Winemaking Update

Number 1 – 2014

NEWS FLASH

❖ The Lalvin ICV oKay® winemaking yeast received an Innovation Award at the SITEVI 2013 international exhibition. Lalvin ICV Varietal Aromas oKay® is the result of collaborative research by the scientific group of the Institut Coopératif du Vin (ICV), Lallemand, SupAgro Resulting from and INRA Montpellier. The innovation relies on successive back-crosses between a particularly effective yeast strain from a wine- Alcoholic and Malolactic making point of view and a yeast present- ing a very low capacity for producing such sulphur compounds as H2S and SO2. The Fermentations outcome is Lalvin ICV oKay®, which com- bines excellent fermentation capacity with very low SO2, H2S and acetaldehyde production. Lalvin ICV oKay® is recommended he interaction between microorgan- for aromatic white and rosé wines, where isms and the grape must is a complex it reduces volatile acidity levels, reveals T mechanism involving a multitude of aromatic esters and enhances freshness and substrates and products, including some that balance on the palate. have major sensory impacts. The nutrients ❖ The Lallemand Wine App is now com- present in the grape must (e.g., carbon, patible with iPad and Android devices. oxygen, nitrogen, sulphur and phosphorus Integrating all the functions offered for the compounds, vitamins, minerals and trace iPhone, the iPad and Android versions of elements) create the conditions necessary to the application put all the information you ensure the proliferation of microorganisms. need regarding Lallemand fermentation Particularly, microorganisms use the sugars products – from wine yeast and bacteria, to and amino acids, which have the metabolic their nutrients, protectors and enzymes – at effect of producing multiple metabolites from non-volatile esters (mostly polyols and your fingertips and help you make the best acids) and volatiles esters (e.g., alcohols, selection. aldehydes and ketones, fatty acids, sulphur and phenols), which also impact the aroma Figure 1. Carménère varietal and the “bouquet du vin” (Swiegers et al. of Muscat of Alexandria and Muscat Rosé WINEMAKING UPDATE 2005). The microorganisms interact with, revealed that these varietals are high in notably, the various aroma precursors pres- aglycones from the terpene family, as well WINEMAKING UPDATE is published by ent in the grape by targeting, more specifi- as C13-norisoprenoids, which confer flo- Lallemand to inform oenologists and wine- cally, the glycosides, conjugated cysteine and ral notes. Carménère (figure 1), the vari- making staff about the latest news and the phenolic compounds (Eglinton et al. etal emblematic of Chile, is high in C13- applications arising from research. To request 2004, and Dillon et al. 2004). norisoprenoid precursors, which encourage previous issues, or to send your questions or This issue of Winemaking Update summarizes the development of a rich aroma profile. comments, contact us at: the XXIVes Entretiens Scientifiques Lallemand. The influence of the terroir on the aroma Sigrid Gertsen-Schibbye These scientific meetings, held in 2013, dis- potential of Sauvignon Blanc grapes was also Lallemand Scandinavia U.K. cussed the impact of wine yeasts and bacteria shown. For example, in the Casablanca val- Bredstrupvej 33, 8500 Grenaa, Denmark on varietal aromas. ley (a temperate climate and later harvest), [email protected] produces grapes that were two and four times 1. The Aromatic Potential of +45 5357 2280 higher in 4-methyl-4-mercaptopentanone Warm Climate Wines (4MMP) and 3-mercapto-hexanol (3MH) The technical information in WINEMAKING Professor Eduardo Agosin, from the than those of Curicó valley, where it is very UPDATE is true and accurate at the time of Pontificia Universidad Católica de Chile, hot and vines are planted very densely. publication. Due to the great diversity of presented a summary of his research team’s Other research has revealed that mechani- winemaking operations, all information and work on aroma precursors. Yellow Muscat cal harvesting causes a greater loss of aroma advice is provided with no guarantee or and Early White Muscat, two rather rare precursors than hand harvesting. At the formal engagement. Lallemand products are varieties in northern Chile, where Pisco pre-fermentation stages, the thiol precursors widely available through distribution net- (a young brandy with a fruity nose) is continue to degrade (figure 2). By compar- works. To find your local distributor, contact produced, are especially rich in terpene ing the measurements taken on the grapes at us at the above address. precursors. In the same region, the study of their delivery to the winery and in the final aroma potential on more than 50 samples www.lallemandwine.com@ Continued in space and time and what links them to the vines and wines, Professor Goddard proposes Free thiols Bound thiols Loss sampling procedures, statistically useful tests and appropriate analysis techniques. 100% 25% Figure 3 outlines observations from research 80% 34% by Gayevskiy and Goddard (2012) on six 45% vineyards located in three regions in northern 60% New Zealand. During this study, 1,566 colo- nies were identified and underwent analysis 40% for similarities (ANOSIM), which revealed

