Increased Color Stability Research Articles

Evaluation of the colour stability of different ceramic materials with two thicknesses

Society places a great emphasis on aesthetics, & there is a constant rise in the demands placed on dental restorations' aesthetics. The aim of this in-vitro research was to study the impact of the finishing protocol on the color stability parameter of different glass-ceramic materials with two different thicknesses, before & after thermocyling. One hundred twelve specimens had been prepared with standard dimensions of one mm & two mm thickness & ten mm diameter for the four different glass-ceramic materials. The ceramic specimens had been separated into 4groups according to ceramic material (n=28): IPS e.max Press, CeraMotion, Rosetta SP & CeltraPress, each group had been subdivided into two sub-groups according to the specimen thickness (n=14): 1 mm and 2 mm. Each sub-group was further split into 2 divisions according to the finishing protocol (n=7): glazed only & polished then glazed. The results of our study all samples have shown color change within visually perceptible but clinically acceptable level (more than 1 and less than 3.7), emax glazed samples (1mm&2mm) together with emax glazed and polished samples (1mm) have shown significantly higher ΔE beyond the clinically acceptable level. Increasing ceramic thickness from 1 mm to 2 mm has shown better color stability in Emax group. Polishing before glazing increased color stability in Emax while decreased it in Celtra.

Strawberry Post-Harvest Anthocyanin Development to Improve the Colour Stability of Strawberry Nectars

Strawberry nectars have increased colour stability when produced from overripe, darker, and redder strawberries, with a high anthocyanin concentration. The post-harvest storage of strawberries has been shown to develop these properties. Nectars are frequently produced from strawberries rejected for fresh sale due to poor colour, which are insufficiently ripe to produce colour-stable nectars. This study investigated post-harvest anthocyanin development in strawberries to improve the colour and colour stability of nectars, which is the first time these developments were studied for beverage production. Strawberries at five ripeness stages were stored at 20 °C for 1 and 2 days prior to nectar production. The anthocyanin content of nectars was determined by a pH-differential method, and the colour stability was tracked for 12 weeks using a consumer Acceptance Factor, derived from CIELAB colour components. The anthocyanin content and colour stability were highly correlated, and both were dependent on ripening, with larger increases observed in under-ripe strawberries, and small to no improvement in overripe samples. Stored partially coloured strawberries produced nectars with equivalent colour stability to non-stored strawberries of normal ripeness. This allowed strawberries that were previously unsuitable for both fresh sale and nectar production to be used as a feedstock for nectar production, reducing food waste.

Impact of Synthetic Food Colouring Agents on Aquatic Ecosystems and Human Health

Colour is an important factor to enhance the consumer acceptance and appetizing value towards food and beverages. Foods are coloured with both natural and artificial/ synthetic food dyes. Instead of natural food colours, synthetic food colours are now widely employed by the food industry because of its superior features (cheap cost, enhanced look, greater colour intensity, increased colour stability, and consistency). Life of synthetic colorants is quite long as they are highly soluble in water and oil. Based on their solubility, synthetic colorants are classified into fat soluble synthetic colours, lake colours, water soluble synthetic colours. Colouring agents have spread across the water and soil ecosystem, this is because they are mass-produced and wider application. Samples of water, suspended particles, sediment, and wild fish have all tested positive for food dyes. As a result, they are regarded as micropollutants in aquatic systems. Cancers, mutations, neurotoxic effects, decreased haemoglobin concentrations, allergic reactions, food hypersensitivity, abdominal pain, worsened asthmatic symptoms, vomiting, and diarrhoea are just some of the potential dangers to one's health, which can result from using synthetic colours that aren't allowed or using them in excess. This review critically evaluates the effect of synthetic food colouring agents on aquatic environment and human health. We found that there is a definite unfavourable effect of synthetic organic additives on aquatic life and human health. Some synthetic colouring dyes have toxicological qualities and pharmacological action, thus it's important to keep an eye on water bodies. Synthetic organic food colour in water ecosystems may constitute a harmful effect on animals or human health’s, it is urgent need to evaluate the hazard potential of these substances. For this reason, it is strongly suggested that both consumers and manufacturers of food colours should be aware about the rules and regulations regarding food colours.
 GRAPHIC ABSTRACT

Polyphenol Extracts from Sage (Salvia lavandulifolia Vahl) By-Products as Natural Antioxidants for Pasteurised Chilled Yoghurt Sauce.

