Search

This study aims to monitor composition changes in an anthocyanin-rich beverage during storage by the means of UV-VIS measurements associated with a multi-curve resolution procedure. Hibiscus sabdariffa extract was stored at 37 °C for 50 days and UV-VIS spectra were measured on the extract and the fractions of the extract every 5 days. MCR was carried out in two steps, first with the fraction and then the extract spectra. The results enabled the main polyphenols initially present to be identified, anthocyanins and chlorogenic acid, but also found the nature of the main degradation products: the polymers from anthocyanin condensation and scission products. In addition, comparison with HPLC analysis results showed that the MCR procedure recovered the correct shapes of the concentration profiles particularly of anthocyanin and polymer kinetics during storage. This work gives perspective for the use of a rapid and efficient technique to monitor pigment-rich beverage processing or storage., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Effect of oxygen, polyphenols and metals was studied on degradation of delphinidin and cyanidin 3-O-sambubioside of Hibiscus sabdariffa L. Experiments were conducted on aqueous extracts degassed or not, an isolated polyphenolic fraction and extract-like model media, allowing the impact of the different constituents to be decoupled. All solutions were stored for 2months at 37°C. Anthocyanin and their degradation compounds were regularly HPLC-DAD-analyzed. Oxygen concentration did not impact the anthocyanin degradation rate. Degradation rate of delphinidin 3-O-sambubioside increased 6-fold when mixed with iron from 1 to 13mg.kg -1 but decreased with chlorogenic and gallic acids. Degradation rate of cyanidin 3-O-sambubioside was not affected by polyphenols but increased by 3-fold with increasing iron concentration with a concomitant yield decrease of scission product, protocatechuic acid. Two pathways of degradation of anthocyanins were identified: a major metal-catalyzed oxidation followed by condensation and a minor scission which represents about 10% of degraded anthocyanins., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Degradation parameters of two main anthocyanins from roselle extract (Hibiscus sabdariffa L.) stored at different temperatures (4-37°C) over 60days were determined. Anthocyanins and some of their degradation products were monitored and quantified using HPLC-MS and DAD. Degradation of anthocyanins followed first-order kinetics and reaction rate constants (k values), which were obtained by non-linear regression, showed that the degradation rate of delphinidin 3-O-sambubioside was higher than that of cyanidin 3-O-sambubioside with k values of 9.2·10(-7)s(-1) and 8.4·10(-7)s(-1) at 37°C respectively. The temperature dependence of the rate of anthocyanin degradation was modeled by the Arrhenius equation. Degradation of delphinidin 3-O-sambubioside (Ea=90kJmol(-1)) tended to be significantly more sensitive to an increase in temperature than cyanidin 3-O-sambubioside (Ea=80kJmol(-1)). Degradation of these anthocyanins formed scission products (gallic and protocatechuic acids respectively) and was accompanied by an increase in polymeric color index., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Delphinidin-3-O-sambubioside and cyanidin-3-O-sambubioside are the main anthocyanins of Hibiscus sabdariffa calyces, traditionally used to make a bright red beverage by decoction in water. At natural pH, these anthocyanins are mainly in their flavylium form (red) in equilibrium with the quinonoid base (purple) and the hemiketal (colorless). For the first time, their acidity and hydration equilibrium constants were obtained from a pH-jump method followed by UV-vis spectroscopy as a function of temperature from 4 to 37 °C. Equilibrium constant determination was also performed by multivariate curve resolution (MCR). Acidity and hydration constants of cyanidin-3-O-sambubioside at 25 °C were 4.12 × 10(-5) and 7.74 × 10(-4), respectively, and were significantly higher for delphinidin-3-O-sambubioside (4.95 × 10(-5) and 1.21 × 10(-3), respectively). MCR enabled the obtaining of concentration and spectrum of each form but led to overestimated values for the equilibrium constants. However, both methods showed that formations of the quinonoid base and hemiketal were endothermic reactions. Equilibrium constants of anthocyanins in the hibiscus extract showed comparable values as for the isolated anthocyanins.