Odour Units that, objectively, for the 2010 vintage ran- 20% domly sampled fungal communities from ripe Chardonnay grapes showed a much greater 0% difference than would be expected by chance Delivery Pressing Racking Fermentation (R values are significant according to pairwise -20% comparisons). The biodiversity of microorganisms, linked to different regions and ter- Figure 2. Evolution of free and bound 3-mercapto-hexanol (3MH), as a percentage of total 3MH at delivery roirs, is still to be explored as much remains to the winery and during different stages of winemaking with Sauvignon Blanc grapes from Casablanca (2006 unknown. harvest) 3. Influence of Enzymes on the Aroma Typicity of Touriga wine, immediately after fermentation, we can 2. How to Exploit the Microbial Nacional see that only 2% to 5% of the initial level of active and odorant thiols remain in the final Ecosystem of the Wine The “bergamot” aroma signature of the wine. The level of the thiol precursors in the Professor Matthew R. Goddard, from the Touriga Nacional varietal is attributed to ter- grape transforming into free thiols is very low. University of Auckland, New Zealand, pre- penol, linalool and their acetates. Research Even though the yeasts, during fermenta- sented concepts and techniques from the by Frank Rogerson and Charles Symington tion, release thiols, the concentration varies ecology of microorganisms, explaining their (Symington Family Estates, Portugal) showed considerably from one strain to another, and particular interest in the field of oenology. the interest of pectolytic enzyme prepara- we observe a loss of 25% to 45% of the initial Although we have considerable knowledge tions rich in ß-glucosidase activity on the value. Understanding the evolution of the about different strains of Saccharomyces cere- level of key odorant molecules of Touriga thiol precursors at the pre-fermentation stage visiae, there is still much to learn about the Nacional grapes. The red wines treated with and during alcoholic fermentation (AF) is phenotypic and genetic diversity of yeasts, as these preparations present a greater floral essential to optimizing their impact on the well as their distribution in space and in time. and citrus aroma complexity, which is main- final quality of the Sauvignon Blanc wines, For example, are the yeast species associated tained throughout aging in bottles for 2.5 much more than seeking to increase their with vines and wines the same in every region years. These results suggest that not only concentration in the grape. of the world? If not, how and to what extent the terpenols, but other aglycone precursors do they differ from one region to another? as well, are released and play an important Are yeasts involved in defining terroir? To role in the aroma complexity of the vari- better understand the distribution of yeasts etal. Winemakers should learn to master the

800 700 600 500 400 300 200 100 PDMS µg/L equivalent to DMS/L to PDMS µg/L equivalent 0

Strain 6 Strain 5 Strain 6

Syrah must Yeast strain 5

Strain 5 + Fermaid E Strain 6 + Fermaid E Strain 5 + Fermaid E Strain 6 + Fermaid E Synthetic must MS120

Figure 3. Outline of observations from the study Figure 4. Influence of the addition of Fermaid E on the consumption of potential dimethyl sulphide by by Gayevskiy and Goddard (2012) on six vineyards different strains of yeast during alcoholic fermentation located in three regions in northern New Zealand 4.5

4.0 a 3.5 ab

3.0 bc bcd 2.5 cde 2.0 def def efgh defg 1.5 fghi efghi efghi

Glutathione (μg/L) Glutathione ghi fghi ghi 1.0 ghi hi i hi i 0.5

0 Yeast 1 Yeast 2 Yeast 3 Yeast 4 Yeast 5 Yeast 6 Yeast 7 Yeast 8 Yeast 9 Yeast Yeast 10 Yeast 11 Yeast 12 Yeast 13 Yeast 14 Yeast 15 Yeast 16 Yeast 17 Yeast 18 Yeast 19 Yeast 20 Yeast