Sage by-product extracts (SE) are a valuable source of phenolic acids and flavonoids for food applications. The objective was to test two SE as antioxidants in pasteurised chilled yoghurt sauces against oxidation. Two SE of different polyphenol total content and profile were selected: SE38 (37.6 mg/g) and SE70 (69.8 mg/g), with salvianic and rosmarinic acid as the main polyphenols, respectively. Four experimental low-fat yoghurt sauces were formulated: untreated; SE70/2 (0.16 g/kg); SE38 (0.3 g/kg); and SE70 (0.3 g/kg). The stability of phenolic acids, microbiological quality (mesophilic bacteria, moulds and yeasts, and L. monocytogenes), and oxidative stability (lipids, colour, and pH) were studied in the sauces after pasteurisation at 70 °C for 30 min (day 0) and stored by refrigeration (day 42). Pasteurisation and further chilling ensured the microbiological quality and inhibition of microbial growth could not be evidenced, although SE70 showed some antimicrobial potential. Both SE showed good properties as antioxidants for yoghurt sauces. This finding was based on two results: (i) their main polyphenols, salvianic and rosmarinic acids, resisted to mild pasteurisation and remained quite stable during shelf life; and (ii) SE improved radical scavenging capacity, delayed primary and secondary lipid oxidation, and increased colour stability, contributing to sauce stabilisation. SE38 had a better antioxidant profile than SE70; therefore, the selection criteria for SE should be based on both quantity and type of polyphenols. Due to their stability and antioxidant properties, sage polyphenols can be used as natural antioxidants for clean-label yoghurt sauces.

The Genetic Basis of Anthocyanin Acylation in North American Grapes (Vitis spp.).

Hydroxycinnamylated anthocyanins (or simply ‘acylated anthocyanins’) increase color stability in grape products, such as wine. Several genes that are relevant for anthocyanin acylation in grapes have been previously described; however, control of the degree of acylation in grapes is complicated by the lack of genetic markers quantitatively associated with this trait. To characterize the genetic basis of anthocyanin acylation in grapevine, we analyzed the acylation ratio in two closely related biparental families, Vitis rupestris B38 × ‘Horizon’ and ‘Horizon’ × Illinois 547-1, for 2 and 3 years, respectively. The acylation ratio followed a bimodal and skewed distribution in both families, with repeatability estimates larger than 0.84. Quantitative trait locus (QTL) mapping with amplicon-based markers (rhAmpSeq) identified a strong QTL from ‘Horizon’ on chromosome 3, near 15.85 Mb in both families and across years, explaining up to 85.2% of the phenotypic variance. Multiple candidate genes were identified in the 14.85–17.95 Mb interval, in particular, three copies of a gene encoding an acetyl-CoA-benzylalcohol acetyltransferase-like protein within the two most strongly associated markers. Additional population-specific QTLs were found in chromosomes 9, 10, 15, and 16; however, no candidate genes were described. The rhAmpSeq markers reported here, which were previously shown to be highly transferable among the Vitis genus, could be immediately implemented in current grapevine breeding efforts to control the degree of anthocyanin acylation and improve the quality of grapes and their products.

In-situ electro-polymerization of fluorescent electrochromic thin films based on charge-transfer complexes

