Adsorption Of Anthocyanins Research Articles

Adsorption characteristics of modified bentonites for purification of anthocyanin from saffron tepal

AbstractIn this study, anthocyanin was extracted from saffron tepals utilizing the ultrasound‐assisted extraction method. The adsorbents of raw bentonite (RB), acid activation of bentonite (AA) thermal activation of bentonite (TA), and acid and thermal activation of bentonite (ATA) were employed to separate anthocyanin from solution. The influence of the operating parameters was evaluated. The isotherm study demonstrated that anthocyanin adsorption on adsorbents could be fitted better by the Langmuir equation than the Freundlich equation. A good agreement between the predicted consequences of the pseudo‐second‐order model and empirical data was provided. Thermodynamic parameters indicated that anthocyanin was adsorbed in an exothermic and physical process. Findings presented that the best adsorption performance of anthocyanin related to ATA with 2.25 mg/g adsorption capacity which was more than 1.55, 1.75, 1.88 mg/g for RB, AA, and TA, respectively. It was due mainly to the increased surface area by both thermal and acid activation of raw bentonite.

Fabricating a high-loading smart film to monitor pork freshness via adsorption of anthocyanins on simultaneously etched, anionized and bleached wood cell wall

In this paper, wood cell walls were simultaneously roughened, carboxylated, and bleached via NaOH/H2O2 treatment and roughened-poplar film (RPF) was obtained. Compared with the untreated film, the carboxyl group content increased 8 times to 1.92 mmol/g, and the pore growth rate reached 11.24%. Afterwards, a pH-indicator wood film (CTA-RPF) was prepared by self-adsorption of anthocyanins on RPF. It rapidly changed from purple to green within 7 s in 0.25 mL of ammonia at 53% RH and the initial color could restore in the air. When anthocyanins adsorption capacity reached 1.95 mg/g, only 0.36 cm2 of the film could accurately indicate the quality change of 300 g pork. Currently, CTA-RPF is the smallest smart film that can track the maximum mass of pork after comparing with other researches, therefore, promising to be used as a smart indicator label to track the freshness of pork in real market circulation.

Adsorption and desorption process for high recovery and purification of anthocyanins from (Clitoria ternatea L) using macroporous resins

The intense coloration of the petals of the butterfly bean flowers (Clitoria Ternatea L.) is attributed to high content of anthocyanins, which are considered as an antioxidant phytochemicals that have many health benefits. In this context, it is so important to implement a new method for the separation and purification of phenolic compounds. Therefore, the objective of this work was to evaluate the adsorption and desorption behavior of anthocyanins extracted from the petals of the butterfly bean flowers, using six different macroporous adsorption resins (XAD 2, XAD 4, XAD 7HP, DAX 8. XAD 1180 N and XAD 16), and to identify the best type of resin for anthocyains recovery from butterfly bean flowers extract. The XAD7HP and DAX8 resins showed high adsorption capacity, (248.55 ± 8.8 mg/g) and (228.84 ± 16.9 mg/g) at pH 5, and the highest recovery values for anthocyanins; (75.66 ± 1.1%) and (52.64 ± 1.2%), respectively. The Langmuir model described better the adsorption isotherm process on DAX 8, in turn, the experimental data of equilibrium were better fitted by Freundlich model for isotherm adsorption of anthocyanin on XAD7HP resin. The pseudo-second order model was the best to fit the experimental data of the adsorption kinetics at the different temperatures used. Both resins XAD 7HP and DAX 8 presented high recovery of anthocyanin, comparing with conventional extracted methods the purified anthocyanin using XAD 7HP and DAX 8 can be used as biological compounds with more purity for food and pharmaceutical applications.

Wine Barrel Biofilm as a Source of Yeasts with Non-Conventional Properties.

