Yeast autolysis in sparkling wine – a review

Sparkling wine produced by the traditional méthode champenoise requires a second in-bottle alcoholic fermentation of a base wine, leading to the sparkling wine. This second fermentation is followed by prolonged ageing in contact with yeast cells (lees). The autolysis of yeast occurs during the ageing of sparkling wines. During this process, the yeast releases different compounds that modify the organoleptic properties of the wine. The ageing period is required to give these wines their roundness and characteristic aroma and flavour. Autolysis products also influence the foaming properties of sparkling wine. Yeast autolysis is characterised by the hydrolysis of intracellular biopolymers by yeast enzymes activated after cell death. This results in the release of low molecular weight products. This article reviews the recent advances in understanding the yeast autolysis mechanism, the factors affecting autolysis, the nature of the released compounds and their effects on sparkling wine quality.     

Exploring 2-aminoacetophenone contents in sparkling wines based on analytical data and statistical modelling

The influence of the second fermentation step on sparkling wine aroma was investigated with respect to the content of 2-aminoacetophenone (AAP) as an indicator substance for the atypical ageing off-flavour (ATA). AAP contents of aged sparkling wines and their corresponding base wines (Riesling and Chardonnay variety) were determined by means of multidimensional gas chromatography using a stable isotope dilution assay. The majority of sparkling wines were lower in AAP in comparison with their corresponding base wines. Explorative and predictive statistical analyses of the resulting AAP content in sparkling wines were performed concerning the influence of the parameters lees contact time, yeast strain, base wine AAP concentration and total phenolic contents. Both statistical approaches yielded good fits with AAP concentration of the base wine being the predominant factor. Although it was possible to explain the changes in AAP concentrations on the basis of how total phenolics changed during second fermentation, predicted AAP trends did not hinge upon the amount of total phenolics present in a base wine. Unpressurised model fermentations were a promising technological alternative to study the development of AAP in sparkling wines. Altogether, this study presents a multidisciplinary approach to master the challenging task of ATA risk assessment in base wines, which at present rather accesses the sparkling wine producer’s individual experience.     

Influence of the use of bentonite as a riddling agent on foam quality and protein fraction of sparkling wines (Cava)

This paper studies how the use of bentonite to facilitate the riddling process affects the foam properties and the protein fraction of sparkling wines (Cava). In all monovarietal sparkling wines (Macabeu, Xarel.lo, Parellada, Chardonnay and Pinot Noir), the addition of bentonite produced a statistically significant diminution of the Mosalux parameters (HM and HS). This depreciation of the foam quality may be attributed to the direct interaction of bentonite with wine proteins. Concretely the use of bentonite caused a diminution of more of 80% of total the soluble protein. Gel filtration by FPLC showed that bentonite particularly affected the 60 kDa and 20–30 kDa protein fraction. The high molecular fraction, on the other hand, was not affected.     

The use of thaumatin and bovine serum albumin as proteins in model wine solutions in bentonite fining

This study examined the viability of using thaumatin and bovine serum albumin (BSA) as proteins in model wine solutions for bentonite fining studies and compared them with unfined New Zealand sauvignon blanc (SB) wine. Bentonite fining trials were performed on model wine solutions and unfined SB wines (pH range 3.5–4.3). Thaumatin was more readily adsorbed onto bentonites of all types than BSA and its adsorption onto bentonite was less affected by the pH of the solution. Specifically, the amount of BSA adsorbed onto bentonite decreased significantly as the pH of the solution approached the isoelectric point (pI) of BSA while thaumatin was adsorbed at that pH due to its higher pI. Changing pH affected protein adsorption of real wine less noticeably than of BSA and thaumatin, and decreasing pH increased protein adsorption in contrast to the model solutions. Neither of the model solutions can fully represent the response of real wine to bentonite fining but they are simple and cost effective to prepare and reacted to changes in bentonite concentration similar to real wine. Thaumatin is potentially a better protein to use in simple model solutions for wine stabilisation studies like filtration where molecular weights are important consideration.     

