Copigmentation Effect Research Articles

Copigmentation effect on red cabbage anthocyanins, investigation of their cellular viability and interaction mechanism

Anthocyanins (ANS) are an appealing substitute to synthetic colorants; but their practical applicability is limited due to low color stability. Copigmentation can improve both complex’s color stability as well as intensity. In this study, we examined the interaction of red cabbage ANS with copigments i.e., two organic acid, two phenolic acid, a flavonoid and three amino acid through experimental and theoretical approach. Among various copigments, phenolic and organic acids induced a strong bathochromic shift of 6.5–7.1 nm and 5.1–11.6 nm. Thermal analysis, anthocyanin content and chromaticity, were used to assess the color intensity and stability of ANS, at 4 ℃, 25 ± 2 ℃, sunlight, oxygen, and heat. Results revealed that oxalic acid copigmented complex followed by chlorogenic and rosmarinic acid exhibits significant thermal stability with greater retention rate at 120 ℃ and 150 ℃. In case of anthocyanin content and colorimetric parameters, chlorogenic acid followed by oxalic and rosmarinic acid exhibits significantly improved stability. Rosmarinic acid copigmented sample showed good cell viability at high concentration (200 µg/mL). Steered molecular dynamics and thermodynamic analysis reveals chlorogenic and rosmarinic acid as promising copigments involving conventional H-bonds, π-π interactions, and carbon hydrogen bonds.

3D printing cassava starch-ovalbumin intelligent labels: Co-pigmentation effects of gallic acid on anthocyanins

Anthocyanins are often chosen as signal converters of intelligent labels. However, they are degraded by high-temperature oxidation in the process of intelligent label preparation. The color fading seriously affects the sensitivity of color development. In this study, a green 3D printing intelligent label preparation technique was developed, in which gallic acid (GA) was added to a blueberry anthocyanin (BA) solution to enhance the color of the co-pigment to ensure the color sensitivity. The combined effect of GA-BA reduced the fade rate of the anthocyanins from 35.13 % to 26.44 % at 90 °C. The printing ink has shear-thinning viscosity characteristics and yield stresses in the range of 500–600 MPa for high-quality printing. Structural analysis revealed that GA-BA co-pigmentation enhanced the interaction between ovalbumin and cassava starch. In addition, the method of 3D printing to prepare labels was conducive to solving the problem of waste in traditional labeling process. The results of freshness testing of sea shrimp proved that labels can be applied to fresh boxes to reflect the freshness of food. We provide a method for enhancing the color of 3D-printed smart ink to prepare intelligent labels with reproducible and customizable batch shapes.

Exploring the impact of substitution and conformational variations on the copigmentation ability of monomeric flavan-3-ols in wine

Monomeric flavan-3-ols are important copigments in red wines, due to their superior copigmentation ability and high concentration. In this work, a systematic study was conducted on the copigmentation effects of eight common monomeric flavan-3-ols with malvidin-3-O-glucoside, using experimental and theoretical methods. The results revealed that the addition of a hydroxy group to the B ring and the attachment of a galloyl group at the 3-O position of monomeric flavan-3-ols both contributed to enhance copigmentation, with the latter exerting a more pronounced effect. Regarding stereoisomerism, it was observed that the cis-configuration of the B ring and 3-O-hydroxy group favored copigmentation. However, the cis-configuration of the B ring and 3-O-galloyl group was disadvantageous due to steric hindrance, in contrast to when these moieties occupied opposing sides (i.e., the 2,3-trans configuration). These results highlight the crucial role played by both substitution patterns and conformational arrangements in determining the copigmentation ability of monomeric flavan-3-ols.

Novel nanoparticle composed by Ovalbumin-OSA modified pectin-rutin for improving the stability of Monascus pigments

To improve the resistance of Monascus pigments (MPs) to adverse environmental factors, a nanoparticle carrier was constructed using ovalbumin, rutin and pectin modified by octenyl succinic anhydride. According to the determination of particle size, ζ-potential and microstructure, the composite nanoparticles exhibited the "core-shell" structure. Specifically, the ovalbumin core was encapsulated by the modified pectin adsorbed with rutin. Spectroscopic analysis demonstrated that electrostatic interactions, hydrogen bonding and hydrophobic interactions between wall materials and MPs were the main driving forces to form composite nanoparticles. The stabilities of light, thermal and storage of MPs were significantly enhanced after encapsulation due to the physical barrier effect of the wall materials against external disturbances and the multiple functions of rutin, including free radical scavenging, absorption of partial UV and scatter light, and possible co-pigmentation effects with MPs. Moreover, the composite nanoparticles exhibited higher inhibition activity against pancreatic lipase and antioxidant activity compared with those of free MPs. The results provided an ideal way to develop new MPs products, which had long-lasting and stable performance during food processing and storage.

