Anthocyanin Degradation Research Articles

Microencapsulation of blueberry anthocyanins by spray drying with soy protein isolates/high methyl pectin combination: Physicochemical properties, release behavior in vitro and storage stability

Eleven anthocyanins in the blueberry anthocyanins powders (BAP) were identified and quantified by HPLC-DAD-ESI-MS. BAP microcapsules (MBAP) were produced by spray drying using high methyl pectin (HMP) combined with whey protein isolates (WPI) or soy protein isolates (SPI) in different proportions as wall materials. Generally, SPI/HMP combination was more efficient in increasing the encapsulation efficiency and Tg, and in decreasing the particle size and hygroscopicity of the microcapsules than WPI or HMP or WPI/HMP combination. Microcapsules created with 4% SPI + 2% HMP combination (MBAPc), possessed superior anthocyanin release behavior and antioxidant stability to those produced with 4% SPI alone (MBAPs). Both MBAPc and MBAPs had continuous release of anthocyanins throughout the simulated gastrointestinal digestion, and exhibited two first-order kinetics, but MBAPc exhibited higher stability than MBAPs and BAP, because it showed the longest half-life and the lowest anthocyanin degradation rate at 25 °C and 35 °C during 6-months’ storage.

Quality changes of natural dye powder from red leaf amaranth (Alternanthera amoena Voss) during storage

Redleaf amaranth (Alternanthera amoena Voss) can be used as a natural dye because it has high anthocyanin content and is stable on low pH. This research aimed to observe the quality changes of natural dye powder from red leaf amaranth during storage and estimate its shelf life. The production of natural dye powder using a solvent of distilled water+5% citric acid and 15% maltodextrin then dried using a Vacuum Dryer at 60°C temperature for 1 hour. The powder was packed in PP plastic and stored at various temperatures (28, 45, 55 °C). The results showed that the natural dye powder at the beginning of the storage has 4.66% moisture content, 8% yield, 14.43 mg vitamin C/100 g materials, 94.48% solubility, 14.9% total titrated acid, 62.10 mg total anthocyanin/100 g materials and colour at 46.97 °Hue value (red). The higher the storage temperature, the greater the degradation of colour and total anthocyanin. The moisture content of the dye powder increases during storage. The shelf life of natural dye powder at 28°C, 45°C, and 55°C storage temperatures are 97 days, 41 days, and 25 days, respectively. Natural dye powder stored at 28°C has a longer shelf-life than those stored at 45°C and 55°C.

Synergistic effects of Garcinia mangostana and Clitoria ternatea extract mixture on antioxidant activities, colour, and anthocyanin stabilities

The present work determined the antioxidant activities, and colour and anthocyanin stabilities of Garcinia mangostana peel (GMP) and Clitoria ternatea flower (CTF) extract mixtures. The plants were extracted at three different ratios of GMP:CTF at three different extractant pH levels (3.0, 3.5, and 4.0). The highest synergistic effects of ORAC, FRAP, ABTS, and DPPH radical scavenging capacity were observed in the mixture of 25% GMP and 75% CTF (25GMP:75CTF) extracted at pH 3.5. Based on the kinetic degradation of anthocyanin, and the L*, C*, and h° values, 25GMP:75CTF extracted at pH 3.5 exhibited a significantly lower rate constant (-k = 2.27) and higher half-life (t1/2 = 5.09 h) over 100°C, thus indicating the most stable mixture ratio and extractant pH condition of those tested. Therefore, the mixture of GMP and CTF at a ratio of 25:75 and an extractant pH of 3.5 produced the most stable extract with a good synergistic effect.

Metabolome and Transcriptome Analyses of Anthocyanin Accumulation Mechanisms Reveal Metabolite Variations and Key Candidate Genes Involved in the Pigmentation of Prunus tomentosa Thunb. Cherry Fruit.