Background: The stability of anthocyanins and colour of aqueous extracts from roselle (Hibiscus sabdariffa L.) was investigated during storage at 4-45 °C. The effect of the extraction procedure (cold or hot extraction with or without pasteurisation) on the kinetic behaviour was determined., Results: Data analysis showed first-order kinetics for the evolution of anthocyanin content, colour density, colour strength and browning index. Three models (Arrhenius, Eyring and Ball) were used to represent the temperature dependence of the reaction rates. The three models allowed the prediction of colour modifications according to the storage temperature over 6 months. Activation energies ranged from 22 to 26 kJ mol(-1) for anthocyanin degradation and from 18 to 34 kJ mol(-1) for colour parameter modification. The degradation rate during storage depended on the extraction procedure. When heated, the extracts were clearly less stable. Their colour changed faster during storage especially when hot water and pasteurisation were used., Conclusion: Although the anthocyanin content and initial colour were not modified, the extraction conditions, especially temperature, greatly affected the stability of the extracts during storage. Further studies are needed to understand the mechanisms involved., (Copyright © 2011 Society of Chemical Industry.)

Monomeric anthocyanin degradation and nonenzymatic browning (NEB) index have been determined in reconstituted blackberry juice heated at high temperature in a hermetically sealed cell. Statistical analysis demonstrated that, when the temperature range (100-180 degrees C) was divided into two subranges (100-140 and 140-180 degrees C) for anthocyanin degradation, reaction kinetics were well represented by two sequential first-order reactions. The activation energy for NEB from 100 to 180 degrees C (106 kJxmol(-1)) was slightly higher than the anthocyanin value at the lower temperature range (92 kJxmol(-1)), but was more than twice the value for the higher range (44 kJxmol(-1)). The reaction rate constant at 140 degrees C for anthocyanin degradation (3.5 x 10(-3) s(-1)) was two times that for the NEB index (1.6 x 10(-3) s(-1)). Hence, anthocyanin degradation was faster than the appearance of NEB products. The non-isothermal method developed allows estimating kinetic parameters and thereby generating temperature profiles of heat processes that would help preserve the nutritional properties of foods during high-temperature processes.

Anthocyanin stability was assessed over temperatures ranging from 30 to 90 degrees C for seven products: blood orange juice [Citrus sinensis (L.) Osbeck]; two tropical highland blackberry juices (Rubus adenotrichus Schlech.), one with high content and the other with low content of suspended insoluble solids (SIS); and four roselle extracts (Hibiscus sabdariffa L.). The blackberry juice showed the highest content of anthocyanins with 1.2 g/L (two times less in the roselle extracts and 12 times less in the blood orange juice). The rate constant for anthocyanin degradation and isothermal kinetic parameters were calculated according to three models: Arrhenius, Eyring, and Ball. Anthocyanins in blood orange juice presented the highest rate constant for degradation, followed by the blackberry juices and roselle extracts. Values of activation energies were 66 and 37 kJ/mol, respectively, for blood orange and blackberry and 47-61 kJ/mol for roselle extracts. For the blackberry juices, a high SIS content provided only slight protection for the anthocyanins. The increasing content of dissolved oxygen, from 0.5 to 8.5 g/L, did not significantly increase the rate constant. For both isothermal and nonisothermal treatments, all three models accurately predicted anthocyanin losses from different food matrices.

Summary: Slices (1.5 mm thick) of green papaya were impregnated through osmotic dehydration with a blackberry juice–sucrose solution to produce an intermediate moisture product. The effect of processing temperature (T) and sucrose‐added molality (msucrose) on mass transfer during the operation was assessed, using a response surface methodology (RSM). The RSM was used to model water loss, sugar and anthocyanin gain during the process. Increasing sucrose molality resulted in increasing water loss and sugar gain, but decreasing anthocyanin gain. Water transfer therefore limits anthocyanin impregnation, but not sucrose incorporation. Afterwards, the impact of heat treatment at high temperatures was analysed, using numerical simulation. The conditions of the combined process, designed to achieve an anthocyanin‐rich final product, are low sucrose‐added molalities (sucrose molality < 1 mol kg–1) and high processing temperatures (T > 50 ºC) for osmotic dehydration, coupled with high‐temperature, short‐time (HTST) heat treatments for product stabilisation. [ABSTRACT FROM AUTHOR]