Indicator-enhanced starch-based intelligent film for nondestructive monitoring of beef freshness: Different structural phenolic acids copigment anthocyanin

Intelligent, non-destructive visual monitoring of food freshness is an emerging trend in intelligent food packaging in which highly sensitive, intelligent films are required to achieve monitoring accuracy. Hence, a highly sensitive, pH-responsive, intelligent indicator film for the real-time monitoring of beef freshness was prepared using phenolic acid-copigmented blueberry anthocyanin. UV-scanning spectroscopy confirmed that the phenolic acids exhibited colour-enhancing effects. The specific effect was different due to the different structures. The highest M value (97.98) demonstrated that ferulic acid with methoxylated has the strongest copigmentation effect. Degradation kinetics for the copigmentation of phenolic acids with anthocyanins proved that FA had the slowest degradation rate and the longest half-life (2.89 d/21.13 d) under both light and heating conditions. This proved that FA also had the best stabilizing effect on anthocyanin. FTIR demonstrated that the two bind by hydrogen bonding and π–π stacking interactions. The thermodynamic parameters revealed that different binding energies might be responsible for the differences in colour enhancement. The highest K (5.3672) and negative ΔG (−4.1631 kJ mol−1) provide theoretical support for the optimal copigmentation that can be produced by FA. The results of pH acid-base reversible responsiveness and stability tests show that FA enhanced the colour stability and indication response sensitivity of the intelligent film through copigmentation, and improved the visual identification. The film copigmented by FA was applied to beef monitoring results, which accurately identified sub-fresh portions, indistinguishable to the naked eye, where the beef was at a threshold of spoilage. Intelligent program application further standardises individual visual behaviours and improves film accuracy. This proved that ferulic acid improved the practical application value of the intelligent indicator film loaded with anthocyanin through copigmentation.

Intermolecular interactions between malvidin-3-O-glucoside and caffeic acid: Structural and thermodynamic characterization and its effect on real wine color quality

The copigmentation effect between malvidin-3-O-glucoside and caffeic acid was comprehensive inquiry on the model wine solution, theoretical simulation and real wine. Thermodynamic parameters were determined by UV/Visible spectroscopy and Isothermal titration calorimetry (ITC). Theoretical data were obtained employing a dispersion-corrected density functional approach. The effects in real wines were investigated by adding the caffeic acid during different fermentation periods. Results shown that the copigmentation reaction between caffeic acid and malvidin-3-O-glucoside is a spontaneous exothermic reaction driven by hydrogen bonding and dispersions forces. Computations show that the polyhydroxyl sugar moiety and phenolic hydroxyl groups are the key active sites. The addition of caffeic acid in post-alcohol fermentation samples evidences an improving color characteristics in the wine.

Gallic acid improves color quality and stability of red wine via physico-chemical interaction and chemical transformation as revealed by thermodynamics, real wine dynamics and benchmark quantum mechanical calculations

The aim of this study was to explore the copigmentation effect of gallic acid on red wine color and to dissect its mechanism at the molecular level. Three-dimensional studies, e.g., in model wine, in real wine and in silico, and multiple indicators, e.g., color, spectrum, thermodynamics and phenolic dynamics, were employed. The results showed that gallic acid significantly enhanced the color quality and stability of red wine. Physico-chemical interactions and chemical transformations should be the most likely mechanism, and physico-chemical interactions are also a prerequisite for chemical transformations. QM calculations of the physico-chemical interactions proved that the binding between gallic acid and malvidin-3-O-glucoside is a spontaneous exothermic reaction driven by hydrogen bonding and dispersion forces. The sugar moiety of malvidin-3-O-glucoside and the phenolic hydroxyl groups of gallic acid affect the formation of hydrogen bonds, while the dispersion interaction was related to the stacking of the molecular skeleton.