Fluorescent electrochromic (FEC) materials, which reversibly change their both fluorescence and absorption via electrochemical reactions in response to applied potentials, have received extensive attention. Herein we directly obtained poly (2Z,2′Z)-3,3′-(1,4-phenylene)bis(2-(4-((6-(9H-carbazol-9-yl)hexyl)oxy)phenyl)acrylonitrile) P(CHDCS) and poly (2Z,2′Z)-3,3′-(2,5-dimethoxy-1,4-phenylene)bis(2-(4-((6-(9H-carbazol-9-yl)hexyl)oxy)phenyl)acrylonitrile) P(CHDCSM) as thin films on electrodes via electro-polymerization (EP) from linear donor-acceptor (D-A) monomers with isolated π-conjugation. Surprisingly, interchain charge-transfer complexes (CTCs) with mixed D-A stacks were generated between electroactive bis-carbazole (D) and luminescent dicyanodistyrylbenzene (A) units during the EP process. Consequently, significantly redshifted and bright orange fluorescence (∼600 nm) originated from intermolecular CT excitons were observed from both polymers, which could be reversibly switched upon applied potentials. This is the first time that the CTCs have been prepared via EP and applied as FEC materials. Moreover, the stronger intermolecular CT effect gives rise to an enhancement of electrical conductivity and FEC response in P(CHDCS), resulting in high optical contrasts (T = 33.6%, Ion/Ioff = 28.3) and fast FEC switching (coloring 1.25 s, fading 0.53 s, quenching 2.40 s, brightening 6.17 s) as well as good reversibility. In addition, the CTCs improve the spin delocalization of bis-carbazole radical cations, leading to increased color stability of the FEC films by a decay of only 1.2% in 2 h with no power supply after coloration. This work not only affords an innovative CTC design strategy for FEC materials but also paves the way for constructing highly-performed and energy-efficient FECs via one-step electrochemical methods.

Peracetate/singlet oxygen chemistry used in post-bleaching of kraft pulp as a practical oxidant for paper machines

The use of a novel sodium peracetate/singlet oxygen chemistry for brightening bleached kraft pulp shows exciting potential for technical performance, supply logistics, safety, and cost reduction. Potential chemical carryover to the paper machine raises questions about whether peracetate will impact paper machine performance, such as metal corrosion, useful press felt life, and interference with existing biocide programs or paper machine chemistry. Sodium peracetate/singlet oxygen chemistry can be used in high-density storage chests for brightening/whitening and to increase color stability. Any oxidant used directly before the paper machine has the possibility of impacting paper machine operations. Traditional oxidants used in bleaching, such as chlorine dioxide and hydrogen peroxide, are known to cause corrosion on machinery metals and press felts. Hydrogen peroxide residuals can interfere with common biocide programs. Traditional oxidants used in biocide treatments themselves significantly degrade press felt life when the rule-of-thumb concentration thresholds are exceeded. Sodium peracetate is evaluated in this paper for its impact on nylon press felt fiber degradation, metal corrosion, and interference with typical biocide programs. Laboratory results indicate that sodium peracetate/singlet oxygen chemistry is less corrosive than chlorine, bro-mine, and hydrogen peroxide on press felt nylon fiber and can therefore be used at higher levels than those chemistries to increase brightness without increasing negative downstream impact. Sodium peracetate can also be used with current biocide programs without negative impacts such as consumptive degradation. Higher residuals of per-acetate going to the paper machine may be useful as a biocide itself and can complement existing programs, allowing those programs to stay within their safe operating levels and thereby extend press felt useful life.

Anthocyanins extraction from Hibiscus sabdariffa and identification of phenolic compounds associated with their stability.

One of the main disadvantages of red pigments used in foods is their low extraction yield and storage stability. Roselle flowers are sources of anthocyanins; however, these are unstable during storage, but this could be improved with phenolic compounds, which establish bonds with the anthocyanins. The aim of this work was to identify conditions to improve the extraction efficiency and color stability of Hibiscus sabdariffa extract and, furthermore, to identify the phenolic compounds associated with color stability of roselle. The temperature of extraction (35 and 75 °C), the time of extraction (15 and 60 min), type of acid (acetic and citric), percentage of acid (0.5 and 2.0%) and the water:ethanol ratio (20:80 and 80:20) did not affect the yield of anthocyanins; only the solid:solvent ratio had an effect in the anthocyanin extraction yield. The extraction with 80% ethanol decreased up to 50% the anthocyanin degradation in the extracts stored at 4, 25, 35, 45, and 80 °C. Phenolic acids and flavonoids were quantified by ultrahigh-performance liquid chromatography coupled with triple quadrupole electrospray ionization mass spectrometry. These compounds were analyzed using principal component analysis, and the H. sabdariffa extract, with greater stability, was found to be associated with the presence of quercetin, myricetin, kaempferol 3-O-glucose, ellagic acid, and rutin. H. sabdariffa extract with increased color stability was extracted with a higher proportion of ethanol and the improvement in the color stability was attributed to the co-extraction of phenolic compounds, principally flavonoids that could interact with anthocyanins and stabilize them. © 2020 Society of Chemical Industry.

