THE CHEMISTRY OF WINE H2O, et al. Terroir An Integrated Wine Science Publication MOVE OVER, AVOCADO TOAST millennials and the wine market CHEATING THE SYSTEM aged wine taste, without the wait TEMPERATURE AND WINE the perfect balance SULPHITE SURPRISE preservation, at what cost? THE FUTURE IS NOW iSci winemaking tech RED WINE HYPE fact-checking the claims BRACE FOR IMPACT wine in a changing climate IN IT FOR THE LONG HAUL sustainable viticulture FROM THE GROUND UP soil and wine taste ISCI Vintage 2017 iSci VINTAGE 2017 Terroir An Integrated Wine Science Publication Established 2013 Terroir is published by Integrated Science at McMaster University as part of the ISCI 3A12 Wine Science Project, with management by Dr. Carolyn Eyles & Russ Ellis For further information about the project, please contact us at [email protected] WINE SCIENCE THE CHEMISTRY IN YOUR GLASS OF WINE: 2 Craughwell, M., Doan, A., Graham, K., Lefebvre, Working in small groups, students in ISCI 3A12 M. examine the science behind wine making, from the art of viticulture to its eventual consumption by the WHAT ARE MILLENNIALS WINE-ING ABOUT public. Students perform literature-based reviews and 13 NOW?: Chou,Table S., Coles, of V.,Contents Norman, B., Smith, original research in order to understand the wine J. industry and its complexity; including the environmentalHOW CAN SOMETHING requirements THAT and TASTES consequences SO GOOD BE of SO TANNINS AND BARRELS AND ULTRASOUND, OH winemaking, theSCIENTIFICALLY short- and loINTERESTING?ng-term health effects of 23 MY!: Houpt, N., Martin, S., Wynn, G., Yeung, J. drinking wine, and what factors contribute to the quality, aroma, and taste of wine. This research was formatted to resemble a publicly accessible scientific THE IMPACT OF TEMPERATURE VARIABILITY 33 article, and compiled to create each Vintage of Terroir. WITH MITIGATION STRATEGIES FOR NIAGARA GRAPES: Ahluwalia, M., Bolger, R., Johnstone, G., Yu, B., Zhang, N. This Publication is written by members of the ISCI 3A12 class of 2017. 44 SULPHITES OR SULPH-YIKES?: Barker, B., Garnett, J., Sitarz, U., Stewart, J., Takahashi, M. MODERN TECHNOLOGY IN THE WINEMAKING 55 PROCESS: Coppens, J., Fraschetti, A., Koniar, H., Loukiantchenko, E., Vitali, E. RED WINE: IS IT AS HEALTHY AS COSMO 66 CLAIMS?: Liu, A., Macklai, S., Maclean, C., Sreerangan, P., Yachouh, J. THE FUTURE OF VITICULTURE IN THE NIAGARA 78 APPELLATIONS: Conant, A., Greenblat, L., Kawamoto, C., Saunders, J., Tweedle, A. CREATING SUSTAINABLE VINEYARDS IN Cover Image: Schwappender Wein. Wikimedia 88 NIAGARA: Gillis-Adelman, M., Kim, N., Pavic, Commons. Stefan Krause. 2009 S., Swing, M., Tam, A. Table of Contents Image: Port Wine. Wikimedia Commons. Jon Sullivan. 2003. DRINK WINE, GET DIRTY: AlShenaiber, L., 103 Balint, L., Bider, P., Daniel, T., Sharpe, I. EDITORS: Russ Ellis, David Bowman TERROIR | 1 The Chemistry in Your Glass of Wine Behind the complex flavours, lies a full body of science Meghan Craughwell, Alexi Doan, Katie Graham, and Michele Lefebvre Grapefruit, spicy, earthy, melon, blackcurrant, lavender, vanilla, grass. It seems as though wine can taste like just about anything. The taste can even be as absurd as leather, petrol, or wet dog. How do these complex flavours emanate from a single fruit? It is all in the science of winemaking. Many biochemical reactions, beginning with the ripening of the grape, continuing throughout fermentation, and ending in your glass of wine, are responsible for these diverse flavours. The underlying science can explain the variation in wine flavour across regions and open the door to innovation. Winemakers in the Niagara Region are creating a niche for Canada by capitalizing on its unique climate and their willingness to try something new. 2 TERROIR | Flavour is a result of the combination of two stimulated by non-volatile compounds and senses: taste and smell (Bakker and Clarke, distinguishes between a sweet or bitter wine 2012). It helps shape our likes and dislikes, (Polášková, Herszage and Ebeler, 2008; and is extremely important in the food and Bakker and Clarke, 2012). wine industry. Unlike many other beverages, Although taste plays an important role in wine has the ability to take on countless wine flavour, aroma has the most significant flavours. When describing wine flavour, we effect on flavour perception (Polášková, usually refer to the smell as the aroma. Herszage and Ebeler, 2008). The aroma Aroma is the pleasant response of the sense skeleton of wine consists of the major of smell, specifically the olfactory (smell) groups of volatile compounds: alcohols, system, when stimulated by volatile aromatic esters, acids, aldehydes, and acetals (Romano compounds (Salo, 1970). There are a wide et al., 2003). These compounds are perceived variety