Clarification And Filtration Research Articles

Starmerella bacillaris Strains Used in Sequential Alcoholic Fermentation with Saccharomyces cerevisiae Improves Protein Stability in White Wines

Haze can appear in white wines as a result of the denaturation and subsequent aggregation of grape pathogenesis-related (PR) proteins. Yeast cell-wall polysaccharides, particularly mannoproteins, represent a promising strategy to reduce the incidence of this phenomenon. The aim of this study was to evaluate the effects of 13 Starmerella bacillaris strains, in sequential fermentation with Saccharomyces cerevisiae, on wine protein stability of three white wines (Sauvignon blanc, Pinot grigio, and Manzoni bianco). The resulting wines were characterized in terms of their chemical composition, content of PR proteins and polysaccharides, and heat stability. In addition, the mannoprotein fraction was purified from six wines, five produced with S. bacillaris and one with S. cerevisiae EC1118 used as control. Generally, wines produced with S. bacillaris strains were more heat-stable, despite generally containing higher amounts of PR proteins. The increased heat stability of Starmerella wines was attributed to the stabilizing effect resulting from their higher concentrations of both total polysaccharides and mannoprotein fractions. In particular, for the most heat unstable wine (Manzoni bianco), the low MW mannoprotein fraction resulted to be the most involved in wine stability. The ability to produce wines with different heat stability was demonstrated to be strain-dependent and was more evident in the most unstable wines. By reducing fining waste, the use of S. bacillaris as an enological starter can be proposed as a new tool to manage wine protein stability for a more sustainable winemaking.

Impact of Lachancea thermotolerans on Chemical Composition and Sensory Profiles of Viognier Wines.

Viognier is a warm climate grape variety prone to loss of acidity and accumulation of excessive sugars. The yeast Lachancea thermotolerans can improve the stability and balance of such wines due to the partial conversion of sugars to lactic acid during alcoholic fermentation. This study compared the performance of five L. thermotolerans strains in co-inoculations and sequential inoculations with Saccharomyces cerevisiae in high sugar/pH Viognier fermentations. The results highlighted the dichotomy between the non-acidified and the bio-acidified L. thermotolerans treatments, with either comparable or up to 0.5 units lower pH relative to the S. cerevisiae control. Significant differences were detected in a range of flavour-active yeast volatile metabolites. The perceived acidity mirrored the modulations in wine pH/TA, as confirmed via “Rate-All-That-Apply” sensory analysis. Despite major variations in the volatile composition and acidity alike, the varietal aromatic expression (i.e., stone fruit aroma/flavour) remained conserved between the treatments.

Effect of Cold Stabilization Duration on Organic Acids and Aroma Compounds during Vitis vinifera L. cv. Riesling Wine Bottle Storage.

During the storage of wines in bottles, especially white wines, tartrate crystallization often occurs, which reduces the commercial value of the wines and therefore needs to be avoided by performing cold stabilization treatments before bottling. However, whether different cold treatment durations impact the quality of a wine’s aroma has not yet been of special concern. This research was conducted at an industrial scale to explore how cold treatments at −5.3 °C for 10 to 15 days impact the organic acids, aroma compounds, and sensory quality of Riesling dry white wines, and the variation was documented at the end of treatment, and at 6 and 12 months of bottle storage. The results showed that cold treatments significantly reduced tartaric acid concentrations and significantly affected the concentrations of most aroma components in the wines only after 12 months of bottle storage, including the main components of esters, norisoprenoids, terpenoids, and furfural. Moreover, the concentrations of some components showed an increasing trend with the bottle storage, especially 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN), the characteristic volatile of Riesling wine, suggesting that an acidic condition resulting from cold treatment might facilitate the conversion of some aroma precursors into volatiles. In conclusion, cold stabilization treatments, within limits, can improve tartaric acid stability and could promote the conservation of aroma compounds during bottle storage without adversely affecting the aroma profile of the wines.