Assessment of the Stability of Fresh Beef Patties with the Addition of Clove Extract during Frozen Storage.

The study assessed the stability for fresh beef patties with the inclusion of clove extract (CE) as a natural antioxidant in comparison to butylated hydroxytoluene (BHT) and ascorbic acid (AA) at frozen storage. Four different patties were made dependent on the added antioxidants: control (added no antioxidants), added with 0.02% BHT, 0.05% AA, and 0.1% CE. Inclusion of BHT, AA, and CE resulted in a significant reduction of thiobarbituric acid reactive substances (TBARS) and hue angle (h°) value and increase of redness (CIE a*) and chroma (C*) values (p<0.05). BHT, AA, and CE were observed effectively to retard lipid oxidation and increase color stability. BHT and AA revealed significantly (p<0.05) higher thiol content than the control and CE. However, the reduction percentage for thiol content in CE treated patties was lower than the control and AA-treated patties from first to last time of storage. Moreover, inclusion of AA and CE led to significantly (p<0.05) increased heme iron content when compared to BHT and the control. In conclusion, CE can replace the application of AA and BHT while improving lipid stability, heme iron content, and color stableness of fresh beef patties throughout frozen storage.

Influence of different thermopolymerization methods on composite resin microhardness.

BackgroundAdditional heat polymerization in composite resins allows greater effective­ness of microhardness, flexural strength, fracture tough­ness, wear resistance, and increased color stability. Material and Methods150 composite resin specimens were made using a 4 mm diameter and 2 mm thick bipartite steel matrix. Five resins composed of different compositions were tested (Brilliant Everglow/Coltene, Filtek One BulkFill/3M, Filtek P60/3M, Filtek Z350XT/3M, Filtek Z250XT/3M), and for each of them three types of polymerization were tested: light curing only (n=50); photopolymerization + autoclave thermopolymerization (n=50) and photopolymerization + microwave thermopolymerization (n=50). Each specimen was submitted to three indentations by means of the Vickers microhardness test, applying a load of 300gf, associated with the time of 15s. Data were analyzed descriptively by means of statistics, standard deviation and coefficient of variation and inferentially by the F test (ANOVA) in the comparison between groups. The margin of error used in statistical test decisions was 5%. ResultsThe highest vicker microhardness averages were from the Control group (light curing only) on P60 (82.16) and Z250 XT (79.61) resins. The lowest averages were all verified on Brilliant Everglow resin in all polymerization methods studied: Photopolymerization (37.32), with microwave (43.80) and autoclave (45.12), followed by Bulk Fill 3M resin, ranged from 52.23 to 59.15. ConclusionsBoth autoclave and microwave thermopolymerization methods showed similar behavior on the microhardness of the composites studied. Considering the resin type, there was a varied behavior compared to thermopolymerization, which increased the microhardness values for Brilliant Everglow resins (Coltene) and Filtek One Bulkfill (3M) and decreased for Filtek P60, Filtek Z350XT and Filtek Z250XT resins. Key words:Dentistry, composite resins, polymerization.

Study of the multi-equilibria of red wine colorants pyranoanthocyanins and evaluation of their potential in dye-sensitized solar cells

Herein, a series of 3-O-glucosilated pyranoanthocyanin derivatives were synthesized following a bio-mimetic approach. The compounds were studied by means of UV–Vis spectroscopy in order to establish their chemical equilibria and determine the stability of the colored species over the pH range. The resistance of pyranoanthocyanins to hydration grants this family of compounds, closely related to anthocyanins, increased color stability. Finally, the synthetized compounds were successfully applied as light harvesters in DSSCs and relations between dye structure and cell efficiency were found. The influence of different linker units (carboxylate, catechol) and electron-donor groups (methoxy, hydroxyl, methyl), as well as the presence of sugar moieties have impact in the various parameters related to DSSC efficiency. An overall efficiency of 1.57% was obtained for the best performing compound, methylpyranocyanidin-3-O-glucoside. The impact of using different additives was also studied and the results compared with other families.

Muscle-Specific Mitochondrial Functionality and Its Influence on Fresh Beef Color Stability.

