LISBON, PORTUGAL, LISBON, PORTUGAL, APRIL 18, 2013 APRIL 18, 2013 UNDERSTANDING VARIETAL E AROMAS DURING ALCOHOLIC AND MALOLACTIC FERMENTATIONS TION IN WIN A 20 T 20 CTIC FERMEN A L O L MA LISBON, PORTUGAL, APRIL 18, 2013 UNDERSTANDING VARIETAL AROMAS DURING ALCOHOLIC AND MALOLACTIC FERMENTATIONS PROCEEDINGS OF THE XXIVes ENTRETIENS SCIENTIFIQUES LALLEMAND FOREWORD t the XXIVes Entretiens Scientifiques Lallemand, can be responsible for various aromas, including truffle, researchers presented the most recent findings herbaceous notes, undergrowth, cabbage and fruity sen- Aregarding varietal aromas, and the impact of al- sations. He presented the results of the research on pre- coholic and malolactic fermentations on their release into cursors for DMS and how to modulate the concentration wine. in wine. For this occasion, the Lallemand – Institute of Masters of Engela Kritzinger presented the results of her Master’s the- Wine research bursary was awarded to Clare Tooley of sis done at the University of Stellenbosch with Dr. Wessel France, a first-year student in the Master of Wine program, du Toit on the role of glutathione in wine. Recent research for her essay, “In the context of the current market, how has come to the fore explaining the role different levels of do viticultural practices influence the varietal aromas?” In oxygen and sulphur dioxide, yeast strains and commercial addition, the winners of the ML Wine competition (Ma- glutathione-enriched inactivated dry yeast preparations drid, 2013) received their awards from Dr. Sibylle Krieger, (GSH-IDYs) play on GSH concentrations in wine. GSH- the director of the Lallemand Malolactic Fermentation IDY additions to juice have been shown to increase the School. GSH levels of wine when used correctly. The meeting opened with Eduardo Agosin, one of the Wine bacteria also play an important role with varietal most respected researchers in wine aromas. Professor aromas. Dr. Maret du Toit, also from the University of Stel- Agosin, from the Pontificia Universidad Católica de Chile, lenbosch, has shown that different malolactic fermenta- discussed potential varietal aromas. This potential arises tion (MLF) inoculation strategies can be used to change from glycosidic and cysteinylated conjugates, which can the wine style – a major trend for the fresh and fruity wine contribute significant aromas to wine once freed from the styles. Her work demonstrated that the wine matrix, pH bound fraction, either by enzymatic or acid hydrolysis and alcohol concentration affect MLF and the final vol- during fermentation and aging, respectively. atile aroma profile. The changes in volatile aroma com- position can also be driven by using different lactic acid Coming all the way from the University of Auckland in bacteria strains. New Zealand, and famous for his research on Sauvignon Blanc, Dr. Mat Goddard gave an impressive talk on re- To conclude the XXIVes Entretiens Scientifiques Lallemand, search to better understand the microbial ecology of vines Dr. Ana Escudero from the Universidad de Zaragoza in and wines, and to harness beneficial strains more reliably. Spain presented a review of her group’s knowledge and He presented recent findings that show New Zealand har- understanding of the roles played by different aroma bours a distinct population of yeasts. chemicals in the positive aroma attributes of wine, and also presented a systematic approach to classifying the Touriga Nacional (TN) is a varietal typical of Portugal, different aroma chemicals of wine. characterized by a bergamot-like, fruity-citric-floral aro- ma and is attributed to terpenol, linalool and its acetate. The more we know about wine aroma, and the more we Dr. Frank Rogerson of Symington Family Estates in Por- realize that such a complex matrix, with so many factors tugal presented on the possible modulation of key odor- influencing the equilibrium of this environment, still has ants responsible for the bergamot aroma in TN, while in- much to reveal. Current research offers a fascinating per- vestigating the effect of a commercial pectolytic enzyme spective, and understanding the impact of wine microor- preparation rich in beta-glucosidase activity. ganisms and their derivatives on wine varietal aromas pro- vides useful tools to help winemakers shape and master The research done by the NYSEOS group and presented the final wine style. by Dr. Laurent Dagan is very interesting. Dimethyl sul- phide (DMS) is a versatile aroma compound that can have significant effects on the sensory properties of wine. De- pending on its concentration and the type of wine, DMS – 3 – CONTENTS UNDERSTANDING VARIETAL AROMAS DURING ALCOHOLIC AND MALOLACTIC FERMENTATIONS THE AROMATIC POTENTIAL GLUTATHIONE: RECENT DEVELOPMENTS OF WARM CLIMATE