine phenolic composition, the ratio of copigmentation, and the color parameters were monitored throughout the winemaking process. The results showed that the prefermentative addition of gallic acid enhanced the extraction of total anthocyanins and the copigmentation effect, producing wines with more darkness, redness, yellowness, and saturation. Moreover, the addition of gallic acid contributed to the concentration of total phenolic acids. However, it had a negative effect on the concentrations of flavonols and flavan-3-ols in the final wines. Thus, the prefermentative addition of gallic acid at appropriate levels might be a promising enological technology to obtain wines with high color quality and aging potential.

Effect of genuine non-anthocyanin phenolics and chlorogenic acid on color and stability of black carrot (Daucus carota ssp. sativus var. atrorubens Alef.) anthocyanins

This work aimed at studying the color intensity and stability of black carrot anthocyanins as influenced by intermolecular co-pigmentation. For this purpose, purified anthocyanin solutions were supplemented with purified genuine black carrot phenolics, chlorogenic acid, and an aqueous phenolic-rich green coffee bean extract at various anthocyanin:co-pigment ratios (1:0–1:162; pH 3.6). The hyperchromic co-pigmentation effect depended on the concentration of added co-pigments, resulting in an absorbance increase of up to 22% at the absorption maximum. Anthocyanin stability during heating (90°C, 5h) was barely improved unless the concentrations of co-pigments exceeded those of their natural source. When adding co-pigments at ratios above 1:9.4, anthocyanin heat stability was significantly improved. As acylated anthocyanins were most stable, breeders might aim at increasing their content in the future, while breeding for high levels of colorless polyphenols may be unreachable. Nevertheless, we provided proof-of-concept for the successful color enhancement by the addition of a phenolic-rich green coffee bean extract, being useful for food-grade applications.

Analysis of anthocyanins and flavonols in petals of 10 Rhododendron species from the Sygera Mountains in Southeast Tibet

Flower color is one of the major ornamental characteristics of the genus Rhododendron, but few studies on flower color in alpine Rhododendron have been reported. In our study, the flower colors and the pigment constituents of petals from 10 Rhododendron species sampled in the Sygera Mountains of Southeast Tibet were analyzed using high-performance liquid chromatography-diode array detection and mass spectrometry (HPLC-DAD-ESI-MS2). The color analysis showed that the 10 Rhododendron species could be divided into five color groupings: yellow, red, red-purple, purple-violet, and purple. A total of 5 anthocyanin compounds and 23 flavonol compounds were tentatively identified and quantified. There were obvious differences in the composition of anthocyanin and flavonol among the petals of the 10 Rhododendron species. The color parameter L* decreased as the TA (total anthocyanin) content increased in the red-purple group. However, there was no obvious correlation between the L* value and the TA content in the other sampled Rhododendron species. In this study, the TA values of most of the Rhododendron species were quite low, but the TF (total flavonol) content was high. These results indicate the existence of copigmentation effects in these 10 Rhododendron species.

Copigmentation effects and thermal degradation kinetics of purple sweet potato anthocyanins with metal ions and sugars

The copigmentation effects of purple sweet potato anthocyanins (PSPAs) with metal ions and sugars were investigated in model solutions at pH 4. The thermal stability of PSPAs was also explored in the presence of sugars and 5-hydroxymethylfurfural (5-HMF). Copigmentation are characterized by hyperchromic effect and bathochromic shift. The hyperchromic effect of Fe3+ reached 25.15 % even at a very low concentration 0.005 mol L−1, while the values of the other metal ions at 0.05 mol L−1 were ranked in the following ascending order: K+ < Ca2+ < Mg2+ < Zn2+ < Cu2+ < Fe2+ < Al3+. The bathochromic shift was not observed in all sugar reaction solutions; glucose showed the highest values of hyperchromic effect at the concentration range 150–300 g L−1, followed by fructose and sucrose; konjac glucomannan showed the highest effect even at a much lower concentration among the macromolecular sugars. Especially, the konjac glucomannan exhibited a much better color enhancement than glucose. Small molecular sugars accelerated the thermal degradation of PSPAs, whereas macromolecular sugars showed a protective effect particularly at high temperatures. Moreover, 5-HMF resulted in the deterioration of the thermal stability of PSPAs and was suggested to be an important labile factor for copigmented PSPA solutions.