During retail display tenderloin steaks packaged in PVC overwrap discolor quicker than strip loin steaks. This research determines the basis for muscle-specific differences in color stability. The results indicate that mitochondria present in tenderloin lose its functionality faster than strip loin mitochondria. Developing strategies to minimize muscle-specific differences in mitochondrial changes can increase color stability and value of fresh beef.

Crystallization-assisted nano-lens array fabrication for highly efficient and color stable organic light emitting diodes.

To date, all deposition equipment has been developed to produce planar films. Thus lens arrays with a lens diameter of <1 mm have been manufactured by combining deposition with other technologies, such as masks, surface treatment, molding etc. Furthermore, a nano-lens array (NLA) with a sufficiently small lens diameter (<1 μm) is necessary to avoid image quality degradation in high resolution displays. In this study, an organic NLA made using a conventional deposition technique - without combining with other techniques - is reported. Very interestingly, grazing-incidence small-angle X-ray scattering (GI-SAXS) experiments indicate that the NLA is formed by the crystallization of organic molecules and the resulting increase in surface tension. The lens diameter can be tuned for use with any kind of light by controlling the process parameters. As an example of their potential applications, we use NLAs as a light extraction film for organic light emitting diodes (OLEDs). The NLA is integrated by directly depositing it on the top electrode of a collection of OLEDs. This is a dry process, meaning that it is fully compatible with the current OLED production process. Devices with NLAs exhibited a light extraction efficiency 1.5 times higher than devices without, which corresponds well with simulation results. The simulations show that this high efficiency is due to the reduction of the guided modes by scattering at the NLA. The NLAs also reduce image blurring, indicating that they increase color stability.

Effect of newly developed pigments and ultraviolet absorbers on the color change of pigmented silicone elastomer.

Aim and Objective:The aim and objective of the study is to evaluate effect of ultraviolet (UV) stabilizer (UV absorber Chimassorb 81) on color change of pigmented silicone elastomer when commercially available (red and yellow), and newly developed pigments (sicotrans red and sicopal brown) were used.Materials and Methods:Two commercially available pigments – red (P112 Brilliant Red) and yellow (P106 Yellow) and two newly developed pigments – sicotrans red and sicopal brown were studied. In total eight groups made up of nine samples each were fabricated using elastomer with the combinations of the above pigments and UV stabilizer (Chimassorb 81). Groups 1, 3, 5, and 7 contain elastomer in combination with sicotrans red, sicopal brown, yellow and red pigments, respectively. Similarly, groups 2, 4, 6, and 8 along with elastomer and pigments (sicotrans sed, sicopal brown, yellow and red, respectively) contain the UV stabilizer (Chimassorb 81). Samples were subjected to aging in an accelerated weathering chamber (Weather-Ometer). Color values CIE (Commission Internationale d’Eclairage) L*, a*, and b * were measured at baseline and after 1000 h of weathering. Change in color (Delta E) was calculated.Results:All groups showed a significant color change at 1000 h. Groups 1, 2, 3, and 4 showed a statistically significant less change in both colors (sico trans red and sicopal brown) compared to groups 5,6,7, and 8 (commercial pigments-Red and Yellow). Overall, the change in the color in groups with the UV stabilizer (Chimassorb) was less when compared to the groups where the stabilizer was not used.Conclusion:The newly developed pigment led to increased color stability as compared to commercially available pigments. Addition of UV stabilizer, Chimassorb led to a further reduction in color change of the pigmented elastomer.