Relative impact of oenological tannins in model solutions and red wine according to phenolic, antioxidant, and sensory traits

Oenological tannins (OETs) are winemaking processing aids used to facilitate stabilization and fining, to increase the antioxidant capacity, and to promote colour stability of grape juice and wine. A wide variability of pure or mix formulates are available for winemaking purposes, including hydrolysable tannins (gallotannins and ellagitannins), proanthocyanidins from grape skins and seeds (prodelphinidins and procyanidins), and from exotic wood (prorobinetinidins and profisetinidins). In this study, seventeen OETs pure and mix formulates were characterized in terms of polyphenolic content and antioxidant capacity in a model wine and in a red wine after one-month storage, as well as aroma, astringency, and bitterness sensory characteristics in water and red wine. Colour-related features were also analysed in the added red wine after one-month storage. For the first time, correlations among the obtained results in the different matrices were investigated to understand the most suitable OETs for winemaking applications. The results showed a great variability among the formulates studied in terms of phenolic content, which was strictly correlated to their antioxidant capacity. Regarding origin, hydrolysable tannins had the highest antioxidant ability, followed by exotic wood formulates. A strong and positive correlation was found in antioxidant capacity of OETs in model wine and red wine after one-month storage, in particular for ellagitannins, which confirmed also their ability to increase pigments polymerization. By contrast, quebracho tannins resulted the bitterest and most astringent when tasted in water (0.4 g/L), although in-mouth and aromatic descriptors of OETs tasted in water were not correlated with the ones of the added red wine. Therefore, the choice of OETs formulate and its optimal dose requires a characterization in terms of polyphenolic content and antioxidant capacity because these properties were well correlated with those of the added wines in a short storage period, whereas the sensory impact at oenological range doses is mainly dependent on wine features.

The production of preconditioned freeze-dried Oenococcus oeni primes its metabolism to withstand environmental stresses encountered upon inoculation into wine

Oenococcus oeni is the most resistant lactic acid bacteria species to the environmental stresses encountered in wine, particularly the acidity, presence of ethanol and phenolic compounds. Indigenous strains develop spontaneously following the yeast-driven alcoholic fermentation and may perform the malolactic fermentation whereby improving taste, aroma, and the microbial stability of wine. However, spontaneous fermentation is sometimes delayed, prolonged or incomplete. In order to better control its timing and quality, O. oeni strains are selected and developed to be used as malolactic starters. They are prepared under proprietary manufacturing processes to survive direct inoculation and are predominantly provided as freeze-dried preparations. In this study, we have investigated the physiological and molecular alterations occurring in O. oeni cells prepared by an industrial process that consists of preconditioning protocols and freeze-drying, and compared them to the same strain grown in a grape juice medium. We found that compared to cultured cells, the industrial production process improved survival under extreme conditions, i. e. at low pH or high tannin concentrations. In contrast, cultured cells resumed active growth more quickly and strongly than freeze-dried preparations in standard pH wines. A proteomic analysis showed that during the industrial production most non-essential metabolic processes are shut down and components of the general and the stringent stress response are upregulated. The presence of major components of the stress response facilitates protein homeostasis and physiological changes that further ensure the integrity of cells.

1H NMR and UPLC-HRMS-based metabolomic approach for evaluation of the grape maturity and maceration time of Touriga Nacional wines and their correlation with the chemical stability

Touriga Nacional is a well-adapted Portuguese grape variety in São Francisco River Valley (northeastern Brazil). Nevertheless, it has only been indicated to short-term consumption because of the lack of chemical stability, which is attributed to low grape acidity and incomplete phenolic maturity. Therefore, we used Ultra-Performance Liquid Chromatography coupled High-resolution Mass Spectrometry, Nuclear Magnetic Resonance and chemometrics (PCA and PLS-DA) to evaluate the grape maturity and maceration time on chemical composition of wines from two harvest seasons. Moreover, we investigated how these experimental factors could affect their chemical stability. Grapes maturity showed to be the main effect. Overall, phenolic acids and short-chain organic acids were found to be at higher levels in wines produced with unripe grapes from February and shorter maceration time (p < 0.05). Proanthocyanidins and other flavonoids were increased in wines macerated for longer time using overripe grapes harvested in July. Furthermore, stable wines were made from overripe grapes, which contained more galacturonic acid.