The Copigmentation Effect of Different Phenolic Acids onBerberis crataeginaAnthocyanins

In this study, the effect of copigmentation with phenolic acids i.e., tannic, gallic, ferulic and caffeic acids that have various pigment : copigment molar ratios (1:10; 1:50; 1:100) on Berberis crataegina anthocyanins at 90C was monitored. Copigmentation increased the stability anthocyanins. The increase in pigment : copigment ratios resulted differently on each phenolic acid compound, i.e., as the molar ratio increases in gallic acid copigmented samples, the anthocyanin degradation reduces, but conversely it increases in all the other acids used. Additionally, the compatibility of the degradation of copigmented anthocyanins to first order and Weibull distribution models were studied. In the result of the validation, Weibull distribution model was found to fit to better explain the anthocyanin change. The Weibull model half-lives of gallic (1:100) and ferulic acid (1:10) at given molar ratios were calculated as 111.17 and 91.92 min when compared to59.89 min of the control group. Practical Applications Color is an important quality criterion of a food product for consumers. When manufacturing conditions were taken into account, during storage, color bleaching and/or losses in foods might occur. For this reason, food-coloring additives are used to prevent color losses or enhance color. The most important group involved in natural colorants is anthocyanins. However, relatively low stability of anthocyanins compared to synthetic dyes has restricted their use as natural colorants. Components that form stable and different compounds by complexing with anthocyanins are called copigments. Although they are generally colorless when they are added to solutions containing anthocyanins, their color become stronger; stability of the color increases and their characteristics change.

Copigmentation between malvidin-3-O-glucoside and hydroxycinnamic acids in red wine model solutions: Investigations with experimental and theoretical methods

The copigmentation effect between malvidin-3-O-glucoside and three hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids) on the color expression was assessed in red wine model solutions. The colorimetric parameters indicated that the increasing concentration of these copigments could enhance the color intensity of the wine-like solutions (hyperchromic effect and bathochromic shift), and displayed the darker and more vivid bluish chromatic properties. The equilibrium constant (K), stoichiometric ratio (n) and thermodynamic parameters (∆G°, ∆H°, ∆S°) were determined by the spectrophotometric methods, showing the generally spontaneous exothermic character of the process. In addition, quantum chemical investigations were performed to interpret the absorption differences. The results showed that the ferulic acid was the more powerful copigment compared with the other two hydroxycinnamic counterparts, indicating that the copigmentation was not only correlated to the concentration of the copigments but also strongly dependent on their molecular structures. AIM analysis was also used to explore the driving forces contributing to the copigmentation, which suggested that the hydrogen bond and van der Waals interactions were the main driving forces for the three pigment–copigment complexes.

Mimicking Positive and Negative Copigmentation Effects in Anthocyanin Analogues by Host-Guest Interaction with Cucurbit[7]uril and β-Cyclodextrins.

Copigmentation and the anti-copigmentation effects can be mimicked by the interaction of anthocyanin's model compounds respectively with cucurbit[7]uril (CB7) and β-cyclodextrin (β-CD). The complex network of chemical reactions displayed by this family of compounds includes the colored flavylium cation, AH(+), and quinoidal base, A, along with the colorless hemiketal, B, cis-chalcone, Cc, and trans-chalcone, Ct. Whereas AH(+) is stable only at very acidic pH values, the remaining species are formed at slightly acidic and neutral conditions. However, under these conditions, for most of the natural and synthetic flavylium salts, the colorless species predominate (B, Cc, and Ct) at the expense of A. The host CB7 was found to improve the color of solutions in two different ways: first, it stabilizes AH(+) at higher pH values by decreasing its acidity and, second, it enhances the mole fraction of A due to selective complexation of this species in the pH range where the flavylium cation is no longer stable. In contrast, β-CD increases the acidity of AH(+), favoring the formation of Ct at the expense of all the other multistate species (Bası́lio et al. New J. Chem. 2013, 37, 3166-3173; Petrov et al. J. Phys. Chem. A 2013, 117, 10692-10701; Gago et al. Dyes Pigments 2014, 110, 106-112; and Lopes-Costa et al. Photochem. Photobiol. Sci. 2014, 13, 1420-1426). Although both hosts have a large effect on the hydration rate and pH domain of the flavylium cation, the effect on the degradation kinetics of anthocyanidins is modest. CB7 decreases the hydration rate and decreases the acid-base (AH(+)/A) equilibrium constant (Ka), leading respectively to a slowing and a speeding of the anthocyanin degradation rate. On the other hand, β-CD increases the hydration rate but increases Ka, both effects acting in opposite directions.

