Wine Color Research Articles

Analysis of phenolics in New Zealand Pinot noir wines using UV-visible spectroscopy and chemometrics

Phenolics are an important group of wine compounds which have been linked with key sensory attributes, including the color and astringency of wines. For winemakers, accurate determination of phenolics is an increasingly important component of the quality monitoring process. One promising approach for the quantification of phenolics is through the use of ultraviolet-visible (UV-Vis) spectroscopy, which is inexpensive and requires minimal sample preparation. Previous research has explored some parts of the UV–vis spectrum for various types of red wines, though none have extensively explored Pinot noir wines, which have a lower average phenolic content than other common varieties such as Cabernet Sauvignon and Merlot. UV-Vis spectra were obtained alongside reference determinations of phenolic compounds using high-performance liquid chromatography, for a set of 155 Pinot noir wines from New Zealand. Partial least squares (PLS) regression models, using the UV-Vis spectra and the reference HPLC measurements, were constructed. Overall, the PLS regression models indicated that phenolic compounds with high concentrations and groups of compounds could be determined with a high degree of accuracy, while for phenolic compounds with lower concentrations the prediction performance was generally less accurate.

Effects of magnetization with neodymium magnets treatment on blueberry wine ageing

The feasibility of magnetization treatment, using neodymium magnets, for blueberry wine ageing was investigated. Two magnetization ageing devices with different operating modes (M1, circulation between two tanks; M2, single-tank circulation) were used to treat new blueberry wine. Changes in the basic characteristics, phenolic substances, antioxidant capacity, and sensory properties were evaluated. The magnetization treatment induced a faster change in the basic characteristics of the wine compared to that of the control. The magnetized blueberry wine showed higher total phenol content, antioxidant capacity, and more volatile compounds. Sensory evaluation showed that the quality of blueberry wine was improved during magnetization ageing. Moreover, the positive influence of the M1 mode on the aforementioned properties was greater than that of the M2 mode. However, when the treatment time was more than 8 weeks, the antioxidant capacity, color, and sensory evaluation of the magnetized blueberry wine were worse than those of the control. These results proved that magnetization treatment could significantly accelerate the early ageing process of blueberry wine. The effect of M1 on the ageing process was better than M2.

Specification and Simplification of Analytical Methods to Determine Wine Color

The color of wine is an important quality parameter essential for the first impression of consumers. The International Organization of Vine and Wine (OIV) recommends two methods to describe wine color: color calculation according to Glories and the determination of coordinates in the CIE L*a*b* color space. The measurement of wine color is often not feasible for winemakers because the required instrumentation is expensive and bulky. In this study, the influence of photometer settings on the calculated color was investigated based on 14 wines. Furthermore, the CIE L*a*b* and Glories system were compared using 56 red and 56 white wines. Photometer settings were found to influence the reproducibility of color determination. In addition, CIE L*a*b* system do not correlate in all wines with the Glories system and Glories probably provides less information about wine color. Using interpolation, CIE L*a*b* coordinates were calculated from single wavelength measurements taken by a small-sized and inexpensive portable analysis system, which could be used by winemakers in the future.

Chemical and Sensory Effects of Cofermentation and Blending of Malbec and Merlot Wines from the Central Coast of California

Background and Aims. Cofermentation and blending are traditional winemaking practices. This study reports their comparative chemical and sensory outcomes. Methods and Results. Malbec and Merlot were made into monovarietal wines, cofermented (COF), blended postalcoholic (PAF), and postmalolactic fermentation (PMLF), at a 50/50 proportion. Wines were followed up to 3 years of bottle aging. Tannins were 50% higher in monovarietal Merlot wines, which improved production of large polymeric pigments in Merlot-based cofermented and blended wines. Addition of Malbec favored production of small polymeric pigments. After 3 years of bottle aging, polymeric pigments were higher in cofermented and blended wines. PMLF blended wines showed 15% improved copigmentation and 25% increase in wine colour. The perception of wine length was positively correlated with red fruit aroma (R2 = 0.94 andp=0.006) and negatively correlated with earthy aroma (R2 = 0.91 andp=0.012). Conclusions. Blending postalcoholic fermentation highlighted more of the individual character of each monovarietal wine in the final blend. Cofermentation and postmalolactic fermentation blending tended to equalize the sensory profile of the resulting wines but also showed higher complexity of aromas than monovarietal wines. Significance of the Study. Cofermentation and blending are both suitable winemaking practices for increasing the polymeric pigment content and the sensory complexity of the resulting wines.