Impact of Cross-Flow and Membrane Plate Filtrations under Winery-Scale Conditions on Phenolic Composition, Chromatic Characteristics and Sensory Profile of Different Red Wines

Cross-flow microfiltration and membrane plate filtration are the main filtration processes used in wineries. However, the inherent compositional variability of red wines could affect the impact of these two filtration techniques on the final wine quality. Thus, this work aims to study, under winery-scale conditions, the impact of these two filtration processes on the turbidity level, phenolic composition, chromatic characteristics and sensory profile of red wine. For this purpose, three different Portuguese red wines with different initial phenolic contents were used. In this context, several methodologies were used to quantify the total phenolic composition, chromatic characteristics, individual anthocyanins and proanthocyanidins before and after filtration. The sensory profiles of the different red wines were also considered. The results indicated that each filtration process produced a substantial reduction in turbidity values and, consequently, an increase in wine clarification. In addition, the data obtained also indicated that both filtration techniques reduced the phenolic content of the different red wines that were studied. However, the impact of these two filtration options on wine characteristics (phenolic composition and sensory profile) was heterogenous, without a clear trend of differentiation between the wines depending on the type of filtration. Thus, this research points out evidence that the impact of the two filtration techniques that were studied is very dependent on the initial wine composition.

Monitoring of Sangiovese Red Wine Chemical and Sensory Parameters along One-Year Aging in Different Tank Materials and Glass Bottle

The aim of this research was to study how different tank materials affected the chemical composition and the sensory profile of a red wine during aging. For this purpose, a single varietal Sangiovese wine was aged at the same time by using different tank materials including stainless steel, epoxy-coated concrete, uncoated concrete, earthenware raw amphorae, and new and used oak barrels. Phenolic and volatile compounds, elemental content, tartaric stability, and sensory discriminant attributes of Sangiovese wine from the 2018 harvest were measured after 6 and 12 months of aging in tanks and 6 months in glass bottle (after the aging of 6 months carried out in each relevant container). The results showed that the different tanks significantly differentiated the wines on the base of all the chemical and sensory parameters considered. In particular, wines aged in earthenware raw amphorae and uncoated concrete registered a high content of polymeric pigments as the wine aged in the new oak barrel, resulting in materials that better promote the wine color stabilization. The same wines also showed the highest pH and tartaric stability, mostly likely related to the observed release of inorganic compounds from the tank material. Moreover, bottle aging enhanced the chemical and sensory differences between all the wines: they were characterized by a higher content of varietal volatiles such as norisoprenoids and terpenes, probably due to the reductive conditions in the bottle. The bottle also affected the perceived quality of the wines aged in concrete (uncoated and epoxy-coated) associated to the floral flavor, floral odor, sweetness attributes, and, to a lesser extent, acidity, while the ones aged in stainless steel and amphorae is associated to the berry jam odor.

The Effect of the Double Reasoned Maturation (DMR) Method on the Chemical Composition of the Juice and Wine of the Bianca Grape Cultivar

This paper aims to detect the effects of DMR (double reasoned maturation) method, and if it is able to increase the quality of Hungary’s most distributed white wine variety, Bianca. The resistant interspecific hybrid Bianca cultivar can accumulate high sugar content during ripening, but it is prone to drastic acid loss, which can lead to deficient microbiological stability of wines. The DMR method is suitable for achieving fruit with better sugar/acid ratio due to the shrinking of the berries. The DMR treatment was found to be a possible tool for avoiding rapid acid loss in Bianca juices. Early cutting of one-year-old wood and early harvest were found to be the ideal combination for increasing quality.