Prunus tomentosa Thunb. has excellent nutritional, economic, and ornamental values with different fruit color. The red coloration of fruit is determined by anthocyanin pigmentation, which is an attractive trait for consumers. However, the mechanisms underlying fruit color formation in the P. tomentosa cherry are not well understood. In this research, the pigmentation patterns in red-color P. tomentosa (RP) fruit and white-color P. tomentosa (WP) were evaluated. Anthocyanin content in matured RP fruit was significantly abundant compared with WP fruit. Metabolomic profiling revealed that pelargonidin 3-O-glucoside, cyanidin 3-O-rutinoside, and pelargonidin 3-O-rutinoside were the predominant anthocyanin compounds in the RP fruit, while, WP fruit had less anthocyanin compositions and lower level. Then, integrative analyses of transcriptome and metabolome identified 285 significant differentially expressed genes (DEGs) closely related to anthocyanin differentially expressed metabolites (DEMs). Among them, nine genes were involved in anthocyanin biosynthesis, transport and degradation pathway, including four biosynthesis genes (PtPAL1, PtDFR, PtANS, and PtUFGT), two transport genes (PtGST11, PtABC10), and three degradation genes (PtPOD1, PtPOD16, PtPOD73). Transcriptome data and real-time PCR showed that the transcript levels of biosynthesis and transport genes were significantly higher in RP than in WP, especially PtANS, PtUFGT, and PtGST11, suggesting they may play key roles in red-colored fruit formation. Meanwhile, the degradation-related genes PtPOD1/16/73 took on exactly opposite trend, suggesting their potential effects on anthocyanin degradation. These results provide novel insights into color patterns formation mechanisms of cherries fruit, and the candidate key genes identified in anthocyanin biosynthesis, transport and degradation may provide a valuable resource for cherry breeding research in future.

Photoselective Shade Films Mitigate Heat Wave Damage by Reducing Anthocyanin and Flavonol Degradation in Grapevine (Vitis vinifera L.) Berries

Wine grape production is challenged by forecasted increases in air temperature and droughts due to climate change and photoselective overhead shade films are promising tools in hot viticulture areas to overcome climate change related factors. The aim of this study was to evaluate the vulnerability of ‘Cabernet Sauvignon’ grape berries to solar radiation overexposure, optimize shade film use for preserving berry composition. An experiment was conducted for two years with four shade films (D1, D3, D4, D5) with differing solar radiation spectra transmittance and compared to an uncovered control (C0). Integrals for leaf gas exchange and mid-day stem water potential were unaffected by the shade films in both years. At harvest, berry primary metabolites were not affected by treatments applied in either year. Despite precipitation exclusion during the dormant seasons in shaded treatments, and cluster zone temperatures reaching 58°C in C0, yield was not affected. Berry skin anthocyanin and flavonol composition and content were measured by C18 reversed-phase HPLC. In 2020, total skin anthocyanins (mg·berry-1) in the shaded treatments were 27% greater than C0 during berry ripening and at harvest. Conversely, flavonol content in 2020 decreased in partially shaded grapevines compared to C0. Berry flavonoid content in 2021 increased until harvest while flavonol degradation was apparent from veraison to harvest in 2020 across partially shaded and control grapevines. Untreated control showed lower di- to tri-hydroxylated flavonol ratios closer to harvest. Our results provided evidence that overhead partial shading of vineyards mitigate anthocyanin degradation by reducing cluster zone temperatures and is a useful tool in combatting climate change in hot climate regions.

Recent advances on the stability of dietary polyphenols

Recent advances on the stability of dietary polyphenols

Simulated gastrointestinal digestion and colonic fermentation of blue honeysuckle: Phenolic profile and protectivity on ethyl carbamate-induced oxidative damage

Blue honeysuckle (Lonicera caerulea L.) is well-known fruit that belongs to the berries family, and is widely cultivated in China, Russia, and Japan. This study aimed to evaluate the impact of in vitro gastrointestinal digestion followed by gut microbiota fermentation on the phenolic profile of blue honeysuckle as well as the protective effect of digested-blue honeysuckle against ethyl carbamate (EC)-induced oxidative damage. Results of phenolic profile showed that cyanidin-3-O-glucoside was identified as the predominant anthocyanin in blue honeysuckle and was significantly decreased after in vitro digestion. The generation of some metabolites (gallic acid, ferulic acid, and 3,4-dihydroxybenzoic acid) could be attributed to the degradation of chlorogenic acid and anthocyanins. Cellular studies indicated that digested-blue honeysuckle (0.5 and 1 mg/mL) exhibited significant protection against EC-induced cytotoxicity. Digested-blue honeysuckle at a concentration 1.0 mg/mL exhibited significant (p < 0.05) protective effect against EC-induced cytotoxicity in Caco-2 cells via inhibiting ROS and superoxide anion accumulation, attenuating GSH depletion, and inhibiting mitochondrial membrane potential collapse compared to EC-treated group. Blue honeysuckle could be a promising resource for ameliorating EC-induced cellular oxidative damage, which could be an ingredient for functional foods. However, further in vivo studies are recommended to prove the functionality of blue honeysuckle.