Antioxidant Properties of Sparkling Wines Produced with β-Glucanases and Commercial Yeast Preparations

The aim of this study was to evaluate the in vitro antioxidant potential of sparkling wines produced with β-glucanases, autolysated yeasts, yeast cell walls, and purified mannoproteins. Total antioxidant capacity (measured by 2,2-diphenyl-1-picrylhydrazyl [DPPH] radical-scavenging method and ferric reducing antioxidant power [FRAP] assay), and hydroxyl radical-scavenging activity (HRSA) were higher in the wine samples with coadjuvants (in relation to the control wine). The highest values of antioxidant activity were achieved with purified mannoproteins and, in lesser extent, with β-glucanases. Neutral polysaccharides and total proteins were highly and positively correlated with DPPH, FRAP, and HRSA assays. However, correlations between the levels of each different phenolic family and antioxidant and radical-scavenging activities were not found. β-Glucanase and commercial yeast preparations can be excellent coadjuvants to increase the antioxidant properties of sparkling wines. Practical Application: β-Glucanase and commercial yeast preparations can be excellent coadjuvants to increase the antioxidant properties of sparkling wines. The suggested improvement has significant implication for the production of high added value sparkling wines.     

Changes in chromatic characteristics and phenolic composition during winemaking and shelf-life of two types of red sweet sparkling wines

The Brachetto variety is the most important aromatic red grape used for the production of sweet sparkling wines in Italy. The phenolic composition and chromatic characteristics were studied in base and red sweet sparkling wines made from this variety. The present work represents the first study on sparkling wines manufactured with Brachetto grapes. The amount of pigments extracted in the base wine was low as a consequence of the necessity for short maceration time (48 h) and low alcohol content (< 3.5% v/v). The second fermentation (prise de mousse) caused a pigment content decrease, accompanied by both a color intensity decrease and a tonality increase. In terms of phenolic compounds and chromatic characteristics, lightly sparkling wines (final bottle pressure < 1.7 bar) agreed with fully sparkling wines (final bottle pressure > 3.0 bar) at the end of the second fermentation and, therefore, the chromatic quality was independent on the winemaking methodology used, excepting for lightness and color intensity.Response surface methodology was applied to predict the effect of two independent variables, namely time and temperature of storing, on the phenolic composition and chromatic properties in both lightly and fully sparkling wines. So, it is possible to evaluate the development of two types of sweet sparkling wines during their ageing in bottle and their commercial shelf-life. A central composite design (CCD) and response surface methodology (RSM) were used for this purpose. Quantitative changes were observed in the color parameters. Although the time variable strongly influenced them, the two sparkling wines were stable enough only at low temperatures after 12 months of ageing. During the wine ageing in bottle, an increase in the formation of polymeric red pigments can be suggested taking into account the losses observed in monomeric anthocyanins. The results obtained showed that the color of fully sparkling wines was more stable than that of lightly ones and, therefore, the shelf-life of the former ones could be longer.     

Influence of yeast strain,immobilisation and ageing time on the changes of free amino acids and amino acids in peptides in bottle‐fermented sparkling wines obtained from Vitis vinifera cv. Emir

This paper reports the influence of yeast strain, immobilisation and ageing time on the free amino acids and amino acids in peptides of sparkling wine made by the traditional method from the Emir grape variety over a period of 365 days in vintages 2004 and 2005. Four sparkling wines were obtained from the same base wine using yeast strains (both immobilised and free Saccharomyces bayanus and Saccharomyces oviformis). The analysis of variance and cluster revealed that there were significant differences between free amino acids and amino acids in peptides due to ageing time. However, the yeast strain affected most of the free amino acids and amino acids in peptides in only the 2004 vintage. The total amount of free amino acids was higher in the wine made with the S. oviformis compared to S. bayanus. Furthermore, there were no significant differences between the use of immobilised and free yeast in cases of free amino acids and amino acids in peptides.     