Differences in the Behavior of Anthocyanin Coloration in Wines Made from Vitis vinifera and Non-vinifera Grapes

The skins of Vitis vinifera species contain 3-glucosyl anthocyanins (3G), but some non-vinifera species, such as ‘Yama Sauvignon’ (YS), contain a large amount of 3,5-diglucosyl anthocyanins (35DG), and the behavior of anthocyanin coloration with respect to pH is quite different. The anthocyanins of YS showed a very weak color at a pH of 3 or higher but a very strong color below a pH of 3. Furthermore, when we investigated the effect of co-pigmentation in commercially available wines, we found that YS red wine contained a large amount of co-pigmented anthocyanins, and even wine aged for about 4 years contained a large amount of co-pigmented anthocyanins. Due to concerns regarding disease resistance, many hybrid varieties of V. vinifera and non-vinifera species have been bred, but it is important to take these special properties of 35DG into consideration when producing wine.

The effects of polysaccharides, organic acids and colloids on the stability of anthocyanin in purple corn

SummaryPurple corn anthocyanins have rich nutritional value, but anthocyanins have low stability. The main objective of this study was to screen compounds from the common co‐pigments (polysaccharides, organic acids and colloids) that could improve the stability of anthocyanins and to investigate the effect of different co‐pigments on the stability of anthocyanins in purple corn during heat treatment. There were significant differences in copigmentation effects among different types of co‐pigments. The total anthocyanin retention rate of purple corn without co‐pigments was 15.02%. After copigmentation treatment with different compounds, among the polysaccharides, the total anthocyanin retention rates of 15% fructose and 15% glucose were 37.29% and 52.18% respectively. The copigmentation effects of monosaccharides were better than those of disaccharides, sugar alcohols and cyclodextrins. Among the organic acids, the six co‐pigments were all organic acids containing phenolic rings. The retention rates of anthocyanins were 71.47% and 68.21% for 0.06% tannic acid and 0.1% tartaric acid, respectively, indicating high copigmentation effects. The a* value of purple corn was significantly increased after these treatments, indicating that organic acids had stronger copigmentation effects than polysaccharides. In the colloids, the total anthocyanin retention rate of 2.0% pectin was 43.72%, while 0.5% guar gum had a retention rate of 9.82%. However, low concentrations of guar gum promoted the degradation of anthocyanins, indicating weak copigmentation effects for colloids.

Co-pigmentation of Pinotage anthocyanins with Cyclopia (honeybush) polyphenols in model wine solutions

Co-pigmentation of an anthocyanin-enriched fraction (AEF) of Pinotage wine with honeybush polyphenols (Cyclopia subternata extract and fractions enriched in specific polyphenols) was studied in model wine solutions. The hyperchromic effects and bathochromic shifts depended on the co-pigment sources and co-pigment/anthocyanin ratio. Fraction 2 (F2), enriched in xanthones (mangiferin and isomangiferin), produced the most pronounced co-pigmentation effect at a co-pigment/anthocyanin ratio of 15:1. Greater co-pigmentation effects were observed in model solutions at pH 3.0 (pH 3–4 evaluated) and in the absence of EtOH (0–16 % EtOH evaluated). During storage of solutions (AEF and/or F2) at 15 °C and 25 °C for 12 weeks, myrtillin, petunin, 3′,5′-di-β-D-glucopyranosyl-3-hydroxyphloretin and mangiferin concentrations decreased following first-order kinetics, while peonin and oenin degradation followed fractional-conversion kinetics. Polymeric anthocyanin formation followed zero-order kinetics. Reaction rates increased with an increase in storage temperature. The addition of F2 to the AEF solution produced a darker, more vivid colour and improved the colour stability, however, the yellow-orange colour of F2 and intensification of its colour during storage contributed to increasing red-orange hues. Further research is necessary to elucidate the effect of honeybush polyphenols on the colour and composition of a complete wine as it is more complex than model solutions.