Bioprotection on Chardonnay Grape: Limits and Impacts of Settling Parameters

Background and Aims. If bioprotection has already been proven to limit the development of spoilage flora on musts, its effectiveness against oxidation depends on the winemaking process. To optimize its application, this study analyzed the evolution of the chemical composition of the bioprotected musts and wines, according to different settling routes. Their impacts on the organoleptic characteristics of wines were also studied. Methods and Results. A bioprotected must was subjected to 6 different maceration routes before AF (triplicates), varying the duration and temperature parameters. A temperature value ≤12°C was the main factor independently of the duration which allowed a good implantation of the bioprotectant. An increase of the maceration duration at 12°C led to browning of the must, without significant effect on the final color of the wine, which was felt as more “floral,” with more length in the mouth. Conclusions. The bioprotectant implantation and its effectiveness on the sensory profile of the wine was guaranteed at maceration temperature values lower than 12°C. Significance of the Study. This study participates in the improvement of the bioprotection management in white winemaking, with the guarantee of a positive impact of the prefermentation maceration without sulphites on the organoleptic profile of the wines.

Manipulating the severe shoot topping delays the harvest date and modifies the flavor composition of Cabernet Sauvignon wines in a semi-arid climate

This study aimed to mitigate the adverse effects of global warming by applying severe shoot topping (SST) to grapevines in a semi-arid climate. A three-year study (2018–2020) was performed to investigate the impact of SST on wine flavor composition. Results showed that SST effectively delayed the grape harvest date, which was more evident in the dry and warm vintage (7–11 d). SST significantly increased the concentration of myricetin-based flavonols in wines which were 18% higher than in untreated wines. Through orthogonal partial least squares discriminant analysis (OPLS-DA), SST wines were characterized by more abundant phenolic compounds and higher sensory scores. The carry-over effect of applying SST in consecutive years in the same vines could be reflected in wine color. The correlations among wine metabolites, color and aroma parameters, and sensory parameters were evaluated through multiple analyses. This study provided an idea for delaying grape ripening in a semi-arid climate.

Synergetic Effect of Metschnikowia pulcherrima and Lachancea thermotolerans in Acidification and Aroma Compounds in Airén Wines.

On the one hand, the species Lachancea thermotolerans is known for its high genetic diversity, allowing for the existence of strains that produce high concentrations of lactic acid. In contrast, the species Metschnikowia pulcherrima is renowned for its high enzymatic activity capable of producing aromatic esters during fermentation. By enhancing acidity and boosting the concentration of aromatic compounds, both species are currently used to enhance the organoleptic profile of wines. In this regard, ternary fermentations with M. pulcherrima and L. thermotolerans were carried out and the wines produced were further analysed with GC-FID, FTIR, and UV-Vis spectrophotometry. The outcomes showed that the species M. pulcherrima favored an increase in ethyl lactate (between 37 and 41 mg/L) along with an increased concentration of 2-phenylethyl alcohol (between 30 and 35 mg/L), whereas the species L. thermotolerans was able to produce 1 g/L of lactic acid in ternary fermentations. Additionally, pH levels were slightly lower in these fermentations and the color of the white wines produced showed less chemical oxidation as hue values were lower than the control. Finally, the ternary fermentations of L. thermotolerans and M. pulcherrima had higher overall rating in the tasting. In conclusion, ternary fermentations involving these two non-Saccharomyces species are suggested as a substitute for spontaneous fermentations in the production of wines from neutral varieties to express freshness more vividly. This biotechnology may be further favored by the possibility of applying emerging technologies for the removal of microorganisms in grapes and musts.