of wine aromas including orange through both the smelling and tasting of blossom, passion fruit, and truffle, as seen in wine due to a portion of compounds that Figure 1. In contrast, the taste of wine is travel retro-nasally through the back of the sensed by the gustatory (taste) system when mouth to the olfactory organ (Bakker and FIGURE 1: AROMA WHEEL. This presents the many different aromas of wine, with the simpler terms in the centre and complex descriptors on the outer tier of the wheel (Aromaster, 2012). TERROIR | 3 Clarke, 2012). This explains why the increases (Robinson and Harding, 2015). perceived flavour can often change The amount of acid and sugar in the final drastically from the perceived aroma. stages of ripening have a large impact on the Additionally, the perceived aroma is final flavour of the wine, as well as the determined by the sensory threshold of the flavour compounds and precursors compound, which is defined as the minimal synthesized in this stage (Conde et al., 2007). level at which a substance can be detected by Flavour compounds produced during a human (Salo, 1970). development and ripening vary in Wine flavours can originate from the grape, composition and relative ratios depending others present themselves after on grape variety, which explains the fermentation, and a portion arise later signature flavours of varietals (Polášková, throughout the aging process (Romano et al., Herszage and Ebeler, 2008). The large 2003). In brief, these flavours are a complex diversity across varietals and presence of cocktail of varietal, fermentative and post- flavour compounds in the grape are thought fermentative flavours. to fulfill an evolutionary role. This includes attracting insects to assist in pollination, defending the berry flesh from insects and THE HUMBLE GRAPE microbes during development, attracting The grape plays a crucial role in determining birds that eat and disperse the seeds, and wine flavour. Each grape is essentially a inhibiting germination of competitive plant reservoir of sugars, acids, phenols, flavour species (Robinson and Harding, 2015). compounds, and flavour precursors that Growing conditions, including soil influence wine character (Polášková, composition, sunlight, and climate, strongly Herszage and Ebeler, 2008). The collection influence the chemical composition of the of compounds in the grape is a product of grape and thus play an important role in biochemical and physiological changes that shaping the final flavour of wine (Conde et occur during two stages of berry growth: al., 2007). The effect that climate can have on development and maturation (Conde et al., wine character is especially noticeable in 2007). regions, such as Niagara, with cooler grape Several solutes accumulate in the berry growing conditions. during the initial development or growth period. The primary compounds are malic acid and tartaric acid, which determine the COOL CLIMATE WINES acidity of the berry and thus the acidity of the The climate in which grapes are grown can wine (Conde et al., 2007). Other solutes that have a noticeable impact on flavour develop include minerals, amino acids, compounds and precursors. Many vineyards micronutrients and aromatic compounds. are located in regions with warm climates to The second phase of growth involves the allow for maximal growing seasons, but maturation or ripening of the grape, when some vineyards are located in cool climate the most dramatic changes in berry regions, such as the Niagara Peninsula in composition occur. As grapes mature, acid Ontario (Shaw, 2005). This popular wine content decreases and sugar content region is considered to have a semi- 4 | VINTAGE 2017 continental climate, moderated by Lakes Erie nutritional stress, leading them to produce and Ontario, creating an area with a favourable climate for grapes. Even though Niagara vineyards grow approximately 50 different varietals, common flavour characteristics unite many of the wines, which can be attributed to the cool climate (Robinson and Harding, 2015). Cool climate wines are usually described as delicate and refined with a higher acidity that gives freshness (Tarko et al., 2014). Since the FIGURE 2: ALCOHOLIC FERMENTATION. Pinot growing season is shorter, the chemical noir grapes undergoing primary fermentation, as composition of the grapes differs slightly indicated through the carbon dioxide foam atop the from those grown in warm climates. Often grapes (Smith, 2010). these grapes ripen later and sometimes different compounds, such as succinic acid incompletely, resulting in a lower sugar (Baroň and Fiala, 2012). Although the direct content, and thus a slightly lower alcohol cause of minerality is not yet known, it content. Additionally, the fruit has a higher provides