RuBisCo can conjugate and stabilize peonidin-3-O-p-coumaroylrutinoside-5-O-glucoside in isotonic sport models: Mechanisms from kinetics, multispectral, and libDock assays

The co-pigmentation behaviour of RuBisCo proteins (with different concentrations) on peonidin-3-O-p-coumaroylrutinoside-5-O-glucoside (P3C5G, extracted from Rosetta potato's peels) conjugates in isotonic sport drinks (ISD) was examined using multispectral, thermal stability kinetics, and libDock-based molecular docking approaches. The colorant effects of RuBisCo on P3C5G were also studied in spray-dried microencapsulated ISD-models. RuBisCo, especially at a concentration of 10 mg/mL in ISD, showed a co-pigmentation effect on the color of P3C5G, mostly owing to its superior hyperchromicity, pKH-levels, and thermal stability. Results from multispectral approaches also revealed that RuBisCo could noncovalently interact with P3C5G as confirmed by libDock findings, where P3C5G strongly bound with RuBisCo via H-bonding and π–π forces, thereby altering its secondary structure. RuBisCo also preserved color of P3C5G in ISD-powdered models. These detailed results imply that RuBisCo could be utilized in ISD-liquid and powder models that might industrially be applied as potential food colorants in products under different conditions.

Enhancing the storage stability of mulberry anthocyanin extract through ternary complex with whey protein isolate and ferulic acid at neutral pH: Investigation of binding mechanisms

Mulberry anthocyanin extract (MAE) is a valuable natural pigment with potential applications in the food industry. However, its storage stability remains a challenge, as it is prone to degradation over time. To tackle this issue, the present study focuses on investigating the efficacy of utilizing whey protein isolate (WPI) and ferulic acid (FA) in combination at pH 6.3. The addition of FA reduced the ΔE values and the degradation of anthocyanin within MAE solution in the presence of WPI. Notably, the combination of WPI and FA exhibited a remarkable stabilizing effect on the MAE solution. Multi-spectroscopic analysis revealed the occurrence of non-covalent interactions mediated by hydrophobic interaction between β-lactoglobulin (β-LG) and cyanidin-3-O-glucoside (C3G) in the presence of FA, with improved binding affinity. While FA did not exhibit a copigmentation effect on the C3G solution, it enhanced the protective action of β-LG on the chromophoric structural form of C3G. Moreover, although the introduction of FA to the β-LG complex with C3G resulted in minor modifications to the secondary structure, in contrast to the binary complexes, its particle size increased. The molecular dynamics simulations also revealed that FA enhances the binding affinity between β-LG and C3G. These findings provide a foundation for enhancing the storage stability of anthocyanins and expanding the utilization of MAE pigment in the food industry.

Effect of co-pigments on anthocyanins of Rhododendron arboreum and insights into interaction mechanism.

The impact of intermolecular copigmentation between five phenolic acids, two flavonoid and three amino acids with R. arboreum anthocyanins (ANS) and its isolated cyanidin-3-O-monoglycosides were investigated through experimental and theoretical approach. On addition of different copigments, phenolic acid induced strong hyperchromic (0.26-0.55nm) and bathochromic shift (6.6-14.2nm). The color intensity and stability of ANS with, storage at 4°C & 25°C, sunlight, oxidation and heat were evaluated by chromaticity, anthocyanin content, kinetic and structural simulation analysis. The strongest copigmentation reaction was observed with narningin (NA) and also showed high thermostability and highest half-life i.e. 3.39h-1.24h at 90-160°C. The cyanidin-3-O-monoglycosides were analysed for their copigmentation effect and observations revealed that NA displayed best copigmentation effect to cyanidin-3-O-arabinoside (B) followed by cyanidin-3-O-galactoside (A), and cyanidin-3-O-rhamnoside (C). Additionally, structural simulation and steered molecular dynamics insights NA is the most favourable co-pigment involving π-π stacking and H-bonding.

Dual-function β-cyclodextrin/starch-based intelligent film with reversible responsiveness and sustained bacteriostat-releasing for food preservation and monitoring

The full combination of high sensitivity indication and long-lasting bacteriostatic function is an innovative need to meet the practicality of intelligent film packaging systems for food products. Hence, Blueberry anthocyanins (BA) copigmentated by ferulic acid (FA) was used as an indicator, and cinnamon essential oil (CO) encapsulated by β-cyclodextrin (β-CD) as a bacteriostat, potato starch (PS) as a film-forming substrate to prepared a dual-function starch-based intelligent active packaging film with pH indicator and antibacterial function. FA had the best copigmentation effect with a threefold increase in a value compared to other phenolic acids. The ΔE value increased from 3.24 to 5.13 at pH 2–8, and the change was still prominent in acid-base alternating test, indicating a high response sensitivity. Notably, the yellow gamut of indicating terminus increased its visibility to the naked eye. The release behavior of CO from film was in line with Fick's diffusion. Meanwhile, the release of CO delayed to about 90 h through β-cyclodextrin encapsulation, showing a high growth-inhibition rate in E. coli and S. aureus of almost 100 %. In this study, a dual-function film with indication and bacteriostasis was prepared and enhanced with both, expanding its wide application in intelligent packaging of fresh food.