Delayed Light Activation Improves Color Stability of Dual‐Cured Resin Cements

To evaluate the color change caused by post-irradiation conversion (ΔE24h and ΔE8days ) and artificial aging (ΔEAGING ) of resin cements light activated through ceramics of different opacities immediately and 6minutes after manipulating the material. Resin cement disks (Allcem and LuxaCore) were light activated through ceramics (without ceramic, e.max HT, LT, and MO) immediately and 6minutes after the manipulation (n = 10). Spectrophotometry was used to evaluate ΔE24h and ΔE8 days after 37˚C-dry-dark-storage for 24 hours and 8 days, and ΔEAGING after 60˚C-water-storage for 24 hours. Data were analyzed with three-way ANOVA and Tukey's HSD (α = 0.05). Regarding the post-irradiation color change, significant differences were found between the cements (p < 0.0001), light activation protocols (p = 0.037), and ceramics (p < 0.001). The immediate activation (16.2 ± 0.1) showed lower ΔE values than the delayed activation (16.5 ± 0.1). Ceramics influenced the ΔE values as follows: MO (14.0 ± 1.2) < LT (14.9 ± 1.2) ≈ HT (15.4 ± 1.2) < control (21.2 ± 1.2). Regarding ΔEAGING , significant differences were found between cements (p<0.001), light activation (p = 0.006), and ceramics (p < 0.001). The delayed activation (8.4 ± 0.1) showed lower values than the immediate activation (8.9 ± 0.1). Ceramic spacers influenced ΔEAGING as follows: control (5.6 ± 0.2) < MO (6.6 ± 0.2) < HT (11.0 ± 0.2) ≈ LT (11.5 ± 0.2). The delayed light activation resulted in increased color stability, while the ceramic interposition resulted in lower color stability.

Colour-related phenolics, volatile composition, and sensory profile of Nero di Troia wines treated with oak chips or by micro-oxygenation

The changes of Nero di Troia wines submitted to micro-oxygenation or treatment with oak chips were studied. Oak chips favoured polymerization reactions (SPP, LPP, I HCl, polymeric phenols, and polymeric pigments, respectively +28, +67, +44, +60, and +73 % in comparison with the untreated wines, 12 months after racking). The polymerization reactions increased colour stability (colour intensity, and % of red and blue colour of the oak-treated wines were +11, +2, and +10 % compared to the control). At the end of ageing, the oak-treated wines had the highest concentrations of alcohols, carbonyl compounds, and lactones, while the highest contents of acids and esters were detected in the micro-oxygenated wines. The sensory profile of the oak-treated wines was characterized by the attenuation of floral, fruity, and vinous attributes. Concerning the phenolic profile, micro-oxygenated wines showed the highest concentrations of anthocyanins (+23 % respect to the untreated samples and +306 % respect to the oak-treated ones) and of flavan-3-ols (+24 % respect to the untreated samples and +95 % respect to the oak-treated ones). Micro-oxygenation reduced astringency and herbaceous character and intensified spicy and fruity flavours.

Effects of modeling liquid/resin and polishing on the color change of resin composite.

Modeling liquids/resins have been used to build up resin composite (RC) restorations, although there is a lack of information regarding their effects on the color stability of the latter. Therefore, the purpose of the present study was to evaluate the effects of the presence of modeling liquid between layers of RC and the finishing/polishing state of the material on color change in specimens exposed to red wine staining over time. Specimens were prepared by placing four increments (±0.5 mm thick) of RC (Filtek™ Z350 XT, 3M ESPE) into molds; half of which were prepared by applying modeling liquid (Scotchbond™ Multi-Purpose™ Adhesive, SBMP, 3M ESPE) between the layers of RC, whereas the other half were prepared without SBMP (control). Light-activation was performed after application of the final RC layer using a light-emitting diode (Radii, SDI) curing unit with an irradiance of 900 mW/cm2 for 20 s. Each group was divided according to the surface finishing protocol (n = 7): nothing (non-polished) or polishing with Sof-Lex™/diamond paste (polished). Initial colors of the specimens were evaluated with a digital spectrophotometer and the CIEL*a*b* color system. The specimens were stored in wine (37°C) for 12 months, and the color measurements were reassessed after 4, 6, and 12 months of storage. Scanning electron microscopy (SEM) analysis was performed at the end. Data were analyzed using ANOVA and Tukey's test (α = 5%). The presence of SBMP resulted in lower overall color change of the RC as compared with the control. The non-polished specimens exhibited a significantly higher color change than the polished specimens. SEM images corroborated the previous findings. In summary, the use of modeling liquid between layers of RC shows potential for application to reduce or delay the staining process of RC over time. Moreover, polishing is essential to provide increased color stability of the RC restoration.