This study investigated the main microbial groups characterizing the interior surface of oak barrels from different years (1890, 1895, 1920, 1975, 2008) used in the production of vino cotto. The yeasts were characterized for the following properties: γ-aminobutyric acid (GABA) production, antioxidant activity, air-liquid interfacial biofilm formation, and anthocyanin adsorption capacity. Community-level physiological profile analysis revealed that the microbial communities inside the barrels used the tested carbon sources in different manners. The following yeast species were identified: Millerozyma farinosa, Zygosaccharomyces bisporus, Wickerhamiella versatilis, Zygosaccharomyces bailii, Starmerella lactis-condensi, and Zygosaccharomyces rouxii. All the strains were able to produce GABA, and S. lactis-condensi, Z. bisporus and Z. rouxii were the highest producers (more than 600 mg/L). The Z. rouxii and Z. bailii strains showed the highest antioxidant activity. Only seven strains out of ten M. farinosa formed air-liquid interfacial biofilm. None of the M. farinosa strains adsorbed anthocyanins on their cell wall. The other strains adsorbed anthocyanins in a strain-dependent way, and the highest adsorption was observed for the W. versatilis strains. The yeasts isolated in this study could be used to increase the functional properties and the quality of fermented foods and beverages.

Enhanced stability of anthocyanins by cyclodextrin–metal organic frameworks: Encapsulation mechanism and application as protecting agent for grape preservation

Anthocyanins are promising naturally occurring food preservatives for enhancing the quality of food products due to their excellent antioxidant properties. However, their low stability hinders their food packaging application. Here, we propose a facile strategy to achieve the improved stability of anthocyanins encapsulated in γ-cyclodextrin metal-organic frameworks (CD-MOFs) with an in-depth exploration of their structure–property relationships. The adsorbed anthocyanins in CD-MOFs are stabilized by multiple cooperative non-covalent interactions including hydrogen bonding and van der Waals (vdW) interactions as demonstrated by density functional theory (DFT) calculations and spectroscopy analysis. Particularly, by ion-exchange of acetate ions into the pores of CD-MOFs, the resulting CD-MOFs (CD-MOF_OAc) shows a higher anthocyanins adsorption rate with a maximum loading capacity of 83.7 % at 1 min. Besides, CD-MOF_OAc possesses the more effective protecting effect on anthocyanins with at least two-fold enhancement of stability in comparison of free anthocyanins under heating and light irradiation. The anthocyanins encapsulated CD-MOFs films for fruit freshness was validated by the Kyoho experiment. This novel encapsulation system provides a new possibility for the potential use of CD-MOFs as the encapsulating material for anthocyanins in fruit preservation.

Facile Fabrication of Anthocyanin-Nanocellulose Hydrogel Indicator Label for Intelligent Evaluation of Minced Pork Freshness.

In order to develop a reliable and rapid method for meat freshness detection, nanocellulose (TOCNF) prepared via the TEMPO (2,2,6,6-tetramethylpiperidine oxidation) oxidation method was used as raw material to prepare hydrogels using Zn2+ coordination and binding. Physicochemical properties such as water absorption and porosity were analyzed. It was further used to select suitable hydrogels for the preparation of indication labels after anthocyanin adsorption, and it was applied in the freshness detection of fresh minced pork. Five percent TOCNF (w/w) aqueous solution was homogenized by high shear for 4 min, and 20% (w/w) zinc chloride solution was added to it, so that the concentration of zinc ions could reach 0.25 mol/L. After standing for 24 h, the hydrogel was obtained with good water absorption and a porous three-dimensional network structure. The activation energies of volatile base nitrogen (TVBN) and anthocyanin indicating label color changes were 59.231 kJ/mol and 69.453 kJ/mol, respectively. The difference between the two is within 25 kJ/mol, so the prepared indicator label can accurately visualize the shelf life of fresh pork.