Effect of Pre-Fermentative Bentonite Addition on Pinot Noir Wine Colour, Tannin, and Aroma Profile

Pinot noir is a grape variety with thin grape skin, which means the extraction of colour and polyphenols is more challenging than other red grape varieties. The aim of this study was to investigate the impact of protein removal by adding bentonite prior to fermentation on Pinot noir wine composition. Four treatments were conducted, including the control without bentonite addition and Pinot noir wines produced with the addition of three different types of bentonites before cold soaking. The juice and wine samples were analysed for pathogenesis-related proteins, tannin, wine colour parameters, and aroma composition. The results showed that bentonite addition at 0.5 g/L had little impact on tannin and aroma compounds but more impact on wine colour, especially significantly higher level of SO2 resistant pigments observed in Na bentonite addition treatment. This study indicates the potential use of bentonite to modulate the Pinot noir juice composition that may facilitate the extraction of colour components from grape into juice, which plays an important role in colour stabilization in finished wine.

Impact of skin contact time, oak and tannin addition on the chemical composition, color stability and sensory profile of Merlot wines made from flash détente treatment

The ability to create differentiated red wine styles is key to meeting the diverse preferences of wine consumers. This study investigated the composition and style of Merlot wines made from flash détente (FD) treated must fermented with different levels of grape solids and skin contact time, and the potential for pre-fermentation addition of enotannin (0.4 g/L) or oak chips (4 g/L) to stabilize color. Off-skins fermentations, with or without addition of enotannin, gave wines with enhanced red fruit and confectionery characters (P = 0.0001), whereas addition of oak chips gave wines with prominent dark fruit, vanilla, toasty and allspice characters (P = 0.0001). However, additives did not improve wine color stability. Macerative fermentation of FD must enhanced dark fruit, body and astringency ratings (P = 0.0001), with FD wines exhibiting less intense green, savory and dusty notes (P = 0.0001). The study demonstrated solids removal had a greater influence on wine composition and style than skin contact time.

Potential applications of pulsed electric field in the fermented wine industry.

Fermented wine refers to alcoholic beverages with complex flavor substances directly produced by raw materials (fruit or rice) through microbial fermentation (yeast and bacteria). Its production steps usually include saccharification, fermentation, filtration, sterilization, aging, etc., which is a complicated and time-consuming process. Pulsed electric field (PEF) is a promising non-thermal food processing technology. Researchers have made tremendous progress in the potential application of PEF in the fermented wine industry over the past few years. The objective of this paper is to systematically review the achievements of PEF technology applied to the winemaking and aging process of fermented wine. Research on the application of PEF in fermented wine suggests that PEF treatment has the following advantages: (1) shortening the maceration time of brewing materials; (2) promoting the extraction of main functional components; (3) enhancing the color of fermented wine; (4) inactivating spoilage microorganisms; and (5) accelerating the formation of aroma substances. These are mainly related to PEF-induced electroporation of biomembranes, changes in molecular structure and the occurrence of chemical reactions. In addition, the key points of PEF treatments for fermented wine are discussed and some negative impacts and research directions are proposed.

Effects of Different Aging Methods on the Phenolic Compounds and Antioxidant Activity of Red Wine

In this study, oak barrels, glazed pottery altars, unglazed pottery altars, and stainless-steel tanks were selected as aging containers for red wine, and phenolic compounds and antioxidant activity were analyzed and compared. The color of red wine in unglazed pottery altars and glazed pottery altars changed to brick red and brownish yellow, respectively; the color of red wine in oak barrels did not change significantly; and color retention was best in stainless-steel tanks. The total content of anthocyanins and nonanthocyanin phenolic compounds was higher in the unglazed pottery altar group (227.68 mg/L and 288.88 mg/L, respectively) than in the oak barrel group (209.46 mg/L and 273.42 mg/L), the stainless-steel tank group (221.92 mg/L and 213.23 mg/L), or the glazed pottery altar group (74.71 mg/L and 204.43 mg/L). After aging, DPPH (1,1-diphenyl-2-picrylhydrazine free radical scavenging ability), I confirm. (ABTS+ free radical scavenging ability), and FRAP (a ferric ion-reducing antioxidant power reduction of Ion Ability) were decreased by 8.8%, 0.5%, and 17.1%, respectively, in the unglazed pottery altar group; by 15.2%, 1.7%, and 19.5%, respectively, in the oak barrel group; by 18.0%, 1.8%, and 20.0%, respectively, in the stainless-steel tank group; and by 18.7%, 4.2%, and 34.9%, respectively, in the glazed pottery altar group. In conclusion, antioxidative ability decreased less in the unglazed pottery altar group than in the other three groups, indicating that unglazed pottery altars retain antioxidant components in red wine well.