Copigmentation of malvidin-3-O-glucoside with five hydroxybenzoic acids in red wine model solutions: Experimental and theoretical investigations

In the present research, the copigmentations of malvidin-3-O-glucoside with five hydroxybenzoic cofactors (p-hydroxybenzoic acid, protocatechuic acid, gallic acid, vanillic acid, and syringic acid) were investigated. The influence of the concentration of these cofactors and the reaction temperature was examined. The equilibrium constant (K), stoichiometric ratio (n) and the thermodynamic parameters (ΔG°, ΔH°, ΔS°) related to the copigmentation were also reported here. Theoretical calculations were performed to identify the relative arrangement between the pigment and cofactors in the copigmentation complexes. Besides, the comparison of the relative binding free energies (ΔΔGbinding) derived from the theoretical calculations and experimental data were made, and the binding strength of these copigmentation complexes was discussed with the interaction energies (ΔE). AIM analysis was also used to explore the main driving forces contributing to the copigmentation. In the comparison of the five studied cofactors, syringic acid had a stronger copigmentation effect than the other four phenolic acids investigated.

Complexing of chlorogenic acid with β-cyclodextrins: Inclusion effects, antioxidative properties and potential application in grape juice

Chlorogenic acid (CGA) is a polyphenol commonly existed in fruits and vegetables with a variety of bioactivities. To increase its stability and potential broader industrial application, CGA/cyclodextrin (CD) complexes were prepared using β-cyclodextrin (β-CD) and its derivative (2-hydroxypropyl)-β-cyclodextrin (2-HP-β-CD). Their inclusion complexation behavior and characterization were investigated by FT-IR, XRD, SEM, and 1H NMR spectroscopy. The morphologic and spectral studies indicated the formation of inclusion complexes. Moreover, spatial arrangements of inclusion complexes were proposed based on 1H NMR results. The antioxidant activities of the complexes were improved compared with the CGA without inclusion, and the CGA/HP-β-CD complexes showed the highest antioxidant activity. In addition, the CGA/CD complexes were added in grape juice to explore the potential on the preservation of anthocyanin and color quality. Results showed that the degradation of anthocyanins was reduced when CGA and CGA/CDs inclusions were added in grape juice due to copigmentation effect, and their copigmentation strength showed in an order of CGA/HP-β-CD complex > CGA/β-CD complex > free CGA.

The Effects Catechin on Stability of Grape Anthocyanin – Copigment Complex

The color of anthocyanins is unstable and quickly decolourized by reactions. Thus anthocyanins in living cells may have mechanisms for resistance to maintain color stability. Copigmentation is the main color – stabilizing mechanism. In this study copigmentation of anthocyanin in Seedless Red grape were investigated with catechin copigment. The dependence of the copigmentation process on the heating, UV and copigment concentration was studied. Five levels of copigment concentrations as: 0, 120, 240, 480, 960 (mg/l) were examined. The copigmentation effects increased with copigment contain. During UV irradiation, anthocyanin-copigmentation complex showed higher stability in comparison with anthocyanins. Also UV irradiation has the biggest effect on the copigmentation complex in comparision with heating. Keyword: Anthocyanin, Catechin, Copigment, Heating, Seedless Red

The Effect of Copigmentation on the Stability of Butterfly Pea Anthocyanins

The objective of this research was to study the effects of co-pigmentation on the colour display and stability of Butterfly Pea extracts with plant extracts under different pH. The scopes of the work focus on the effect on co-pigmentation of the Cinnamon, Cumin and Turmeric extract on the colour display. The effects on colour enhancement and the stability of Butterfly Pea extract were evaluated. LC/MS/MS analysis shows that the anthocyanin in Butterfly Pea is highly acylated and therefore, is stable due to intramolecular copigmentation. The flavonoids content in Cinnamon extract was identified as Cinnamtannin B1(m/z 864.7, MW 864.7156) while in.Cumin extract, Apigenin 7-galacturonylglucoside (m/z 609.409, MW 608.524) and Luteolin 7-digalacturonide-4-glucoside (m/z 625.376, MW 624.376) were presented. Dimethoxycurcumin (m/z 394.2, MW 394.0134 and m/z 313.0, MW 312.975) was identified in Turmeric extract. Turmeric was suggested as the best copigment for Butterfly Pea since it showed the highest hyperchromic shift (61.41%), followed by Cinnamon extract (17.04%) and Cumin extract (16.08%).

Copigmentation of Mahonia Bealei Anthocyanins by Tannin

This study investigates the copigmentation effect and its underlying mechanism of tannin on Mahonia bealei anthocyanins (MBA). Results show that the addition of tannin increases the absorption and maximum absorption wavelength of MBA. At pH 3.73, the activation energy of MBA-tannin adduct is 2.43 times that of MBA. Under the same temperature, MBA-tannin complex shows better heat stability as exemplified by lower degradation rate and longer half-time. The light-induced degradation rate constant of MBA-tannin is 93.33% of that of MBA. It is shown in this paper that tannin can improve the heat and light stability of MBA and therefore is efficient as a copigment. Finally, the IR spectra suggest that the copigmentation effect is due to the formation of hydrogen bonds between tannin and MBA via associated hydroxyl groups.