In English

In the last decades there has been an increased interest of researchers in the obtaining anthocyanins from available and low–cost plant materials, not only as natural food dyes but also for pharmaceutical products. Among plant sources of anthocyanins chokeberries and elderberries have attracted the interest of consumers due to abundant anthocyanin contents. In this study, adsorption equilibrium and thermodynamics of anthocyanins from chokeberry and elderberry extracts by fibrous cation exchanger FIBAN K–1 were investigated. The anthocyanin extracts were obtained by macerated in 0.1 M HCl under the follow extraction parameters: solid-liquid ratio = 1:2 at 293 K for 24 h. The total anthocyanin content in the extracts was determined by pH-differential method. Adsorption experiments were carried out under static conditions, shaking mixtures of anthocyanin extracts of the berries with FIBAN K–1. The adsorption isotherms were of L-type according to the classification of Giles. The adsorption capacity of FIBAN K– 1 for the chokeberry and elderberry anthocyanins increased as the temperature increased from 293 to 313 K. The Langmuir, Freundlich, and Temkin adsorption models were used to describe the experimental adsorption isotherms. These models had a good agreement with the experimental data for adsorption of the anthocyanins, but the Langmuir model was the most favorable model for studying the adsorption equilibrium of the chokeberry and elderberry anthocyanins on FIBAN K–1. Thermodynamic parameters of the anthocyanin adsorption, such as DG°, DH°, and DS° were calculated. The ∆G° values were negative, thus indicating that the adsorption of the chokeberry and elderberry anthocyanins on FIBAN K-1 was spontaneous and favorable process under the experimental conditions. The decrease of the ΔG° values with increasing temperature shows that adsorption is more favorable at high temperature. The ∆H°values were positive for the anthocyanins of both kind of berries, which indicates the adsorption was an endothermic reaction. The ∆S°values were positive, which means that the anthocyanins in the aqueous phase are more organized than those in the adsorbent-liquid interface.

Intelligent labels manufactured by thermo-compression using starch and natural biohybrid based

This work aims to develop intelligent labels based on cassava starch and biohybrid pigments by thermo-compression. The biohybrid pigment (BH) was developed by the adsorption of anthocyanins (ACNs) extracted from the jambolan fruit (Syzygium cumini L.) into montmorillonite (Mt) in order to improve its stability. The effect of the addition of biohybrid on the physicochemical properties of the thermo-pressed starch labels was evaluated. ACNs from jambolan extract show a visible pH-dependent color-changing ability at pH 1 - 12, and the adsorption did not modify the color property. The intelligent labels presented a homogeneous surface, and the BH was well dispersed in the starch matrix. The presence of BH increased the solubility in the water of starch labels. Chemical structure characterization revealed that the BH interacted with starch matrices through hydrogen bonds. Furthermore, the thermal stability of starch labels increased with the presence of BH. Hence, the purple color of intelligent labels was preserved at high temperatures. Finally, labels containing BH show visible changes from purple to a blue color when exposed to ammonia vapor, which simulates the degradation of meat products. Thus, the label content jambolan pigments will be used to control meat deterioration.

Separation of anthocyanin from roselle extract by cationic nano-rode ZIF-8 constructed using removable template

Anthocyanins are biological antioxidants useful for treatment of cancer, diabetes, cardiovascular and neurodegenerative diseases. The point of innovation in the current approach is to study the affinity of super-structured ZIF-8 in separation of anthocyanin from roselle extract. Nano-rode crystalline ZIF-8 was synthesized by crystal growth technique in the presence of cellulose fibers as removable templates. ZIF-8 was growth over the fibers-based template to produce C-ZIF-8, M-ZIF-8 and B-ZIF-8.The rode size of the obtained ZIF-8 was dependent on the type of the used fiber template. Langmuir maximum capacity for B-ZIF-8 was reached 517.31 mg/g. The anthocyanin adsorption onto ZIF-8 was carried out physically through deposition within pores and chemically through the electrostatic interaction between ZIF-8 and anthocyanin. After 5 recycles, the adsorption capacity for B-ZIF-8 was marginally diminished from 466 mg/g to 440 mg/g. In desorption process, 91–99% from the adsorbed anthocyanin was separated from ZIFs-8 within 60 min.