Effects of Hot Air Drying on Drying Kinetics and Anthocyanin Degradation of Blood-Flesh Peach.

The purpose of this study was to explore the drying kinetics, effective moisture diffusivity, activation energy, color variation, and the thermal degradation properties of anthocyanins of blood-flesh peach under hot air drying for the first time. The results showed that the hot air-drying process of blood-flesh peach belongs to reduced-speed drying. The Page model could accurately predict the change of moisture ratio of blood-flesh peach. The effective moisture diffusivity during hot air drying of blood-flesh peach was in the range between 1.62 × 10−10 and 2.84 × 10−10 m2/s, and the activation energy was 25.90 kJ/mol. Fresh samples had the highest content (44.61 ± 4.76 mg/100 g) of total monomeric anthocyanins, and it decreased with the increase of drying temperature. Cyanidin-3-O-glucoside and delphinidin-3-O-galactoside were the main anthocyanins of blood-flesh peach as identified and quantified by UPLC-QqQ-MS. Interestingly, during the drying process, the content of cyanidin-3-O-glucoside increased at the beginning, and then decreased. However, the content of delphinidin-3-O-galactoside kept decreasing during the whole drying process. Considering the drying efficiency, fruit color and quality, 70 °C would be a suitable temperature for drying blood-flesh peach. This research will provide beneficial information for understanding the anthocyanin degradation of blood-flesh peach during drying, and guide the production of high-quality dried products.

Effects of process parameters in microwave-assisted extraction on the anthocyanin-enriched extract from Rhodomyrtus tomentosa (Ait.) Hassk and its storage conditions on the kinetic degradation of anthocyanins in the extract

Rhodomyrtus tomentosa (Ait.) Hassk (RTH) is a plant distributed mainly in Southeast Asia that has long been used as a food or a folk remedy for various ailments. Anthocyanins extracted from RTH have received the attention of researchers as well as manufacturers in exploiting the application of this plant for commercial purposes. Several extraction methods have been performed, however, concerns about new extraction methods, extraction conditions as well as stability of anthocyanins during storage are issues that need to be evaluated. In this study, the process of extracting anthocyanins by microwave method and the stability of anthocyanins in RTH extraction were investigated. For the extraction method, the influence of solvent concentration (30–70%), application ratio (10:1–1:1 mL/g), microwave power (100–500W), and time (1–9 min) have been evaluated. A first-order kinetic model was also used to evaluate the variation of anthocyanin content during storage at different conditions, including 5 °C (refrigerator), 30 °C (room temperature), and 45 °C (incubator). The study results showed that the anthocyanin content had the greatest value of 137.54 mg/L when extracted with 50% ethanol solvent with the material/solvent ratio of 1:3 (g/ml) microwave power is 200W for 5 min. The first-order decomposition kinetics model showed that the t1/2 values of the RTH extract were 69.64, 28.66, and 19.8, respectively, for the storage temperatures of 5 °C, 30 °C, and 45 °C, respectively. During storage, anthocyanin content tends to decrease more rapidly under high-temperature conditions. In addition, a close correlation between anthocyanin content and antioxidant capacity was recorded at a high significance level R2 > 0.98.

Effects of different antioxidants combined with high hydrostatic pressure on the color and anthocyanin retention of a blueberry juice blend during storage.

Blueberry juice has been found to undergo severe browning after treatment and cold storage, such as processing by high hydrostatic pressure (HHP) at 550 MPa/10 min/25 °C followed storage at 4 °C for 4 days. This browning may be due to the degradation of anthocyanin (AC) in the berries. Therefore, in this study, gallic acid (GA), ferulic acid (FA), ascorbic acid (VC), citric acid (CA), tea polyphenol (TP) and α-tocopherol (VE) were compared to determine their ability to improve the stability of the AC in HHP-treated blueberry juice. The juice was combined with the six abovementioned antioxidants at different concentrations, then treated by HHP at 550 MPa/10 min/25 °C and stored at 4 °C for 20 days. Thereafter, the pH levels, degrees °Brix, color parameters, total AC content and polyphenol oxidase (PPO) activity of the blueberry juice blend were measured and compared. Gallic acid at 2 g/L was found to be the most effective antioxidant to protect against AC degradation. After storage at 4 °C for 20 days, the AC content of the juice with no added antioxidants had decreased by 62.27% with a PPO relative activity of 50.78%, while the AC content of juice supplemented with 2 g/L GA had decreased by 13.42% with a PPO relative activity of 28.13%. The results of this study, thus, suggest that GA can stabilize the structure of AC in blueberry juice and reduce PPO activity, which may be beneficial in guiding the production of blueberry juice with high AC retention.