Nanofiltration membranes with molecular weight cut-off around 200 Da were evaluated to concentrate anthocyanins and ellagitannins in a blackberry juice. Temperature was 30°C and cross-flow velocity 0.3 m/s. Transmembrane pressures varied from 0.5 to 3 MPa. At volumetric reduction ratio (VRR) of 1, higher transmembrane pressures caused an increase of permeate flux and of retention of total anthocyanins (>94%) and total soluble solids (44-97%). Every membrane presented 100% of total ellagitannin retention. Results were represented using the solution-diffusion model. NF270 membrane at 3 MPa showed the highest potential for concentration of blackberry's main polyphenolic compounds (highest permeate flux and solute retention). Nevertheless, a simulated increase of VRR showed that permeate flux declined as the concentration of the feed solution increased. NF270 membrane may also be of interest to deacidify the juice, since at high pressures, sugars were completely retained and retention of acids was under 90%. Practical Applications The concentration of phytochemicals by means of membrane technologies is of interest to the food industry, because the operations replace evaporation processes that are energy-intensive and use high temperatures that can reduce the compounds' bioactivities. The results presented in this study may be valuable for processors that aim to concentrate fruit juices and extracts enriched with phytochemicals (such as anthocyanins and ellagitannins), by using nanofiltration. Furthermore, results show that nanofiltration membranes at specific operating conditions may not only be employed to concentrate, but also to deacidify fruit juices and extracts. This operation provides advantages when compared to other technologies such as calcium salt precipitation, ion-exchange resins and electrodialysis. [ABSTRACT FROM AUTHOR]

Introduction The effect of temperature on the stability of three purified anthocyanin sources in a soft drink (pH 3, 10 °Brix) stored at (4, 20, 30 and 50) °C for 60 days was investigated. Materials and methods. Anthocyanins from Andean blackberries (Rubus glaucus Benth.), açai (Euterpe oleracea Mart.) and black carrot (Daucus carota L.) were purified and concentrated on a laboratory scale by adsorption to a styrene divinylbenzene copolymer. Two classical empirical approaches (Arrhenius and Ball models) were used to describe the thermal degradation kinetic of these three anthocyanins. Results. No degradation was detected during the refrigerated storage (4 °C). At all temperatures, the degradation rate constant (k) for black carrot anthocyanins was less than those in açai and blackberry (0.42 × 10-2, 0.77 × 10-2 and 1.08 × 10-2).d-1 respectively, at 30 °C). Anthocyanins in black carrot degraded less rapidly than those in açai and Andean blackberry. The activation energy (Ea) for degradation of black carrot anthocyanins was (63.2 ± 4.3) kJ.mol-1, and (66.3 ± 2.7) kJ.mol-1 and (91.2 ± 0.4) kJ.mol-1 for açai and blackberry anthocyanins, respectively, at 20–50 °C. These higher Ea of blackberry anthocyanins as compared with those of black carrot and açai imply that a small temperature increase is sufficient to degrade them more rapidly. Conclusion. Our results clearly showed that anthocyanins from black carrot have a good stability during thermal storage (4 °C to 50 °C) with regard to blackberry and açai anthocyanins. Acylation of black carrot anthocyanins probably explains their greater stability. Acylated anthocyanins have shown to be promising alternatives to the use of synthetic dyes in drink systems [ABSTRACT FROM PUBLISHER]

The açai juice is an Amazonian product that has been exported to various countries around the world. Its main characteristic is the presence of antioxidant compounds especially anthocyanins. Nanofiltration is a membrane separation process that has the ability to separate compounds of low molar weight. Açai juice clarified by microfiltration was used as feed to evaluate nanofiltration membranes of different manufacturers regarding the permeate flux and the retention of anthocyanins. All the evaluated membranes were efficient in retaining the anthocyanins from the açai juice. NF 270 membrane, a composite membrane composed by a polyamide top layer and a polysulphone microporous support, presented the highest water permeability before and after the nanofiltration of açai juice. In addition, this membrane also presented the highest value of permeate flux in the nanofiltration process of açai juice as well as the anthocyanins retention above 99%. The effect of fouling for this membrane was approximately 28%. The observed results showed the potential of nanofiltration on the recovery of anthocyanins from açai fruit. [ABSTRACT FROM AUTHOR]