Modeling of anthocyanins adsorption onto chitosan films: An approach using the pore volume and surface diffusion model

The use of smart packaging is a global trend, and several works are being reported in this sense. Special attention is given to biodegradable materials like chitosan and natural pigments like anthocyanins. For example, previous studies report that it is possible to produce smart packaging by extracting anthocyanins from red cabbage and adsorbing it into chitosan films. This work elucidates for the first time the mass transfer aspects in the anthocyanins adsorption on chitosan films (CFS). Anthocyanins were extracted from red cabbage and subsequently adsorbed from the leach liquor using chitosan films. The Freundlich model well represented the adsorption isotherms of anthocyanins on CFS. In addition, the PVSDM (pore volume and surface diffusion model) model was implemented to represent the adsorption data and to elucidate the mass transfer. This model was suitable to represent the adsorption data, with a coefficient of determination (R2) higher than 0.95 and an average relative error (ARE) lower than 2.00%. The surface diffusion coefficient values (DS) ranged from 3.70 × 10−10 cm2 s−1 to 1.16 × 10−9 cm2 s−1. The external mass transfer coefficient (kF) was in the range of 10−2 cm s−1. Finally, the Biot number (Bi) revealed that mechanisms inside the particle controlled the anthocyanin's adsorption onto CFS.

Encapsulation of roselle anthocyanins in blank alginate beads by adsorption and control of anthocyanin release in beverage by coatings with different molecular weight chitosan

In this study, the encapsulation of roselle anthocyanins was improved by immersing blank alginate beads in concentrated anthocyanin extracts. When increasing the alginate concentration (1–3%) and the anthocyanin concentration in the soaking solution (0.1–1.0 g/L), the phenolics, flavonoids, and anthocyanins gradually adsorbed to the matrix over time and peaked at 84–108 hr, leading to higher antioxidant activities. Before added to an acidic beverage, 3% alginate hydrogels soaked in solution of 1.0 g/L after 84 hr were coated using two types of chitosan with low and medium molecular weight. The results showed that low-molecular weight chitosan was superior to medium-molecular weight chitosan in limiting the diffusion of anthocyanins into beverage. The release rates of anthocyanins into beverage were in descending order: control > medium-molecular weight chitosan > low-molecular weight chitosan, as illustrated by the time required for anthocyanins to reach an equilibrium state being 1, 150, and more than 400 hr, respectively. Novelty impact statement Blank alginate gels were soaked in the concentrated roselle solution for anthocyanin adsorption. The antioxidant contents and activities increased at higher alginate and anthocyanin concentrations in the soaking solution and peaked at 84–104 hr. Low-molecular weight chitosan coating reduced the rate of anthocyanin release from beads into acidic beverages.

Impact of the variety on the adsorption of anthocyanins and tannins on grape flesh cell walls.

During winemaking, after extraction from the skins, anthocyanins and tannins adsorb onto the pulp flesh cell walls. The present study aimed to quantify the amounts adsorbed and their impact on wine composition, the impact of variety and ethanol on adsorption, and whether the presence of anthocyanins plays a role and impacts tannin adsorption. Anthocyanin and tannin fractions obtained by mimicking winemaking conditions were mixed with fresh flesh cell walls of two varieties: Carignan and Grenache. Adsorption isotherms were measured. Adsorption of tannins was higher with Carignan than with Grenache and decreased when the ethanol content increased. In comparison, anthocyanins were adsorbed in small amounts, and their mixing with tannins had no impact on their adsorption. The differences were related to differences in pulp cell wall composition, particularly in terms of extensins and arabinans. Adsorption of tannins, which can reach 50% of the initial amount, depends on the pulp cell wall composition. This needs to be investigated further. © 2021 Society of Chemical Industry.