Comparison of the Effect of Cold Plasma with Conventional Preservation Methods on Red Wine Quality Using Chemometrics Analysis.

In this study, the effect of cold plasma (CP) on the physicochemical and biological properties of red wine was investigated in comparison with the effects of the conventional preservation method and the combined method. In addition, the effect of storage time after the application of each of the analyzed methods was evaluated. The study examined the effects of the different preservation methods on the pH, color, phenolic content, antioxidant activity and microbiological purity of the red wine. Chemometric analysis was used to discover the relationship between the preservation method used and wine quality. In the wine samples tested, a reduction in phenolic compounds and a decrease in antioxidant activity were noted after storage. This effect was mildest for preservation methods with the addition of potassium metabisulphite and those in which a mixture of helium and nitrogen was used as the working gas. On a positive note, the CP treatment did not affect the color of the wine in a way perceptible to the consumer: ∆E*—1.12 (He/N2; 5 min). In addition, the lowest growth of microorganisms was detected in the CP-treated samples. This indicates the potential of cold plasma as an alternative method to the use of potassium metabisulfite in wine production, which may contribute to its wider use in the alcohol industry in the future.

Developing novel oenological tannins from 44 plants sources by assessing astringency and color in model wine.

Oenological tannins are commercial natural products extracted from different botanical sources, which were widely reported as prominent contributors to wine quality. Research on wine quality affected by tannins extracts promoted the development of new oenological products with low cost and high accessibility. In the present study, the structure and concentration of tannin in polyphenol extracts, as well as their correlation with astringency and the color of model wine, was investigated by UV spectrophotometer, HPLC, fluorescence quenching, sodium dodecylsulfate-polyacrylamide gel electrophoresis, colorimeter and sensory evaluation. Resource extracts from 16 of 44 plants were screened as wine oenological tannins, according to the total polyphenol and total flavanol, as well as the intensity of astringency and bitterness. Polyphenols extracted from grape seeds and green tea were more effective in increasing the wine astringency compared to other plant tannins. Total flavanol content and tannin activity showed a strong correlation with wine astringency. Condensed tannins with mean degree of polymerization also exhibited strong color stability, and the concentrations of (-)-epigallocatechin were associated with the a* value, a negative qualitative factor for wine color. The present study provides new clues regarding the development of low-cost and highly accessible sources of polyphenol extracts and lays a theoretical foundation for the development of the oenological product. © 2022 Society of Chemical Industry.

Resistance of Single-shade Composites to Discoloration.

The aim of this study was to examine the color change of single-shade resin composites, which can be used for all tooth shades. In this study, samples were prepared using resin composites with single-shade (Omnichroma, Vitra Unique) and multishade composite systems (G-aenial A'Chord, Clearfil Majesty ES-2 Premium). The initial color values were measured with a spectrophotometer. Then, samples were kept in wine, coffee, black tea, and distilled water and color measurements were made after days 1, 7, and 30. Color change (ΔE00) and whiteness index (WID) values were statistically analyzed using a one-way analysis of variance (ANOVA) test (α=0.05). Single-shade resin composites showed more color change from wine, coffee, and black tea than multishade resin composites (p<0.001). Single-shade composites have a greater discoloration potential. Single-shade resin composites may show more color change from beverages than multishade resin composites, which may negatively affect clinical success.