Mixed fermentation of Chinese bayberry pomace using yeast, lactic acid bacteria and acetic acid bacteria: Effects on color, phenolics and antioxidant ingredients

Yeast, lactic acid bacteria and acetic acid bacteria were used to ferment Chinese bayberry pomace, and then the effects of mixed fermentation on the quality (color, antioxidant capacity and phenolic compounds) were studied. We found that mixed fermentation could protect the color of beverage and slow down the degradation of anthocyanins. Anthocyanins interact with acetaldehyde, acetic acid and lactic acid produced by lactic acid bacteria and acetic acid bacteria could improve the color of the beverage. However, the action of enzymes would seriously damage the color and aggravate the degradation of anthocyanins. Mixed fermentation promoted the conversion of flavonoids into flavonol aglycones. After mixed fermentation and enzymes action, the type of phenolic acid did not change, but the contents increased. According to the results of DPPH-HPLC, myricetin did not have the ability to scavenging DPPH free radical. Therefore, mixed fermentation could improve the quality of beverage.

Development of a food colorant from Syzygium cumini L. (Skeels) by spray drying.

The objective of the present work was to develop a powder colorant for food use by spray drying from a hydroalcoholic extract of black cherry (Syzygium cumini [L.] Skeels). The content of total solids significantly affected the contents of anthocyanins and total polyphenols, while the air inlet temperature influenced (p≤0.05) the spray drying performance. The optimal drying conditions were 165 °C as air inlet temperature and 25% of total solids, which allowed obtaining a powder colorant with total anthocyanin contents between 4273 and 5070mg/1000g, total polyphenols from 10,142 to 11,184mg/1000g, and a drying yield between 67.14 and 67.7%. The colorant presented 5.65% humidity, 25.2% hygroscopicity, poor fluidity, and high cohesiveness, with a dissolution time of 55s. The degradation of anthocyanins, adjusted to zero-order kinetics, was directly proportional to the increase in temperature and time. The values of the component a* decreased with increasing temperature and time.

Characteristics of anthocyanins in fortified cakes: a promising potent inhibitor of sucrase, α‐glucosidase and lipase

SummaryAnthocyanins are well‐known compounds that can improve gastrointestinal effects and have the potential to be utilised as an ingredient in functional foods. However, the true pharmacological role that they carry out in human body has been largely elusive. Thus, this study was aimed to investigate the inhibitory action of anthocyanins in a cake matrix on intestinal enzymes – α‐glucosidase, sucrase and lipase. Anthocyanin‐rich black rice extract powder (ABREP) was incorporated into cake at the levels of 0, 0.25, 0.5, 1 and 2% of flour weight. The physicochemical properties and in vitro digestibility of the cake, as well as enzyme inhibitory effects of anthocyanins were investigated. Degradation of anthocyanins in the batter occurred up to 68% at the 2% fortification level while the cake matrix asserted a protective effect on the remaining anthocyanins, keeping them by up to 84% after baking. The antioxidant capacity of cakes was increased by nine times when cake was fortified with 2% ABREP. The digestion rate of sucrose was reduced by 4.6 times at a 2% fortification level as compared to the control. Furthermore, cake with 2% ABREP addition showed 150%, 41% and 278% higher inhibitory effects against sucrase, α‐glucosidase and lipase as compared to the one with 0.5% addition, respectively. This study provides an in‐depth understanding of the potential of anthocyanin‐fortified foods for helping people with elevated blood glucose and triglyceride levels.

Chemosensor Strip from Kepok Banana Bracts Extract (Musa paradisiaca L.) for Detection of Tuna Freshness