Discovering the Influence of Microorganisms on Wine Color.

Flavor, composition and quality of wine are influenced by microorganisms present on the grapevine surface which are transferred to the must during vinification. The microbiota is highly variable with a prevalence of non-Saccharomyces yeasts, whereas Saccharomyces cerevisiae is present at low number. For wine production an essential step is the fermentation carried out by different starter cultures of S. cerevisiae alone or in mixed fermentation with non-Saccharomyces species that produce wines with significant differences in chemical composition. During vinification wine color can be influenced by yeasts interacting with anthocyanin. Yeasts can influence wine phenolic composition in different manners: direct interactions—cell wall adsorption or enzyme activities—and/or indirectly—production of primary and secondary metabolites and fermentation products. Some of these characteristics are heritable trait in yeast and/or can be strain dependent. For this reason, the stability, aroma, and color of wines depend on strain/strains used during must fermentation. Saccharomyces cerevisiae or non-Saccharomyces can produce metabolites reacting with anthocyanins and favor the formation of vitisin A and B type pyranoanthocyanins, contributing to color stability. In addition, yeasts affect the intensity and tonality of wine color by the action of β-glycosidase on anthocyanins or anthocyanidase enzymes or by the pigments adsorption on the yeast cell wall. These activities are strain dependent and are characterized by a great inter-species variability. Therefore, they should be considered a target for yeast strain selection and considered during the development of tailored mixed fermentations to improve wine production. In addition, some lactic acid bacteria seem to influence the color of red wines affecting anthocyanins’ profile. In fact, the increase of the pH or the ability to degrade pyruvic acid and acetaldehyde, as well as anthocyanin adsorption by bacterial cells are responsible for color loss during malolactic fermentation. Lactic acid bacteria show different adsorption capacity probably because of the variable composition of the cell walls. The aim of this review is to offer a critical overview of the roles played by wine microorganisms in the definition of intensity and tonality of wines’ color.

Brown rice proteins as delivery system of phenolic and volatile compounds of raspberry juice

SummaryDevelopment of novel food ingredients with health benefits as well as desired sensory attributes is of great importance for food industry. For that purpose, complexes (BRP/R) between brown rice proteins (amounts varied; 2%, 6% and 10%) and raspberry juice were prepared. Obtained complexes were evaluated for the amount of volatile compounds, phenolic content, anthocyanin content and antioxidant activity. Those parameters depended on proteins amount. The highest adsorption of total phenolics and anthocyanins (18.18 mg g−1 and 4.59 mg g−1, respectively) was observed on complexes obtained with the lowest amount of proteins (2%). Regarding volatiles, dominant flavour note in raspberry juice was berry (40% of overall flavour), followed by citrus and woody notes (each around 18%), while dominant flavour note on complexes was citrus note (60%) followed by green note (15%). These results suggest an efficient plant‐based approach to produce value‐added protein‐based complexes with possible utility as food colourant and flavouring.

Synthesis of porous starch microgels for the encapsulation, delivery and stabilization of anthocyanins

A novel pH/salt-responsive porous microgel was developed from hydrolyzed oxidized starch for the encapsulation, delivery, and stabilization of anthocyanins. To synthesize this microgel, native corn starch was modified by sequential TEMPO oxidation and glucoamylase hydrolysis, using trisodium phosphate (STMP) as a cross-linker. The morphology, structure, and physical properties of the modified starch samples and microgels were characterized by SEM, ATR-FTIR, and particle size analyses, as well as by zeta-potential measurements. The obtained results indicate that compared to the oxidized microgels, the porous microgels exhibit higher capacity of anthocyanin loading and slower release. A pH of 3 is least favorable for the loading of anthocyanins into the microgels and 22.7% of the encapsulated anthocyanins are released from oxidized microgels, compared to 10.4% released from porous microgels. In addition, the porous microgels enhance the stability of anthocyanins, which facilitates storage. The residual rate of anthocyanins encapsulated in porous microgels is around 31%, whereas that of compounds in oxidized microgels approaches 18% after 30 d of storage. • A novel pH/salt-responsive porous microgel was developed from hydrolyzed oxidized starch. • The adsorption, delivery and stabilization of anthocyanins were investigated. • The porous microgels exhibit higher capacity of anthocyanin loading and slower release.

