Issue link: http://winesandvines.uberflip.com/i/929459
February 2018 WINES&VINES 63 PRACTICAL WINERY & VINEYARD GRAPEGROWING jury to counteract bacteria and fungi. 17 Regarding the chemical structure of trans- resveratrol, certain similarities to the smoky volatiles can be observed immediately. Similar to guaiacol, syringol and o-cresol, trans-res- veratrol possesses a basic phenolic structure and functional hydroxyl groups that enable the linkage of a sugar moiety. Therefore, the scientists at the Technical University of Mu- nich argue that the grapevine enzyme cannot distinguish between its natural substrate trans-resveratrol and the foreign smoky mol- ecules. 3 It is processing both. Problems for the winegrower One might think that this intrinsic grapevine activity is an advantage, as the smoky volatiles are rendered non-smoky and masked by the binding to a sugar molecule. However, during winemaking, the bound smoke compounds are cleaved (hydrolyzed) from sugar molecules, thus allowing the smoky volatile phenol aro- KEY POINTS Smoke from wood fire contains volatile phenols with an ashy aroma that enters the grapes mainly through skins and the waxy cuticle. Native grapevine enzymes called glycosyl- transferases bind sugar molecules to the volatile phenols, rendering them odorless and hidden within the juice. During fermentation of the grape juice and upon consumption of the wine, the sugar molecules are cleaved off, leading to a progressive release of the smoke com- pounds and creating an unpalatable taste. O OH CH 3 sugar transfer by glycosyltransferase enzyme O SUGAR CH 3 fermentation O OH CH 3 in proximity of leads to forest fire vineyards smoke taint The above sequence is responsible for the uptake and release of smoke taint in grapevines. Sugars are added by a process called glycosylation and are cleaved off again during fermentation. UPTAKE AND RELEASE OF SMOKE TAINT IN GRAPEVINES 3435 Ocean Park Blvd, #107-511 ~ 10 rue François Appert – BP 90095 21703 Nuits Saint Georges Cedex France Growing grapes in northern tier states requires new solutions to new challenges. The CCC brings over 40 experts from Viticulture, Enology and Business to share insights and experience as this new industry continues to expand. cold climate conference bloomington doubletree hotel 2018 March 15 17 MINNESOTA GRAPE GROWERS ASSOCIATION invites you to attend the 13th Annual Grape and Wine Conference in Bloomington, MN Register at MNgrapes.org Come for the Sessions Stay for the Party!