Chemical compounds and mechanisms involved in the formation and stabilization of foam in sparkling wines

The visual properties of sparkling wine including foam and bubbles are an indicator of sparkling wine quality. Foam properties, particularly foam height (FH) and foam stability (TS), are significantly influenced by the chemical composition of the wine. This review investigates our current knowledge of specific chemical compounds and, the mechanisms by which they influence the foam properties of sparkling wines. Grape and yeast proteins, amino acids, polysaccharides, phenolic compounds, organic acids, fatty acids, ethanol and sugar are examined with respect to their contribution to foam characteristics in sparkling wines made with the Traditional, Transfer, and Charmat and carbonation methods. Contradictory results have been identified that appear to be due to the analytical methods used to measure and quantify compounds and foam. Biopolymer complexes are discussed and absent knowledge with regards to thaumatin-like proteins (TLPs), polysaccharides, amino acids, oak-derived phenolic compounds and organic acids are identified. Future research is also likely to concentrate on visual analysis of sparkling wines by in-depth imaging analysis and specific sensory analysis techniques.     

Influence of the elaboration process on the peptide fraction with angiotensin I-converting enzyme inhibitor activity in sparkling wines and red wines aged on lees

The influence of some variables on the manufacturing process for sparkling and red wines on the angiotensin I-converting enzyme inhibitory (ACEI) activity has been studied. Ageing on lees significantly influenced the angiotensin I-converting enzyme inhibitor activity in sparkling wines. It reached maximum values at 9 months, decreasing afterwards. In red wines, the ACEI activity also increased in the wines aged on lees. In both wines, hydrophobic peptides were responsible for the ACEI activity. These peptides would make a much greater contribution to the total activity if present in higher proportions. It would therefore be advantageous to increase their concentrations in wines, either by using starting materials with high initial peptide contents or by using a highly autolytic yeast, giving a greater degree of hydrolysis of wine proteins, and higher concentrations of peptides with ACEI activity.     

Identification of 5-hydroxymethyl-2-furfural (5-HMF) in Cava sparkling wines by LC-DAD-MS/MS and NMR spectrometry

The aim of this study was to elucidate the structure of a potential ageing marker for Cava sparkling wine. In order to clarify the structure of this compound, NMR spectroscopy and hyphenated UHPLC-DAD-MS/MS techniques were used. We identified the hitherto unknown compound as 5-hydroxymethyl-2-furfuraldehyde (5-HMF). This is the first time that this compound has been reported in sparkling wines. A survey, based on the analysis of 80 commercial sparkling wines, showed that 5-HMF is present between 0.25 and 12.81 mg/L, and is compared with those reported for other types of wine. Hypothetical origin of 5-HMF in Cava sparkling wine is discussed.     

Partial characterization of peptides from red wines. Changes during malolactic fermentation and ageing with lees

The peptide fraction of an industrially manufactured red wine has been studied during malolactic fermentation, carried out in stainless-steel tanks or in the barrel and ageing in the barrel, with or without lees, for 12 months. Peptides were fractionated using Sephadex LH-20 and Cosmosil 140 C₁₈-OPN columns, giving two fractions in relation to peptide polarity. The most important changes were detected during malolactic fermentation and during the ageing in barrel with lees. The peptides present in the wine could be glycopeptides from grape or yeast. Most amino acids in the most polar peptides were aspartic acid and/or asparagine, glutamic acid and/or glutamine, serine, glycine, α-alanine and tyrosine and, in the less polar fraction, were glycine, α-alanine and leucine. The amino acid distribution is most different in the most polar fraction, among the studied wines, owing to autolysis and hydrolysis of the polypeptides and proteins.     

Biotechnologies in sparkling wine production. Interesting approaches for quality improvement: A review

Sparkling wines are produced by a secondary fermentation of a base wine followed by a prolonged ageing in contact with lees. In the traditional method, the refermentation takes place in the same bottle used for market distribution. The autolysis of yeasts occurs during the ageing of sparkling wines, thus causing the release of many parietal and cytoplasmic compounds which have a great influence on sparkling wine’s quality. The modern technologies for the production of sparkling wine are very different from the one developed by Abbot Dom Pierre Pérignon in the 17th century. Over the years, many advances have been made, this paper aims at reviewing the recent knowledge in the application of biotechnologies for the improvement of sparkling wine’s quality, in particular the factors affecting foaming properties and sensory qualities. Future perspectives and trends are also considered.     