Comparison of a Rapid Light-Induced and Forced Test to Study the Oxidative Stability of White Wines.

The oxidation processes of white wines can occur during storage and commercialization due to several factors, and these can negatively affect the color, aroma, and quality of the wine. Wineries should have faster and simpler methods that provide valuable information on oxidation stability of wines and allow fast decision-making procedures, able to trigger suitable technological interventions. Using a portable prototype instrument for light irradiations at different wavelengths and times was considered and evaluated on sensorial, spectrophotometric, and colorimetric parameters of white wines. The sensorial analysis revealed that white and light blue were the most significant, after only 1 h of irradiation. The experimental results showed that hydrogen peroxide could enhance the effect of light treatment, allowing a contemporary evaluation of the oxidation stability of wine against light and chemical stresses. As expected, a good correlation (R2 > 0.89) between optical density at 420 nm and b* parameter was highlighted. The synergic effect of light and H2O2 was also studied on the hydrolyzable and condensed tannins’ additions to white wine. The proposed methodology could be used to evaluate the oxidative stability of white wines, but also to evaluate the effect of some oenological adjuvants on wine stability.

Improving effects of three selected co-pigments on fermentation, color stability, and anthocyanins content of blueberry wine

The effects of caffeic acid, syringic acid, and quercetin co-pigments on fermentation, color changes, and anthocyanins stability of blueberry wine were evaluated. The co-pigmented blueberry wines exhibited a higher alcohol and titratable acidity, and a lower sugar content. This was accompanied by a lower L* and a* and a greater b*, a significant shift in the λmax and an increase in absorbance value at λmax, altogether, indicating a darker and vivid bluish red color of blueberry wines. Total anthocyanins content in the wine samples with co-pigments were significantly higher with a greater stability after 20 days of post-fermentation. The malvidin glucoside and cyanidin glucoside exhibited the most stability in co-pigmented blueberry wines whilst none of the used co-pigments were able to protect cyanidin galactoside. We speculate that co-pigmentation with caffeic acid, syringic acid, or quercetin is an effective way to produce blueberry wine with a higher nutritional and sensory quality.

Instrumental assessment of the formation of the elemental composition of wines with various bentonite clays

The work is devoted to the study of the influence of clarification and stabilization of wines with bentonite clays (BT) on their elemental composition, which determines their varietal differences. Raw wine samples produced from grape varieties Cabernet Sauvignon, Merlot and Moldova in the Krasnodar Territory were clarified and stabilized with 32 BT samples of various degrees of dispersion and trademarks. The ICP-OES and ICP-MS methods were used to quantify 39 elements in 96 treated and 3 untreated wine samples, as well as BT samples. To establish possible mechanisms of metal exchange in the studied samples, a qualitative and quantitative phase analysis of the components was carried out, according to which BT were divided into four groups. The wine samples treated with BT of various groups had a different chemical composition, which differed from the initial ones in the concentration of almost all the determined elements. At the stabilization and clarification stages of wines with BT samples, a violation of the relationship between the elemental composition of wine, grapes and soil was observed. It was noted that when identifying marker elements determining the varietal affiliation of wine, it is necessary to take into account the contribution of BT to the formation of its elemental composition. Considering the contents of 16 isolated metals in the treated wine samples, the presence of cluster structures was established by the discriminant analysis and principal component analysis, indicating the preservation of intervarietal differences and intravarietal similarity after treatment with BT. BT did not change the varietal identity of wines, but influenced their elemental composition.

Microbial Xylanases: A Review

Enzymes play a key role in producing important and useful products in our daily life. They act as biocatalysts that increase the rate of chemical reactions. A category of enzymes known as xylanases are hydrolyzing enzymes that hydrolyze the -1,4-xylan, the principal constituent of hemicelluloses, into xylose sugar. Xylanases are categorized as endoxylanase, xylosidases, arabinofuranosidase, glucuronidase and esterases. The substrate xylan is highly expensive for enzyme production, so for reducing its cost, agricultural residues like wheat bran, rice bran, corn cobs, sugarcane bagasse, sawdust and oat bran etc. are used as substrate. Enzyme production can be carried out by using fermentation techniques through microorganisms such as fungi, yeasts, bacteria, actinomycetes etc. Xylanases are considered an important tool in industrial sectors like pulp and paper industry, textile industry, food and feed industry, bio-ethanol production and fruit juices and wine clarification.