Beneficial effects of bunch-zone late defoliations and shoot positioning on berry composition and colour components of wines undergoing aging in an organically-managed and rainfed Sangiovese vineyard

In the context of climate change, where high temperatures are frequent in the first phases of ripening, protecting grapevine bunches from solar radiation is essential for preserving berry composition and wine colour. The effects of bunch-zone late defoliations (DEFs) and “semi-ballerina” shoot positioning (SB) on vine physiology and grape and wine quality of organic cv. Sangiovese wines during storage were assessed in two contrasting seasons (2013 and 2014). The treatments altered neither vine physiology (leaf photosynthetic activity and stomatal conductance, stem water potential) nor vine phenology, yield, budburst and fruitfulness. Defoliations imposed at post-veraison (DEF I) and pre-harvest (DEF II), but not shoot positioning imposed at post-veraison, enhanced the concentration of berry skin flavonols at harvest, compared to an untreated control. Late defoliations and SB did not change berry weight, anthocyanins, soluble solids, pH or titratable acidity at harvest. The severity of Botrytis bunch rot was assessed in both seasons. In 2013, it was negligible regardless of the treatment. In 2014 (characterised by higher rainfall and lower average temperatures than in 2013), late defoliations (DEF I and DEF II), especially DEF I, and SB to a minor extent, limited the severity of Botrytis bunch rot. The oenological benefits of late defoliations and shoot positioning were observed during wine storage. These canopy management practices positively influenced wine components (polymeric pigments; namely short polymeric pigments) that might have a marked effect on the final colour intensity, without altering the basic chemical characteristics of the wine. When choosing the timing for carrying out defoliation in order to improve grape quality and bunch rot containment, the meteorological conditions should be properly considered. Our results may contribute to providing further recommendations for canopy management for grape growers who produce organic Sangiovese wines that undergo aging.

Ultrasound-assisted production of alcoholic beverages: From fermentation and sterilization to extraction and aging.

Ultrasound is sound waves above 20kHz that can be used as a nonthermal ''green'' technology for agri-food processing. It has a cavitation effect, causing bubbles to form and collapse rapidly as they travel through the medium during ultrasonication. Therefore, it inactivates microorganisms and enzymes through cell membrane disruption with physicochemical and sterilization effects on foods or beverages. This emerging technology has been explored in wineries to improve wine color, taste, aroma, and phenolic profile. This paper aims to comprehensively review the research on ultrasound applications in the winery and alcoholic beverages industry, discuss the impacts of this process on the physicochemical properties of liquors, the benefits involved, and the research needed in this area. Studies have shown that ultrasonic technology enhances wine maturation, improves wine fermentation, accelerates wine aging, and deactivates microbes while enhancing quality, as observed with better critical aging markers such as phenolic compounds and color intensity. Besides, ultrasound enhances phytochemical, physicochemical, biological, and organoleptic properties of alcoholic beverages. For example, this technology increased anthocyanin in red wine by 50%. It also enhanced the production rate by decreasing the aging time by more than 90%. Ultrasound can be considered an economically viable technology that may contribute to wineries' waste valorization, resource efficiency improvement, and industry profit enhancement. Despite numerous publications and successful industrial applications discussed in this paper, ultrasound up-scaling and applications for other types of liquors need further efforts.

Influence of Oxygen Management during the Post-Fermentation Stage on Acetaldehyde, Color, and Phenolics of Vitis vinifera L. Cv. Cabernet Sauvignon Wine.

Oxygen exposure is unavoidable and the impact of its management during the post-fermentation stage (PFS) on dry red wine is poorly investigated. This study was dedicated to the variation of acetaldehyde, color and phenolics of Cabernet Sauvignon dry red wine during five discontinuous oxidation cycles of four levels of controlled oxygen supply, which were carried out to simulate probable oxidation during the PFS. Free SO2 disappeared after the first, second and third oxidation cycles in wines with high, medium and low levels of oxygen exposure severally, but subsequent oxygen exposure below or equal to 2 mg O2/L per cycle had little effect while 3–3.9 mg O2/L per cycle dramatically facilitated acetaldehyde accumulation, which was accompanied by an enormous variation in color and pigments, especially when total oxygen consumption was above 10 mg/L. The utilization of clustered heatmap and partial least square regression demonstrated the feasibility of characterization of wine oxidation degree using the chemical parameters measured by UV-spectrophotometry. Oxygen exposure during the PFS should be emphatically controlled, and chemical indexes determined by the UV–spectrophotometric method can be used for a scientific and effective description of wine oxidation degree.