WINES ......................................7 IN OUR KNOWLEDGE OF THIS IMPORTANT ANTIOXI- Eduardo AGOSIN DANT .......................................................................49 Engela C. KRITZINGER, Carien COETZEE, Daniela FRACASSETTI, Mario GABRIELLI, MERGING ECOLOGY Wessel J. DU TOIT AND WINE MICROBIOLOGY ..................................17 Matthew R. GODDARD CHASING VARIETAL AROMAS: THE IMPACT OF DIFFERENT ENZYME-CATALYZED MODULATION LACTIC ACID BACTERIA AND OF THE TYPICITY OF TOURIGA MALOLACTIC FERMENTATION SCENARIOS ...........61 NACIONAL AROMA AND FLAVOUR ......................23 Maret DU TOIT, Elda LERM, Hélène NIEUWOUDT, Frank S. ROGERSON and Charles SYMINGTON Sulette MALHERBE, Marené SCHÖLTZ, Caroline KNOLL, and Doris RAUHUT CONTROLLING DIMETHYL SULPHIDE LEVELS IN BOTTLED WINES ................................................39 CHEMICAL SYSTEMS BEHIND Laurent DAGAN and Rémi SCHNEIDER WINE AROMA PERCEPTION ...................................69 Ana ESCUDERO and Vicente FERREIRA – 5 – THE AROMATIC POTENTIAL OF WARM CLIMATE WINES Eduardo AGOSIN1, 2 1Department of Chemical and Bioprocess Engineering, School of Engineering, Pontificia Universidad Católica de Chile, Casilla 306 Correo 22, Santiago, Chile 2Centro de Aromas y Sabores, DICTUC, Av. Vicuña Mackenna 4860, Santiago, Chile Abstract a grape varietal may be grown in a remote geographic zone and is turned into wine through different techniques, the As far as consumers are concerned, the aroma and flavour resulting wine will possess certain qualities inherent to the of wine are among the main characteristics that determine its quality and value. The aroma of a wine is a unique typicity of this varietal. Consequently, the identification and mixture of volatile compounds originating with the grapes quantification of the aroma compounds present in the grape (varietal aromas), and secondary products formed during are vital, as they define, in large part, the quality of the final the fermentation of the wine (fermentative aromas) and product (Ribéreau-Gayon et al. 1998). during aging (post-fermentative aromas). The composition Wines are made up of about 800 volatile compounds, of the grape – which is unique to the variety and the ter- present in concentrations that range from a few nano- roir – makes a significant contribution to each wine, dis- grams to hundreds of micrograms per litre. They make tinguishing one wine from another. up the free fraction of the aroma of wine, and include The potential varietal aroma is also important. Such potential the odour compounds. There are other groups of com- arises from glycosidic and cysteinylated conjugates, which pounds as well, from the grape varietal, called precursors can contribute significant aromas to the product once they (the bound fraction in the final aroma), which constitute are freed from the bound fraction, either by enzymatic or the aromatic potential of the wine. This is formed by non- acid hydrolysis during fermentation and aging, respectively. volatile compounds, which, consequently, can never be perceived by the nose. Nevertheless, they are likely to In this paper, I will review our research of recent years liberate varietal aromas after hydrolysis during vinifica- on the characterization of the aromatic potential of red (Carménère and Malbec) and white (Sauvignon Blanc and tion or aging, depending on the nature of the precursor Muscat) wine grape varietals grown in Chile and Argen- (Bayonove et al. 2000). This fraction of the wine aroma tina, and the evolution of this potential during fermenta- is the focus of this study, in which we present the results tion and aging. An attempt to quantify the recovery yield obtained by our team over the past few years. of these potential aromas and their sensory impact on the final wine will also be presented. 2. Glycosylated Aroma Precursors in Muscat Varietals 1. Introduction Terpineols are the basis for the typicity of Muscat grapes The aromas of a wine are linked to the different stages of its (Baumes et al. 1994). In the case of varietal aromas, ter- elaboration and to the savoir-faire of the oenologist, but fun- pineols contribute significantly to the typicity of wines damentally the bouquet of a wine is a reflection of the poten- through their aroma characteristics and thanks to a rela- tial of the initial grape, the varietal and the terroir. Although tively low detection threshold. – 7 – UNDERSTANDING VARIETAL AROMAS DURING ALCOHOLIC AND MALOLACTIC FERMENTATIONS The compounds responsible for fruity/floral aromas spe- The study of the aromatic potential of more than 50 cific to these varietals are principally linalool, nerol, ge- samples / varietals of Muscat of Alexandria and Muscat raniol and, to a lesser degree, citronellol, -terpineol, Rosé