A New Test of Filterability for Unprocessed Wines Evaluation of the Enzyme Efficiency

A new Test of Filterability has been developed. Measurements carried out with different types of wines indicate that the new filterability index is a useful tool for understanding and predicting the propensity to fouling of treated or untreated wines, e.g. with or without enzyme addition. The measurement method used in the Test of Filterability, requires only one type of membrane for all types of wine, and uses the same equipment as the traditional Fouling Index. Numerous trials have demonstrated that the filtration of wines is governed by standard blocking law. The definition of the new Test of Filterability, based on this filtration law, is proposed. The choice of membrane and the selection of the optimal pore size were based on the results of the experiments. Current methods used for the determination of fouling properties in wine filtration have been developed for the membrane filtration of small quantities of suspended matter. Enzyme treatment is a process often used in wine clarification. The new Test of Filterability indicates the best conditions for the filtration of all types of wines. The test is easy to implement and has been validated with various wines. This new Test of Filterability is an important tool for winemakers as it constitutes a simplified test of a wine's filterability. The new test may also be used to determine the filtration process that is best adapted to each wine while reducing the number of operations. The same approach may be adopted for the filtration of other liquids.

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.

Effect of Leaf Area Size on the Main Composition in Grape Must of Three Varieties of Vitis vinifera L. in an Organic Vineyard

The concentrations of sugars and acids are very important for the quality and the stability of wines. In addition, the proportion of the two main acids, i.e., tartaric acid and malic acid, is a significant factor for wine taste and stability. Over a period of three seasons in an organic vineyard, the influence of leaf area on the concentration of total soluble solids (TSS), pH, titratable acidity (TA), the concentration of tartaric acid and malic acid, and their mutual proportions were monitored. Vines of three varieties (‘Rhine Riesling’, ‘Pinot Gris’, ‘Sauvignon Blanc’) were treated using three different treatments (proportion of leaves removed 0%, 40%, and 70%). All varieties exhibited positive correlations between leaf area and TSS. In terms of relationships between TA and leaf area, ‘Sauvignon Blanc’ was the most sensitive variety. The highest differences between the individual variants were found for this variety. The tartaric to malic acid ratio displayed a significant seasonal effect, which was mostly more important than leaf area reduction. The size of the leaf area mainly affected the accumulation of sugars in the grapes, while content and ratio of acids was not affected so significantly. Therefore, leaf area regulation is one of the ways to optimize the composition of grapes in organic vineyards.

Haze Formation and the Challenges for Peptidases in Wine Protein Fining.

To meet consumer expectations, white wines must be clear and stable against haze formation. Temperature variations during transport and storage may induce protein aggregation, mainly caused by thaumatin like-proteins (TLPs) and chitinases (CHIs), which thus need to be fined before bottling of the wine. Currently, bentonite clay is employed to inhibit or minimize haze formation in wines. Alternatively, peptidases have emerged as an option for the removal of these thermolabile proteins, although their efficacy under winemaking conditions has not yet been fully demonstrated. The simultaneous understanding of the chemistry behind the cleavage of haze proteins and the haze formation may orchestrate alternative methods of technological and economic importance in winemaking. Therefore, we provide an overview of wine fining by peptidases, and new perspectives are developed to reopen discussions on the aforementioned challenges.