Yeast Strain

Figure 5. Reduced glutathione (GSH) concentrations at the end of alcoholic fermentation after adding 20 different commercial Saccharomyces cerevisiae strains Vertical bars denote 95% confidence intervals for the means. Letters indicate significant differences on a 5% (p<0.05) significance level (Kritzinger et al. 2013b, reproduced with the permission of the Australian Journal of Grape and Wine Research). potential of using enzymes by determining 4. Managing the Dimethyl of racking are generally situated under the the appropriate dose and the best timing to Sulphide Concentration in perception threshold. The goal of Dagan obtain the desired wine style. Bottles and Schneider is to identify and evaluate the winegrowing factors (e.g., hydric stress, The best moment to add an enzyme prepara- The work of Laurent Dagan (Nyséos) and maturity, production site, foliar spraying and tion high in glycosidases is following sulphit- Rémi Schneider (Institut Français de la Vigne varietal) that influence the potential DMS ing and after malolactic fermentation (MLF), et du Vin [IFV]) focused on dimethyl sul- (PDMS), of which the most important are when the winemaker is ready to evaluate the phide (DMS), associated with the percep- maturity and the varietal. However, dur- aroma impact of AF and MLF on the wine tion of herbaceous notes, truffle, cabbage, ing the study, the fermentation parameters profile, and to judge the remaining need to undergrowth and green olive in wine aromas, appeared to have a more determining impact enhance the complexity of the wine. where it also enhances the fruity character. on the concentration of PDMS at racking. Most of the DMS disappears with the CO 2 At the pre-fermentation stages of operations, during fermentation; the levels at the time such as macerating on skins and stabulation