Anthocyanins as chemosensory compounds for amines have been tested in this study. Because anthocyanins are sensitive to pH changes, while amines have an alkaline nature, they can cause structural changes in anthocyanins, resulting in changes in the color of anthocyanins. The source of anthocyanins was the Kepok banana bracts (Musa paradisiaca L.), which were extracted using a mixture of ethanol:HCl 0.15% (3:2). The types of anthocyanin compounds were characterized using a UV-Vis spectrophotometer. The anthocyanin content obtained varied from 1.26 mg/100 g to 5.08 mg/100 g. The type of anthocyanin in the Kepok banana bracts was found as a cyanidin-3-rutinoside with maximum absorption at 513 nm at pH 1. The color of anthocyanin extract varied with changes in pH; it turned red in acid and faded in neutral solutions. The green color in the alkaline solution changes to brownish-yellow was associated with anthocyanin degradation. The color change at different pH indicates that banana bracts are regarded as a potential chemosensory compound to detect tuna freshness. The chemosensor was applied to a cellulose-based strip and exhibited a color change that corresponded to the increase in pH and was comparable to the results of the pH meter measurement. The structural changes of anthocyanin before and after the tuna freshness test were identified by the FTIR-ATR, indicating a change in the anthocyanin structure. Tuna freshness began to diminish after being stored for 12 and 24 hours at room temperature, marked by a color change of the paper strip to colorless and blackish gray.

Color fading in lotus (Nelumbo nucifera) petals is manipulated both by anthocyanin biosynthesis reduction and active degradation

Flower color is a key trait that determines the ornamental quality of aquatic lotus (Nelumbo nucifera). Color fading significantly decreases the ornamental value of lotus flowers. However, the molecular mechanism underlying lotus petal discoloration remains largely unknown. Here, the anthocyanin content and global transcriptional profiling of lotus petals of cultivar ‘Qiusanse’ in four developmental stages were analyzed. Five anthocyanin components were detected, and the total anthocyanin content decreased as the petal color changed from red to nearly white. Moreover, the malondialdehyde (MDA) content and peroxidase (POD) activity increased during color fading. RNA-seq analysis revealed a total of 4,092 differentially expressed genes (DEGs) between petal developmental stages. Notably, oxidoreductase and hydrolase activity related genes were overrepresented in DEGs. The expression pattern of key anthocyanin biosynthesis genes including, CHS, F3H, ANS, UFGT, and transcription factor regulators, including MYBs, WRKYs and bHLHs were correlated with anthocyanin accumulation. Interestingly, DEGs associated with anthocyanin degradation and vacuolar pH regulation, including peroxidase, proton pumps regulators such as WRKY3 and MYB5-like, were significantly upregulated during the late stages of flowering. This study reveals for the first time the transcriptional dynamics during lotus petal discoloration. Our results suggest the involvement of anthocyanin biosynthesis repressors and degrading genes as well as pH regulators in controlling color fading of lotus petals. The study also provides valuable information and candidate genes for improving the lotus flower color.

Study of anthocyanins as related to stability of infrared freeze-dried rose flower using novel ultrasound pretreatment

The present study was undertaken to determine the mechanism of anthocyanin content (ACNs) and related stability of infrared freeze-dried rose flowers using novel ultrasound pretreatments (20 kHz and 45 kHz for 5, 10 and 15 min). Additionally, the impact of such processing on peroxidase, polyphenol oxidase, color, moisture, total phenolic, total flavonoid, anthocyanins degradation during storage and chemical structure of infrared freeze-dried flowers was evaluated quantitatively. Peroxidase in rose flowers was effectively inactivated while polyphenol oxidase was activated very slowly (85, 95.67, 87.33, 77.67, 93, 98, 90.67%) by ultrasound pretreatment at 45 kHz and 20 kHz for 5, 10 and 15 min, respectively. The TPC and TFC of dried rose flowers pretreated by 45 kHz ultrasound (US) was also higher than that of dried roses pretreated by 20 kHz US. Moreover, US at 45 kHz was beneficial for the retention of color and anthocyanins of roses after infrared freeze-drying. In addition, US treatment at 45 kHz for 10 min resulted the lowest ACNs degradation rate during storage. These results demonstrate that US treatment at 45 kHz is a potential technique for improving the stability of anthocyanins during its processing and storage.

Preservation of color and nutrients in anthocyanin‐rich edible flowers: Progress of new extraction and processing techniques

In recent years, a new trend in the food industry is the use of flowers in food production. Although currently consumed on a relatively small scale around the world, edible flowers have been a source of nutritional diets since ancient times due to their aesthetic appeal and desirable aroma. The importance of color acceptability and the need to meet and attract more consumers to market have led to the development of new pigments for industrial products. The stability of anthocyanin is influenced by a number of factors such as pH, temperature, oxygen as well as the presence of co-pigments and metallic ions. It can also easily degraded by oxidase. Several preservation methods can improve the stability of anthocyanin, phytochemicals, nutrients and other functional properties of edible flowers. This article comprehensively reviewed the recently developed processing and preservation technologies for color retention, anthocyanin degradation, and anthocyanin-related enzyme inactivation as well as various methodologies for the extraction of anthocyanins from edible flowers. It should be noted that not all flowers are safe to consume due to potential presence of natural toxins. Practical applications The synergistic effect of novel treatments could maintain anthocyanins degradation, color, nutrients, and bioactive compounds as well as the novel extraction techniques were also expressed to extract the anthocyanins of edible flowers. The anthocyanins pigments have been traditionally used as a natural colorant nowadays. Besides being used as natural colorants, some of the anthocyanin-rich flowers and fruits have been used as medicine to treat various diseases.