Storage stability and multi-spectroscopy analysis of the ternary complex induced by mulberry anthocyanin extract interacting with whey protein isolate and rutin under acidic conditions

In the present study, we have investigated the relevant mechanisms underlying the stabilizing effects of whey protein isolate (WPI) and rutin (Ru) on the mulberry anthocyanin extract (MAE) solution at pH 3.6 during storage. The results demonstrated that there was no pronounced difference in color between the MAE solutions when adding WPI and Ru separately and together. However, the combined use of WPI and Ru reduced the total anthocyanin degradation rate by 16.2% and 18.3% compared to WPI and Ru used individually, respectively, after 9 days of storage at 40 °C. Fluorescence, UV–visible, Fourier transform infrared, and circular dichroism spectroscopies, as well as particle size and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, indicated that the formation of binary and ternary complexes involving β-lactoglobulin (β-LG), cyanidin-3-O-glucoside (C3G), and Ru. The primary interaction between β-LG and C3G was electrostatic interaction, with an enthalpy change (ΔH) of −25.02 kJ mol−1 and an entropy change (ΔS) of 7.89 J mol−1 K−1 at 298 K, whereas the interactions between β-LG and Ru involved hydrogen bonding and van der Waals force, with ΔH of −124.80 kJ mol−1 and ΔS of −291.72 J mol−1 K−1 at 298 K. Furthermore, a looser, more open, and disordered structure and larger particle size were observed in protein after the addition of C3G/Ru. The presence of Ru in the ternary complex favored the development of these characteristics. Overall, to protect anthocyanins, β-LG and Ru could exert complexation and copigmentation effects on C3G, respectively. The findings of this study provide a foundation for employing ternary complexes to increase the storage stability of anthocyanins.

Effect of five polyphenols on the stability of purple cabbage anthocyanins in simulated beverage systems containing L-ascorbic acid

Purple cabbage shows great potential as a natural colorant source for commercial beverages due to its high anthocyanin content and wide availability. However, the application of purple cabbage anthocyanins in the food industry is limited by its unstable characteristics. This study aimed to investigate the effect of 0.4% concentration of catechin, epigallocatechin gallate, vanillin, gallic acid (GA), and rosmarinic acid on the stability of purple cabbage anthocyanins in beverage systems. The results showed that all five polyphenols increased the color intensity of anthocyanins and the copigmentation effect increased with the increased polyphenol. Five polyphenols were observed to enhance the color and thermal stability of anthocyanins in beverage systems, while GA performed best. The addition of GA to the beverage systems achieved a greater improvement in color stability regarding absorbance value (increased by 247.70%) and total color change (decreased by 70.34%). In addition, degradation kinetic reaction showed the lowest k (0.0466 1/d) and highest t1/2 (14.87 d) for anthocyanin degradation with GA addition. This study provides a potential solution to enhance anthocyanin stability and extend beverage shelf life through GA addition.

Flower colors and anthocyanins in the cultivars of Campanula medium L. (Campanulaceae)

Flower colors and anthocyanin composition of five cultivars of the Campanula medium “May series” were surveyed to determine the relationship between their corolla colors and anthocyanins. Eleven anthocyanins and chlorogenic acid were isolated from the flowers of these cultivars, and their structures were identified using chemical and spectroscopic methods. Among them, two novel anthocyanins, cyanidin 3- O -[6- O -(α-rhamnosyl)-β-glucoside]-7- O -[6- O -(4- O -(6- O -(4- O -(β-glucosyl)- p -hydroxybenzoyl)-β-glucosyl)- p -hydroxybenzoyl)-β-glucoisde] and pelargonidin 3- O -[6- O -(α-rhamnosyl)-β-glucoside]-7- O -[6- O -(4- O -(β-glucosyl)- p -hydroxybenzoyl)-β-glucoside] were discovered in the corollas in cultivars of ‘May Purple Marden’ and ‘May Pink’. Moreover, cyanidin 3- O -[6- O -(rhmnosyl)-glucoide]-7- O -glucoside, pelargonidin 3- O -[6- O -(rhmnosyl)-glucoide]-7- O -glucoside, and delphinidin 3- O -[6- O -(rhamnosyl)-glucoside]-- O -[6- O -(4- O -(6- O -(4- O -(glucosyl)- p -hydroxybenzoyl)-glucosyl)- p -hydroxybenzoyl)-glucoside] were also discovered in these cultivars for the first time in C. medium flowers. The anthocyanin structures, conditions, and concentration and their intramolecular co-pigmentation effect might be involved in flower color variation in C. medium cultivars. • Two new anthocyanins were isolated from the flowers of Campanula medium . • The structures were elucidated on the basis of chemical and spectroscopic data. • Flower color variation was due to anthocyanin pattern and intramolecular co-pigment effect.