Influence of enzymative catalysis on technological parameters of apple juice production

The article provides data on the investigation of the effect of enzymatic catalysis on the technological parameters of apple juice production. Apples are distinguished by the presence of a heterogeneous high-molecular complex of biopolymers, which complicates their processing: it prevents juice output, hinders its clarification, filterability of wine materials and negatively affects the colloidal stability of wines. Enzymatic catalysis based on the action of microbial preparations, contributes in many respects to the successful solution of the problems of intensifying technological processes of fruit and berry raw materials processing and improving the quality of obtained products. Enzyme preparations of complex action, causing deep hydrolysis of high-molecular components of the peel and pulp of fruits, provide a more complete extraction of the liquid fraction, better clarification and filterability of juices. The foothill zone of Adygea has special soil and climatic conditions that affect the formation of physical and chemical characteristics of raw materials. Considering that apple tree occupies the first place in terms of planting area among fruit crops in the Republic of Adygea, an urgent task is to study the effect of enzymatic catalysis on technological properties of juices obtained during the processing of apples grown in these soil and climatic conditions. Enzyme preparations of complex action, recommended for the processing of fruit juices and wine materials, made in France and Germany, have been selected as objects of the research. The results of the studies on the use of enzyme preparations in the processing of apple juices, taking into account their influence on the juice yield and such technological parameters as the speed and quality of clarification, filterability and dynamics of alcoholic fermentation, have been presented. The effect of enzymatic catalysis on the mass concentrations of polysaccharides, starch, total nitrogen and phenolic substances has been studied. A higher hydrolytic activity of the Extrazyme enzyme preparation has been established, when added to the pulp; it contributes to the deep transformation of high-molecular substances and, as a result, to optimize the technological parameters of juice production

DCMC as a Promising Alternative to Bentonite in White Wine Stabilization. Impact on Protein Stability and Wine Aromatic Fraction.

Protein haze in white wine is one of the most common non-microbial defects of commercial wines, with bentonite being the main solution utilized by the winemaking industry to tackle this problem. Bentonite presents some serious disadvantages, and several alternatives have been proposed. Here, an alternative based on a new cellulose derivative (dicarboxymethyl cellulose, DCMC) is proposed. To determine the efficiency of DCMC as a bentonite alternative, three monovarietal wines were characterized, and their protein instability and content determined by a heat stability test (HST) and the Bradford method, respectively. The wines were treated with DCMC to achieve stable wines, as shown by the HST, and the efficacy of the treatments was assessed by determining, before and after treatment, the wine content in protein, phenolic compounds, sodium, calcium, and volatile organic compounds (VOCs) as well as the wine pH. DCMC applied at dosages such as those commonly employed for bentonite was able to reduce the protein content in all tested wines and to stabilize all but the Moscatel de Setúbal varietal wine. In general, DCMC was shown to induce lower changes in the wine pH and phenolic content than bentonite, reducing the wine calcium content. Regarding which VOCs are concerned, DCMC produced a general impact similar to that of bentonite, with differences depending on wine variety. The results obtained suggest that DCMC can be a sustainable alternative to bentonite in protein white wine stabilization.

Effects of oenological tannins on aroma release and perception of oxidized and non-oxidized red wine: A dynamic real-time in-vivo study coupling sensory evaluation and analytical chemistry

Addition of oenological tannins claims to have a positive impact on wine stability, protection from oxidation and likely sensory persistence. However, their role on red wine aroma during oxidation is controversial. The present study aims at investigating the effect of addition of oenological tannins on wine flavour (mainly aroma) before and after air exposure. Temporal Dominance of Sensations, a dynamic sensory evaluation, was coupled with a dynamic chemical measurement (nosespace analysis) using a Proton-Transfer-Reaction Mass-Spectrometer connected to the nasal cavity of 17 assessors. Results showed that the oxidation of a non-oaked Pinot Noir red wine decreases the fruity aroma dominance and increases the maderised and prune one. A contextual decrease of the fruity ethyl decanoate and increase of oxidative Strecker aldehydes are observed. Ellagitannins but not proanthocyanidins preserved perception of fruitiness and prevented increase of maderised notes. Moreover, ellagitannins increase the aroma persistence mainly in the non-oxidized wine.