Effect of the addition of β-glucanases and commercial yeast preparations on the chemical and sensorial characteristics of traditional sparkling wine

Sparkling winemaking is an increasing industry in Castilla y León region of Spain. Several trials have been made to improve the techniques in order to offer better products to the market. This study focuses on the evaluation of the influence of different co-adjuvants in the sparkling winemaking process (β-glucanases, autolysated yeasts, yeasts cell walls and purified mannoproteins) by measuring different oenological parameters at 3, 6 and 9?months of ageing after the secondary fermentation. Both physicochemical and sensorial analyses are considered in order to reveal the incidence of these co-adjuvants in the final product. A consumers study has also been carried out with the aim of knowing the possible impact of the co-adjuvants in the market of the so elaborated sparkling wines. β-Glucanases seem to increase the ageing characteristics of the sparkling wines, while yeast derivatives (yeast cell walls and yeast autolysates) improve their fruity and flowery character.     

Preventing protein haze in bottled white wine

Slow denaturation of wine proteins is thought to lead to protein aggregation, flocculation into a hazy suspension and formation of precipitates. The majority of wine proteins responsible for haze are grape‐derived, have low isoelectric points and molecular weight. They are grape pathogenesis‐related (PR) proteins that are expressed throughout the ripening period post véraison, and are highly resistant to low pH and enzymatic or non‐enzymatic proteolysis. Protein levels in un‐fined white wine differ by variety and range up to 300 mg/L. Infection with some common grapevine pathogens or skin contact, such as occurs during transport of mechanically harvested fruit, results in enhanced concentrations of some PR proteins in juice and wine. Oenological control of protein instability is achieved through adsorption of wine proteins onto bentonite. The adsorption of proteins onto bentonite occurs within several minutes, suggesting that a continuous contacting process could be developed. The addition of proteolytic enzyme during short term heat exposure, to induce PR protein denaturation, showed promise as an alternative to bentonite fining. The addition of haze‐protective factors, yeast mannoproteins, to wines results in decreased particle size of haze, probably by competition with wine proteins for other non‐proteinaceous wine components required for the formation of large insoluble aggregations of protein. Other wine components likely to influence haze formation are ethanol concentration, pH, metal ions and phenolic compounds.     

Protein haze in bottled white wines: How well do stability tests and bentonite fining trials predict haze formation during storage and transport?

Based on work undertaken over 30 years ago, most Australian winemakers use a heat test (80^oC for six hours) to check white wines for protein stability. Some winemakers consider that this test is too severe, resulting in wines being over-fined with bentonite. This paper presents the results of a study comparing the predictive ability of this test, assessed either by eye, by nephelometry or by optical density, with that of two alternative assays (80^oC for 2 hours and the Bentotest), through the use of storage trials of 8 wines designed to mimic commercial conditions of transport and storage of wine. One of the 8 unfined wines failed to develop haze even under the more severe storage conditions of this study (35^oC for a month or fluctuating between 20^oC and 35^oC for 8 days) and only 6 of the 8 unfined wines developed haze under 'best practice' storage conditions (13^oC–17^oC for 16 months). All the wines fined with bentonite at dosage rates determined by the three predictive tests used in the main part of this work remained bright in bottle after storage trials at 13^oC–17^oC for 16 months, 35^oC for 1 month or fluctuating between 20^oC and 35^oC for 8 days. Therefore the least severe stability test, heating at 80^oC for 2 hours, which generally indicated lower dosage rates in this study, accurately predicted short to medium term stability for these wines under these storage conditions.     

The effect of nitrogen addition on the fermentative performance during sparkling wine production