Tuning color variation in grape anthocyanins at the molecular scale

Anthocyanins are the main grape pigments. Due to their aromatic cyclic arrangements, they are able to absorb the radiation in the low energy range of the visible spectrum. In the fruit of Vitis vinifera L., the five main anthocyanidins (cyanidin, peonidin, delphinidin, petunidin and malvidin) are present as 3-O-glucosides, as well as their acetyl, p-coumaroyl and caffeoyl ester forms. Despite the huge number of experimental studies dedicated to the anthocyanin profile analysis of grapes and wines, the complete theoretical elucidation of the optical properties of grape anthocyanins is missing. The present work carried out this task through quantum chemistry calculations based on time-dependent density functional theory (TD-DFT), compared to experimental spectra. The differences in visible absorption spectra between the most common grape anthocyanins were rationalized according to B-ring substitution, glucosylation and esterification. A particular attention was given to the intra-molecular copigmentation effect, demonstrating the existence of an intra-molecular charge transfer excited state for the p-coumaroyl and caffeoyl ester forms.

Poor Interoperability of the Adams-Harbertson Method for Analysis of Anthocyanins: Comparison with AOAC pH Differential Method

The poor interoperability of anthocyanin glycosides measurements by two pH differential methods is documented. Adams-Harbertson, which was proposed for commercial winemaking, was compared to AOAC Official Method 2005.02 for wine. California bottled wines (Pinot Noir, Merlot, and Cabernet Sauvignon) were assayed in a collaborative study (n=105), which found mean precision of Adams-Harbertson winery versus reference measurements to be 77 +/- 20%. Maximum error is expected to be 48% for Pinot Noir, 42% for Merlot, and 34% for Cabernet Sauvignon from reproducibility RSD. Range of measurements was actually 30 to 91% for Pinot Noir. An interoperability study (n=30) found Adams-Harbertson produces measurements that are nominally 150% of the AOAC pH differential method. Large analytical chemistry differences are: AOAC method uses Beer-Lambert equation and measures absorbance at pH 1.0 and 4.5, proposed a priori by Flueki and Francis; whereas Adams-Harbertson uses "universal" standard curve and measures absorbance ad hoc at pH 1.8 and 4.9 to reduce the effects of so-called co-pigmentation. Errors relative to AOAC are produced by Adams-Harbertson standard curve over Beer-Lambert and pH 1.8 over pH 1.0. The study recommends using AOAC Official Method 2005.02 for analysis of wine anthocyanin glycosides.

Copigmentation and anti-copigmentation in grape extracts studied by spectrophotometry and post-column-reaction HPLC

Copigmentation is a very important contributor to colour in young red wines. Further understanding of the copigmentation effect has been elucidated by investigating the contribution of various fractions of grapes – skin, pulp, and seed – in varieties Shiraz, Sangiovese and Pinot Noir. A series of spectrophotometric and HPLC experiments elucidated the effect of this interaction in grape extracts simulating wine conditions. A post-column reaction method was developed to permit the evaluation of the reactivity of each grape anthocyanin with different reagents: pure compounds (quercetin and caffeic acid) and extracts of grape sections (seed, Semillon skin, Semillon pulp). Certain extracts produced a decrease in colour, suggesting that competing equilibria are important in the copigmentation effect and that an “anti-copigmentation” effect is possible. Flavonols appear to be the best copigmentation cofactors, and the concentration of quercetin 3-O-glucoside was found to correlate with the strength of copigmentation. Flavonols appear capable of displacing cofactors derived from seed extracts.

Interactions of natural antioxidants with red grape pomace anthocyanins in a liquid model matrix: Stability and copigmentation effects

The purpose of this study was an examination on the stability and colour enhancement of red grape pomace anthocyanins in a juice model matrix, and the effect of the addition of natural antioxidants. The approach was based on a juice-like liquid medium (10.1?Brix, pH 3.48), which was used as the model matrix to test the effect of the addition of natural antioxidants (L-cysteine, ascorbic acid, catechin and quercetin) on the degradability of anthocyanin pigments, extracted from grape pomace. It was found that treatment of the model solutions at 80?C induced anthocyanin decomposition, which obeyed first order kinetics. Addition of increasing amounts of antioxidants, including L-cysteine, ascorbic acid, catechin and quercetin, did not provoke a proportional impact, either positive or negative, with regard to anthocyanin stability. The best stabilising effect was seen after addition of ascorbic acid and catechin at concentrations of 4 and 2 mg L-1, respectively (P &lt; 0.001). Quercetin, however, was demonstrated a very efficient co-pigment, inducing an increase in A520 by 63%, at pH 5.6 and a copigment-to-pigment ratio of 10.