250

225

200

175

150

125

Concentration (mg/L) Concentration 100

50 Control yeast

Mix Oenococcus oeni 2 Oenococcus oeni 1

Figure 6. Total ester concentration in wine after malolactic fermentation using 14 different yeast strains and three lactic acid bacteria starter cultures in co-inoculation and a control that was not inoculated for MLF, in a 2011 Merlot (Schöltz 2013) on lees, the solution for extracting PDMS, The wine made with oxidized juice and no four species of oenological bacteria gener- located mainly in the skin, remains to be SO2 presented significantly lower GSH con- ally present in wine, Oenococcus oeni is the explored. The fermentation conditions (e.g., centrations. Twenty commercial strains of bacteria best adapted to this hostile envi- yeast strains, nitrogen nutrition, fermenta- Saccharomyces cerevisiae were inoculated into ronment and the one most often utilized. tion temperature, fermentation adjuvants) synthetic solutions of grape juice, and GSH However, Lactobacillus plantarum is the one also have an impact on PDMS. The choice of levels were measured after AF. Significant most often utilized in fermentations destined yeast strain and the management of nitrogen differences were observed among the results for high pH wines and for co-inoculation. supplementation, notably, are the key param- obtained for the different strains (figure 5). L. plantarum produces different ester concen- eters to limit PDMS consumption by the Sauvignon juices containing various levels of trations. What’s more, this bacteria has the yeast during fermentation (figure 4). GSH were also analysed. During AF, signifi- capacity to release monoterpenes through Two strains of yeasts, L5 and L6, were inoc- cant trends appeared regarding the evolution its -glycosidase activity. The aroma profile ulated into MS120 synthetic must and a of GSH, according to the yeast strain utilized depends on the timing of inoculation. The Syrah must with and without the addition and the initial GSH concentration in the winemaker can get the most from all these of Fermaid E, a nitrogen nutrient designed juice. Sometimes the GSH concentration factors to adapt the wine style to consumer to prevent a possible deficiency in the must. increased over the initial level, which appears preferences. Adding this nutrient (5 g/hL) contributed to to indicate that the GSH is synthesized and 7. Volatile Compounds and the preserving a part of the PDMS. In the must secreted by the yeast. Perception of the Aroma with the L5 yeast, the percentage of residual Commercial preparations of GSH-enriched Attributes of Wine PDMS increased from 12% to 29%, which inactivated dry yeasts (GSH-IDY) were Dr. Ana Escudero, from the Universidad de shows that the addition of nitrogen has a pos- added at different stages of fermentation. The Zaragoza, Spain, reviewed current knowledge itive influence on the consumption of PDMS antioxidant potential of these preparations is and presented the latest findings on the by the yeast. With L6, the increase was not highly variable. The analyses showed that the aroma chemistry of wine. as marked, which confirms the specificity of addition can lead to higher GSH levels in the certain strains to assimilate the PDMS. wines, as long as the addition is made during Her research focuses on the key odour Indeed, the mastering of DMS in the wine the first third of fermentation. molecules perceived in wine. The aromas extracted through gas chromatography-mass can also occur through the management of The mechanism by which these preparations spectrometry (GC-MS) are the basis for a list PDMS during blending. As for aging, the influence the yeast metabolism and contrib- in which they are divided into two groups – correlations obtained allow us to predict the ute to increasing GSH levels, as well as their qualitative aromas and quantitative aromas. approximate percentage of releasable DMS, impact of the sensory profile of the wine, A series of sensory analyses followed with the but this model must be refined through better remains to be explored. knowledge of the influence of storage condi- purpose of reconstructing the wine aroma, tions on the percentage of DMS released. 6. The Impact of Wine Bacteria which gave rise to a new classification system. Already, new data on managing DMS levels and Different Malolactic According to this system, all the wines share in wine allow us to imagine integrated pro- Fermentation Scenarios on a common basic aroma structure that includes duction processes better adapted to the style the Aroma Profile ethanol and 27 aroma compounds, most of the final product. of which are by-products of fermentation. Professor Maret du Toit, from the University When combined, these compounds release 5. Glutathione – An Important of Stellenbosch, South Africa, presented the the aroma characteristic of wine and form an results of trials carried out in collaboration Antioxidant “aroma buffer” that has the capacity to buffer with Caroline Knoll and Doris Rauhut, from E. C. Kritzinger presented a study she con- several existing odorants, particularly those the Geisenheim Institute in Germany, for ducted in collaboration with Dr. Wessel du associated with fruity notes. The ability of the the purpose of evaluating the impact of wine Toit, C. Coetzee, and M. Gabrielli, from the different aromatic chemical compounds to bacteria and different MLF scenarios on wine University of Stellenbosch, South Africa, break this olfactory buffer and modulate the aromas. and with D. Fracassetti, from the University aroma profile of the wine, as well as the link of Milan, Italy, with the aim of better under- Changes to the aroma profile during MLF between the aroma note transmitted and the standing the evolution of glutathione (GSH) depend on different factors, such as the vari- aroma of the chemical compound from which during AF and verifying the effects of a wide etal and the aroma precursors, and on specific it results, are the basis for determining the range of oenological factors on the levels of parameters of the wine (notably the pH and contribution of the aroma compounds in the GSH in Sauvignon wine, which is subject ethanol level, which exerts a strong influ- aroma profile of the wine. Thus, a compound to oxidation. GSH has a protective effect of ence on the bacterial viability and activity). could be qualified as a genuine (high-impact) the wine aroma during aging. The researchers The choice of yeast strain for co-inoculation contributor, a major contributor, a secondary examined the effects of adding various com- also has a major impact on the final aroma (subtle) contributor, an aroma enhancer or an binations of O2 and SO2 to the must on the and style of the wine (figure 6). In addition, aroma depressor in the wine. GSH concentration in the must and in the wine bacteria synthesize and hydrolyze the Sauvignon wine. aromatic esters in various ways during MLF, according to the strain utilized. Among the

TO SUMMARIZE...

All new knowledge, every discovery related to wine aromas and the multiple factors that modulate their expression and participate in their balance make us realize the remarkable complexity of this field of research. The perspectives offered by current research are fascinating. The constant improving of our understanding of the effects of microorganisms and their derivatives on the varietal aromas of wine generates the ideas and the tools that will help winemakers modulate and define the style desired for their final product. References available upon request. You can obtain a copy of the proceedings of the XXIVes Entretiens Scientifiques Lallemand from your Lallemand representative.