Encapsulation of phenolic compounds by spray drying of Ancellotta and Aspirant Bouchet wines to produce powders with potential use as natural food colorants

Ancellotta and Aspirant Bouchet, Vitis vinifera L., are wines with a high anthocyanin concentration that have been used to increase color in high-quality red wines. This work was focused on the encapsulation of Ancellotta (ANCE) and Aspirant Bouchet (AB) wines by spray drying and obtaining wine powders (WP) with a high concentration of phenolic compounds. Spray drying conditions were optimized and the phenolic compounds in the WP were characterized. All WP were evaluated for moisture content, water activity, color parameters, anthocyanins, and flavan-3-ols composition. There was no significant difference in total anthocyanins content of ANCE and AB WP when inlet air temperature increased from 135 to 145°C with a fixed carrier concentration of 8% (w/w) but a decrease in the total anthocyanins was observed when carrier concentration increased to 10% (w/w). Regarding color evaluation, ANCE and AB WP corresponded to the fourth quadrant of color space CIELAB indicating blue - red color (348–357°), characteristic of anthocyanins and wine. In general, the values of hue angle were not affected at higher percentages of carrier agent, consequently, an increase in the ratio carrier-wine did not lead to a dilution of material. These results indicate that inlet air temperature (in the selected range) did not influence the anthocyanin profile in the WP and has allowed for optimization of the conditions to obtain phenolic-rich colored powders with potential use as natural antioxidants and food colorants.

Идентификация кристаллов тартратных солей в составе осадка вин

Crystalline sediment of potassium hydrotartrate and calcium tartrate in wines is a major problem of wine industry. Reliable identification of crystals can establish the cause of their formation and facilitate appropriate technological solutions. The research objective was to study the morphological features of potassium and calcium salts of tartaric acid via microscopy.&#x0D; The study featured natural crystal sediments that developed in 105 samples of white and red wines over six months after the end of fermentation, as well as when crystallization was provoked by freezing. The microscopic examination involved a Micmed-5 optical microscope and a PHENOMproX scanning electron microscope. Identification of cations in the composition of crystals followed the method of energy-dispersive spectroscopy, as well as the method of quality reaction with sulfate-anion in acidic medium.&#x0D; Co-precipitation of colloidal substances was typical of potassium hydrotartrate. It violated the crystal lattice construction and determined the wine color, polymorphism (truncated ellipsoid → lanceolar → rhomboid → geometrically irregular shapes), surface roughness, and optical opacity. The expressiveness increased with the crystal growth (3–350 μm). Calcium tartrate demonstrated no evolutionary changes; it was morphologically uniform, colorless, and transparent. Its crystals had smooth faces and clear edges, regardless of their size (1–150 μm) and the chemical composition of wine.&#x0D; The research systemized the morphological features of tartrate crystals formed in wines. The obtained results are important for the technochemical control in the process of destabilization diagnosis. The data can be recommended for further studies in applied research laboratories and institutes.

Quantification of reduced and oxidized glutathione in wine by MALDI-TOF MS

Reduced glutathione (GSH) is one of the important antioxidants in the winemaking and aging process and it also regulates the color and flavor of wines. Accurate and rapid quantification of GSH is crucial in wine quality control. In this study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was demonstrated to quantify GSH and oxidized glutathione (GSSG) of wine in a high-throughput way. Quinoline-5,8-dione was used as a label to react with GSH, and the derivative of GSH, glutamate-cysteine-alanine, acted as the internal standard (IS). The quantitative decrease of GSH and the increase in GSSG were detected with a relative standard deviation of ≤ 5%, after the wines were exposed to air from one to seven days, and the concentration changes of GSH and GSSG were measured by simple dilution. All the results suggested the feasibility and potential of this method for wider applications in the quantification of GSH and GSSG.