Understanding of Adsorption and Desorption Mechanisms of Anthocyanins and Proanthocyanidins on Heterogeneous and Homogeneous Cation-Exchange Membranes.

The presence of membrane fouling is the main drawback in membrane processes, and it is related to the premature use and high cost for the replacement of membranes. Polyphenols in cranberry juice are associated with ion-exchange membrane fouling, and it results in a loss of these beneficial compounds in the juice when treated by membrane processes such as electrodialysis. In the present work, four heterogeneous or pseudohomogeneous cation-exchange membranes (CSE-fg, MK-40, CEM Type-II, and CJMC-5), different in terms of the polymer matrix (aromatic, aliphatic), exchange capacity, size, and location of meso and macropores, were studied to understand the impact of the membrane structure and physico-chemical properties on adsorption and desorption of phenolic compounds (anthocyanins and proanthocyanidins) from cranberry juice. It appeared from these results that MK-40, CEM Type-II, and CSE-fg were more prone to fouling due to their high ion-exchange capacity, their thickness, and the presence of meso and macropores in their structure. Indeed, electrostatic interactions occurred between fixed groups of membranes and polyphenolic ions. Desorption of the entire membrane and cryogenic grinding with pH adjusted to 10 allowed a better recovery of anthocyanins and proanthocyanidins (PACs), respectively, since hydroxide ions competed with polyphenols and membrane that induced desorption of polyphenols. In the future, this new knowledge will become the basis for a more sensible choice of membranes and for the development of protocols for extending their life cycle.

Adsorption of Anthocyanins by Cation and Anion Exchange Resins with Aromatic and Aliphatic Polymer Matrices.

This study examines the mechanisms of adsorption of anthocyanins from model aqueous solutions at pH values of 3, 6, and 9 by ion-exchange resins making the main component of heterogeneous ion-exchange membranes. This is the first report demonstrating that the pH of the internal solution of a KU-2-8 aromatic cation-exchange resin is 2-3 units lower than the pH of the external bathing anthocyanin-containing solution, and the pH of the internal solution of some anion-exchange resins with an aromatic (AV-17-8, AV-17-2P) or aliphatic (EDE-10P) matrix is 2–4 units higher than the pH of the external solution. This pH shift is caused by the Donnan exclusion of hydroxyl ions (in the KU-2-8 resin) or protons (in the AV-17-8, AV-17-2P, and EDE-10P resins). The most significant pH shift is observed for the EDE-10P resin, which has the highest ion-exchange capacity causing the highest Donnan exclusion. Due to the pH shift, the electric charge of anthocyanin inside an ion-exchange resin differs from its charge in the external solution. At pH 6, the external solution contains uncharged anthocyanin molecules. However, in the AV-17-8 and AV-17-2P resins, the anthocyanins are present as singly charged anions, while in the EDE-10P resin, they are in the form of doubly charged anions. Due to the electrostatic interactions of these anions with the positively charged fixed groups of anion-exchange resins, the adsorption capacities of AV-17-8, AV-17-2P, and EDE-10P were higher than expected. It was established that the electrostatic interactions of anthocyanins with the charged fixed groups increase the adsorption capacity of the aromatic resin by a factor of 1.8–2.5 compared to the adsorption caused by the π–π (stacking) interactions. These results provide new insights into the fouling mechanism of ion-exchange materials by polyphenols; they can help develop strategies for membrane cleaning and for extracting anthocyanins from juices and wine using ion-exchange resins and membranes.