Abstract: The effect of water activity on anthocyanin degradation and non-enzymatic browning (NEB) indices was determined in a blackberry juice system heated to high temperature. Blackberry juice samples mixed with quartz sand at three different water activities (a w of 0.34, 0.76 and 0.95) and having the same concentration of anthocyanins (51±4mg100g−1 WB) were heated in a hermetically sealed reactor under non-isothermal conditions (100 to 140°C). Reaction kinetics were well-represented by first-order reaction models. A non-isothermal method was used for the identification of kinetic parameters, and the confidence interval for each parameter was determined via Monte-Carlo simulations. The estimated parameters revealed an increase in the anthocyanin degradation reaction rate constant (k ref ) from 0.9 to 3.5×10−3 s−1 as the water activity decreased from 0.99 to 0.34. The corresponding activation energies (E a ) for anthocyanins and NEB index were modified to a lesser extent by variations in water activity. Hence, the reduction of water activity had a negative effect on anthocyanin stability at high temperatures. [Copyright &y& Elsevier]

The stability of ascorbic acid and colour intensity in pasteurised blood orange juice ( Citrus sinensis [L.] Osbeck) during one month of storage was investigated at 4–37 °C. The effects of ascorbic acid fortification (at 100, 200 mg L −1 ) and deaeration, temperature/time storage on the kinetic behaviour were determined. Ascorbic acid was monitored by HPLC–DAD and colour intensity by spectrophotometric measurements. Degradation kinetics were best fitted by first-order reaction models for both ascorbic acid and colour intensity. Three models (Arrhenius, Eyring and Ball) were used to assess the temperature-dependent degradation. Following the Arrhenius model, activation energies were ranged from 51 to 135 kJ mol −1 for ascorbic acid and from 49 to 99 kJ mol −1 for colour intensity. The effect of storage temperature and deaeration are the most influent factors on kinetics degradation, while the fortification revealed no significant effect on ascorbic acid content and colour intensity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Separation of ellagitannins by ultrafiltration (UF) was tested in blackberry juice. [•] Six organic plate and frame membranes (1–150kDa) were used from 0.5 to 3MPa. [•] Retention was 100% for ellagitannins and depended on pressure for anthocyanins. [•] Modeling confirmed interest in UF to purify ellagitannins through diafiltration. [Copyright &y& Elsevier]

Abstract: Solid–liquid extraction of anthocyanins from calyces of Hibiscus sabdariffa L. was studied to evaluate the influence of the operating parameters. Solid-to-solvent ratio and particle size had the main impact on anthocyanin extraction efficiency. Maximum yield of anthocyanins (88%) was obtained at 25°C with the highest solid-to-solvent ratio (1/25). The decrease in the particle size of the calyces from 2cm to 150μm drastically reduced the extraction time. The increase of temperature reduced the extraction time by increasing the diffusion coefficient (3.9×10−11–1.35×10−10 m2 s−1 between 25 and 90°C) but did not modify the extraction yield. A simple extraction model that integrated anthocyanin thermo-degradation kinetic was proposed. A good agreement between the predicted results of the models and experimental data was demonstrated. From a solid-to-solvent ratio of 1/5, an extraction yield of 63% and an anthocyanin concentration of 0.3gL−1 could be obtained in less than 10min. [Copyright &y& Elsevier]

Abstract: Ten nanofiltration flat-sheet membranes and eight tight ultrafiltration membranes with nominal MWCOs ranging from 0.2 to 150kDa were tested to concentrate anthocyanin extract from roselle. A pilot system was used, which featured a membrane cell with an effective area of 0.0155m2. Permeate fluxes were recorded for transmembrane pressures between 0.5 and 3.0MPa, while keeping all other operating conditions constant (volumetric reduction ratio 1, 35°C). Retention values of total soluble solids, acidity and anthocyanins increased with transmembrane pressure. With similar permeate fluxes at average transmembrane pressure, retention of anthocyanins is significantly higher for nanofiltration membranes than for ultrafiltration membranes. A membrane was then selected for an industrial trial on the basis of its flux, retention of compounds of interest and energy consumption per liter of permeate. The trial using a 2.5-m2 filtration surface, could concentrate roselle extract from 4 to 25g total soluble solids per 100g, with 100% retention of anthocyanins. No significant damages were observed when comparing concentrate quality with the initial roselle extract. [Copyright &y& Elsevier]