Shelf life, physicochemical, microbiological and antioxidant properties of purple cactus pear (Opuntia ficus indica) juice after thermoultrasound treatment

The objective of this study was to evaluate changes in color, betalain content, browning index, viscosity, physical stability, microbiological growth, antioxidant content and antioxidant activity of purple cactus pear juice during storage after thermoultrasonication at 80% amplitude level for 15 and 25min in comparison with pasteurized juice. Thermoultrasound treatment for 25min increased color stability and viscosity compared to treatment for 15min (6.83 and 6.72MPa, respectively), but this last parameter was significantly lower (p<0.05) compared to the control and pasteurized juices (22.47 and 26.32MPa, respectively). Experimental treatment reduced significantly (p<0.05) sediment solids in juices. Total plate counts decreased from the first day of storage exhibiting values of 1.38 and 1.43logCFU/mL, for 15 and 25min treatment, respectively. Compared to the control, both treatments reduced enterobacteria counts (1.54logCFU/mL), and compared to pasteurized juice decreased pectinmethylesterase activity (3.76 and 3.82UPE/mL), maintained high values of ascorbic acid (252.05 and 257.18mg AA/L) and antioxidant activity (by ABTS: 124.8 and 115.6mg VCEAC/100mL; and DPPH: 3114.2 and 2757.1μmol TE/L). During storage thermoultrasonicated juices had a minimum increase in pectinmethylesterase activity (from day 14), and exhibited similar total plate counts to pasteurized juice. An increase of phenolic content was observed after 14days of storage, particularly for treatment at 80%, 25min, and an increase in antioxidant activity (ABTS, DPPH) by the end of storage.

Exogenous acetaldehyde as a tool for modulating wine color and astringency during fermentation

Wine tannins undergo modifications during fermentation and storage that can decrease their perceived astringency and increase color stability. Acetaldehyde acts as a bridging compound to form modified tannins and polymeric pigments that are less likely to form tannin–protein complexes than unmodified tannins. Red wines are often treated with oxygen in order to yield acetaldehyde, however this approach can lead to unintended consequences due to the generation of reactive oxygen species. The present study employs exogenous acetaldehyde at relatively low and high treatment concentrations during fermentation to encourage tannin modification without promoting potentially deleterious oxidation reactions. The high acetaldehyde treatment significantly increased polymeric pigments in the wine without increasing concentrations of free and sulfite-bound acetaldehyde. Protein–tannin precipitation was also significantly decreased with the addition of exogenous acetaldehyde. These results indicate a possible treatment of wines early in their production to increase color stability and lower astringency of finished wines.

Color stability and polymerization behavior of direct esthetic restorations.

The current study evaluated the effect of accelerated artificial aging (AAA) on the color stability (CS) and degree of conversion (DC) of nanofilled and nanohybrid resin composites associated to different adhesive systems in direct esthetic restorations. Eighty bovine incisors were used to obtained dentin blocks (4 × 4 × 1 mm). The restorative systems were bonded to the blocks and photoactivated according to the manufacturer's instructions. Three adhesive systems were used: Adper Scotchbond Multi-Purpose (conventional of three steps), Tetric N-Bond (conventional of two steps) and ClearFill SE Bond (self-etching). Also, two composites were used: Filtek Z350 XT (nanofilled) and IPS Empress Direct (nanohybrid). The restorations were made using a silicone mold placed on top of the prepared dentin blocks (N = 10). CS was measured after 300 hours of AAA by means of ultraviolet light using a spectrophotometer and CIE L*a*b* parameters on the top surface of the composite and at the bonded interface. The DC was performed using Fourier transform infrared spectroscopy (N = 10). Data were analyzed using two-way analysis of variance and Tukey's test (α = 0.05). The adhesive systems had no significant influence on the color stability (ΔE) of either the restoration surface (α = 0.90) or the bonded interface (α = 0.78). However, composite influenced the color as measured by ΔE and isolated coordinates (α < 0.001). The nanohybrid composite showed increased DC values (67%) compared with the nanofilled (61%) with statistically significant differences (α < 0.001). The adhesive system did not affect the final color of direct esthetic restorations. The nanohybrid composite demonstrated a higher DC and increased color stability after AAA compared to the nanofilled composite. The long-term color stability of composite restorations is a critical aspect of esthetic restorative procedures. Optimal Polymerization behavior of resin composite as indicated by the degree of conversion also influence on the color stability after artificial aging of composite restorations.