The impact of Saccharomyces and non-Saccharomyces yeasts on wine colour: A laboratory study of vinylphenolic pyranoanthocyanin formation and anthocyanin cell wall adsorption

Wine fermentation is a complex process driven by yeasts, which influence the key properties of wine quality: aroma, flavour and colour. We investigated 95 different Saccharomyces and non-Saccharomyces strains for their impact on wine colour through the synthesis of the stable pigments, pyranoanthocyanins. All strains were screened for their hydroxycinnamate decarboxylase (HCDC) activity that varied from 0.0% to 91.1%. Eight strains that showed more than 40% HCDC activity were further studied for vinylphenolic pyranoanthocyanin formation. Fermentations were carried out in deep well microtiter plates using synthetic grape must containing Pinot Noir skin extract supplemented with p-coumaric acid. Two strains Pichia guilliermondii ZIM624 and Wickerhamomyces anomalus S138 synthesized vinylphenolic pyranoanthocyanins in the highest concentration in single culture fermentations, 40.2 and 38.5 mg L−1, respectively. The highest produced concentration of vinylphenolic pyranoanthocyanins in co-inoculation experiments was 16.4 mg L−1 compared to 29.8 mg L−1 in sequential fermentations. For the first time, S. paradoxus strains were assessed for pyranoanthocyanin formation. Selected strains were also tested as mono-cultures for adsorption of anthocyanins on yeast cell walls and all strains showed anthocyanin and pyranoanthocyanin adsorption to their cell wall with Metschnikowia reukafii ZIM2019 showing the highest adsorbing capability (9.1%).

Adsorption and biotransformation of anthocyanin glucosides and quercetin glycosides by Oenococcus oeni and Lactobacillus plantarum in model wine solution.

Anthocyanins and flavonols play a significant role in contributing to wine color and mouthfeel, and the interaction of malolactic fermentation with these compounds is not well known. Here we investigated the adsorption of these compounds by Oenococcus oeni and Lactobacillus plantarum. Delphinidin-3-glucoside (D3G) was adsorbed the most, followed by malvidin-3-glucoside (M3G) and peonidin-3-glucoside (P3G) for both the bacterial species, while flavonols were not adsorbed. An increase in β-glycosidase activity suggested that this enzyme breaks down the anthocyanin glucosides, providing sugars for growth. An average decline of approximately 65% in enzyme activity in the presence of substantial residual sugar was observed. The specific metabolic rates were found to be dependent on the class of anthocyanin and species / strain of the bacteria. Selective adsorption of anthocyanins and not the flavonol glycosides suggest that electrostatic interactions mediate the adsorption. Further, a breakdown of anthocyanins resulted in phloroglucinol aldehyde from the flavonoid A-ring and corresponding phenolic acids from the B-ring, i.e., gallic acid for D3G, syringic acid for M3G, and vanillic acid for P3G. The breakdown and adsorption of the anthocyanin glucosides can help explain the color loss and aroma changes, such as the appearance of syringic and vanillic acid, associated with malolactic fermentation. © 2019 Society of Chemical Industry.

Equation for the Dynamics of First-Order Irreversible Sorption, Based on the Adsorption of Anthocyanins by Bentonite Clay

A new equation is proposed to replace the popular Lagergren equation describing the irreversible sorption of substances by a first-order reaction kinetics. The proposed equation considers the free surface of the sorbent. According to the equation, parameter $$\ln \left( {\frac{{{{c}_{\tau }}}}{{{{c}_{\tau }} - {{c}_{{{\text{fin}}}}}}}} \right)$$ is related linearly to the time from the beginning of sorption, where cτ and cfin are the current and final (when the surface is completely filled) sorbate concentrations, respectively. It is shown that the equation effectively describes the dynamics of sorption of anthocyanins of different structures with no exclusion of the initial experimental points, which is typical when using the Lagergren equation.