Delineating the behavior of Berberis anthocyanin/β-cyclodextrin inclusion complex in vitro: A molecular dynamics approach

Inclusion complex (ICBA) of Berberis lycium anthocyanins (BA) with β-cyclodextrin (β-CD) was prepared by freeze drying technique at stoichiometric equimolar ratio. Spectroscopic and microscopic analyses confirmed successful inclusion of the guest (BA) inside host (β-CD) cavities. In dissolution study, 72.4% anthocyanin was released from ICBA in 90 min, unlike 98.4% in case of BA. Encapsulation with β-CD provided improved thermal stability of anthocyanins as half-lives were increased. Activation energy required for the thermal degradation of anthocyanins was found to be higher in ICBA (42.42 kJ mol−1) than BA (35.86 kJ mol−1). Although similar bioaccessibility of anthocyanin was observed in both ICBA and purified crystals, β-CD provided better thermal stability and regulated the release of anthocyanins. While predicting the role of non-bonding forces between the selected anthocyanins and β-CD, molecular docking study revealed that delphinidin-3-glucoside (d3g) and β-CD complex was thermodynamically more stable than cyanidin-3-glucoside (c3g) complex. Molecular dynamics studies and quantum chemical calculations using density function theory provided an insight to explain the behavior of anthocyanins (in aqueous environment) within the inclusion complex cavity. Result concluded that β-CD is an appropriate host for the stability enhancement of anthocyanins.

Thermal Stability and Inhibitory Action of Red Grape Skin Phytochemicals against Enzymes Associated with Metabolic Syndrome

The present study focuses on heat-induced structural changes and the degradation kinetics of phytochemicals and antioxidant activity of red grape skin extract. The thermal degradation of anthocyanins, flavonoids, polyphenols, and antioxidant activity followed a first-order kinetic model, increasing with temperature due to the intensification of the degradation process. The activation energy (Ea) highlighted this phenomenon. Likewise, the kinetic and thermodynamic parameters certified the irreversible degradation of the bioactive compounds from the skin of the Băbească neagră grape variety. Both temperature and duration of heating had a significant impact on the content of bioactive compounds. In addition, the red grape skin extract inhibited certain enzymes such as α-amylase, α-glucosidase, lipase, and lipoxygenase, which are associated with metabolic syndrome and inflammation. Further knowledge on the possible inhibition mechanisms exerted by the major anthocyanins found in red grape skin extract on the metabolic syndrome-associated enzymes was gathered upon running molecular docking tests. Detailed analysis of the resulting molecular models revealed that malvidin 3-O-glucoside binds in the vicinity of the catalytic site of α-amylase and lipase, whereas no direct contact with catalytic amino acids was identified in the case of α-glucosidase and lipoxygenase.

A New Insight into the Degradation of Anthocyanins: Reversible versus the Irreversible Chemical Processes.

The kinetics and thermodynamics of the pH-dependent reversible and irreversible processes leading to color fading of pelargonidin-3-O-glucoside, peonidin-3-O-glucoside, malvidin-3-O-glucoside, and cyanidin-3-O-glucoside dyes in aqueous solutions are reported. Following the addition of base to the flavylium cation, the quinoidal bases disappear by three distinct steps: (i) in an acidic medium by a biexponential process, in which the faster step is controlled by the hydration reaction and the slower one by cis-trans isomerization; the degradation process occurs essentially from the anionic quinoidal base; (ii) in a basic medium (pH > 9.5), in which the disappearance of the anionic bases is monoexponential, with the rate proportional to the hydroxyl concentration (hydroxyl attack), leading to anionic chalcones (cis and trans) at equilibrium─the slower degradation step occurs from the di- and trianionic chalcones; and (iii) in the pH region circa 7.7 < pH < 9.5, in which hydration and hydroxyl attacks are much slower than anionic quinoidal base degradation (which is the rate-controlling step) and the equilibrium cannot be attained.