Improved thermal stability of roselle anthocyanin by co-pigmented with oxalic acid: Preparation, characterization and enhancement mechanism

The enhancement effects of co-pigmentation on thermal stability of roselle anthocyanin extract (RAE) were investigated. The introduction of organic acids maintained color stability of RAE, and RAE co-pigmented with oxalic acid (OA) presented less color fading rates (19.46 ± 0.33 %) and higher redness (41.33 ± 3.51). Subsequently, suitable co-pigmentation concentration (OA:RAE = 1:2) was obtained regarding with lower ΔE (48.70 ± 2.36). Then, improvement behaviors of co-pigmentation on OA-RAE were evaluated. Results demonstrated that OA-RAE exhibited better thermal stability, as manifested by larger retention rates and more favorable thermal degradation kinetic parameters. Furthermore, both molecular docking simulation and experimental structural characterization revealed that hydrogen bonds and other non-covalent bonds made up the main parts of molecular interactions, leading to formation of stable binary complex. As a result, the aromatic ring of RAE was protected. In conclusion, the co-pigmentation of RAE via introduction of OA was effective in stability enhancement due to the generation of molecular bindings.

Investigation of the difference in color enhancement effect on cyanidin-3-O-glucoside by phenolic acids and the interaction mechanism

Co-pigmentation effect of phenolic acids on cyanidin-3-O-glucoside (C3G) and the mechanisms were investigated. Sinapic acid (SIA), ferulic acid (FA), p-coumaric acid (p-CA) and syringic acid (SYA) significantly enhanced C3G stability (P < 0.05), whereas vanillic acid (VA) and gallic acid (GA) showed no influence (P > 0.05). Among these phenolic acids, SIA and FA had higher binding coefficient with C3G (48.83 and 43.38), reduced degradation rate constant by 40.0 ∼ 50.0 %, prolonged half-life by 74.6 ∼ 94.7 % at 323 K, and significantly inhibited C3G hydration reaction (pKh = 2.87 and 2.80, P < 0.05). Molecular docking revealed that C3G and co-pigments were connected by hydrogen bond and π-π stacking interaction. Hydroxycinnamic acids of SIA, FA and p-CA bound with ring B and ring C of C3G, while hydroxybenzoic acids of SYA, VA and GA hardly interacted with ring C. Generally, the protection effect of hydroxycinnamic acids on C3G was better than that of hydroxybenzoic acids, exhibiting stronger hyperchromic effect.

Intermolecular copigmentation between anthocyanidin-3,5-O-diglucosides and three phenolic compounds: Insights from experimental and theoretical studies

Anthocyanidin-3,5-O-diglucosides are the main pigments in red wines made from non-vinifera and hybrid species. In this work, intermolecular copigmentation between three common anthocyanidin-3,5-O-diglucosides and three types of phenolic copigments was systematically investigated in model wine solutions through experimental and theoretical methods. The impact of the sugar moiety at the C5 position of anthocyanin A ring was studied emphatically. Results showed that the anthocyanidin-3,5-O-diglucosides produced much stronger hyperchromic effects compared to the anthocyanidin-3-O-glucosides. Thermodynamic analysis and theoretical calculations suggested higher affinity of the anthocyanidin-3,5-O-diglucosides towards copigments (larger K values and lower ∆G) than corresponding monoglucosidic anthocyanins, mainly due to the enhancement of hydrogen bonds and van der Waals forces resulting from the additional glucose. In conclusion, the results revealed that the glucose at the C5 position of anthocyanin A ring could play a positive role in copigmentation, thus may lead to strong copigmentation effects in these wines.