The transformation of must to wine is influenced by several factors, including the nitrogen composition of the grape must, which has an important impact on yeast growth, fermentation kinetics and the organoleptic properties of the final product. In the production of sparkling wine by the traditional method, a second fermentation takes place inside the bottle, followed by yeast autolysis. Before their inoculation, yeasts cells must be adapted to the wine by the process known as pied-de-cuve. The aim of this study is to determine how nitrogen composition both in the pied-de-cuve and the base wine, affects the development of the second fermentation. This effect was analyzed in three different strains and at two different fermentation temperatures (12 and 16 °C). The results indicate that the nitrogen intake during the pied-de-cuve is crucial for the development of the second fermentation, with strain-dependent nutrient preferences during this phase. The addition of organic nitrogen in this phase can enhance the second fermentation. However, the addition of nitrogen to the base wine, had little effect on fermentation kinetics, indicating that either the residual nitrogen of the wines (< 30 mg N/l), or the nitrogen taken up during the pied-de-cuve, was sufficient to cover the low nitrogen requirements during the second fermentation, and to ensure the good development of this process. The base wine and the temperature had also strong effects on the fermentation length and development. To optimize sparkling wine production, all factors involved in the second fermentation should be considered, although the interactions between base wine, temperature and yeast strain have the strongest effect on fermentation kinetics.     

Effect of using bentonite during fermentation on protein stabilisation and sensory properties of white wine

The bentonite use to remove proteins from white wine is a widespread practice that prevents protein haze formation after bottling. However, an excess of bentonite can have negative effects on both the aromatic profile of young white wines and the quality of the foam of sparkling wines. Therefore, the optimisation of bentonite amount to be used and the moment of its application during winemaking to minimise wine quality losses are of great interest for winemakers. This paper analyses how applying an equal bentonite dose at different stages (must clarification; beginning, middle and end of fermentation) on two scales (industrial and pilot) affects the protein content and stability, physical–chemical characteristics, aromatic profile and foam quality of the obtained wines. No important differences in the oenological parameters were observed between industrial and pilot scales, whereas the scale of the experimental treatments affected protein stability, aroma composition and foam quality of the wines.     

Autolytic capacity and foam analysis as additional criteria for the selection of yeast strains for sparkling wine production

This study proposes a selection methodology for secondary fermentation yeast strains for the production of sparkling wines. It began with 34 different yeast strains, mainly of the Saccharomyces cerevisiae species. The selection methodology was divided into four consecutive stages: (1) a study of the fermenting capacity of the strains under secondary fermentation conditions; (2) analysis of the most important enological characteristics of the strains; (3) a study of the autolytic capacity of the yeast; and (4) analysis of the foaming properties of the autolysates obtained. Following this methodology, three strains were selected, with which three sparkling wines were produced by the Champenoise method. Industrial sparkling wines were also produced with the commercial strain EC-1118, used as a control in this study, and with strain J, from the collection of the winery where the sparkling wines were prepared. The wines thus obtained were aged for 12 months in presence of the yeast. The findings of the sensory analysis indicated that all of the sparkling wines were good quality.     

Charakterisierung der elektrischen Eigenschaften und der Molmassen der Eiweißstoffe von Weißweinen

Characterization of the electrical properties and of the molecular weights of the proteins of white wines The electrical properties and the molecular weights of the proteins of the dry white wine Dimjat were investigated. The protein substances of the wine are aggregates consisting of 4 monomer proteins with molecular weights between about 28000 and 160000. The protein with the lowest molecular weight represents the major part. There are different reasons for the aggregation. This causes different properties of the aggregates and determines their reactions during the technological treatment. The protein fractions of the untreated wine have isoelectric points between 3.8 and 5.8. The protein-clouding is mainly caused by the protein-fractions with lower isoelectric points and lower molecular weights. The protein stability of the wine can therefore only be attained by such a technological treatment that leads to the removal or quantitative reduction of those protein fractions which are responsible for clouding. The protein stability is reached by the bentonitetreatment while the other treatments (heat, cold, and potassiumhexacyanoferrate (II)) we have examined were not successful.     

Release of nitrogen compounds to the extracellular medium by three strains of Saccharomyces cerevisiae during induced autolysis in a model wine system.

To detect differences among three strains of Saccharomyces cerevisiae used in the manufacture of sparkling wines and to study the changes in nitrogen compounds during autolysis, a model wine system was used. Significant differences were observed between the mean values of the autolytic capacity of the three strains. The amount of nitrogen (total, protein, peptide and amino) present in the autolysates and the concentration of most free amino acids was significantly affected by the strain. These findings suggest that the strain of yeast used in the manufacture of sparkling wines can play an important role in the aging process and can affect final composition.