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November 2015 WINES&VINES 123 WINE EAST WINEMAKING Harvesting methods New Zealand Sauvignon Blanc is known to contain some of the highest concentrations of volatile thiols of any wine in the world, according to Frank Benkwitz. Most of the Sauvignon Blanc in Marlborough, N.Z., is harvested with machines out of necessity. This is fortuitous, as it has been demonstrated by several research- ers that machine harvesting of fruit results in higher concentra- tions of volatile thiols in wines compared to wines made from hand-harvested fruit. Thomas Allen hypothesized in 2011 that an increase in enzymatic activity in "damaged" machine-harvested fruit may play a role in the forma- tion of thiol precursors, which might explain the increase in vola- tile thiols in the resulting wine. The time of day at which the fruit is harvested also may play a role in the concentration of thiols in the resulting wine. Oxidation will occur faster in warmer juice than cooler juice. This oxidation can then lead to loss of aromatic potential by the volatile thiols, as it can lead to formation of qui- nones, which will oxidize the vola- tile thiols after fermentation, Allen said. Therefore, harvest should be conducted in the cooler periods of the day in order to mini- mize oxidation. Cold soak In other growing regions, such as the eastern United States, ma- chine harvesting is not commonly practiced. However, winemakers can try to mimic the effect of ma- chine harvesting through the use of cold maceration. The only stud- ies I know to have evaluated the impact of a traditional cold soak on thiol concentrations have sim- ply measured the amino acid- conjugated thiols in the must. The conjugated thiols tend to increase in must that has had a cold soak. However, because the conjugated thiols in juice represent less than 10% of the final volatile thiol con- centration in wine, the results from these studies can't be ex- trapolated to final wine. For a study using a novel cryo- genic maceration technique, Sau- vignon Blanc was harvested, crushed and underwent a cold soak at -4° F (-20° C) using dry ice. Upon reaching -4° F, the must was allowed to warm over a 24-hour period to ambient temperature before it was pressed and vinified. In this study, concentrations of volatile thiols in wines made from hand-picked/cryogenically macer- ated fruit were greater than those measured in wines made from machine-harvested fruit. Through sensory analysis, the wines made from hand-harvested fruit were found to be less aromatic than the wines of machine-harvested fruit. However, no discernible sensorial difference was seen between the w i n e s m a d e f r o m m a c h i n e - harvested fruit and cold-soaked musts, according to university researcher Kenneth J. Olejar. Fur- ther research is needed to deter- mine the efficacy of cold soaks as a means to increase the aromas coming from thiols. Regardless of whether or not volatile thiols increase with skin contact, they may increase reduced glutathione (GSH) concentrations in the resulting wine. GSH is a naturally occurring antioxidant in Wine Packaging by Packaging Designed & Manufactured by a Wine Maker, for a Wine Maker 4138 Vineyard Road Stewartstown, PA 17363 Tel: 800-292-3370 Fax: 717-993-9460 Phone: 717-993-2431 Naylor Wine Cellars is a lifetime member of Wine America, Pennsylvania Wine Assoc, Ohio Wine Producers and NY Wine & Grape Foundation WPN is a premier supplier to over 2,000 wineries and wine & spirits shops. Our auto bottom carriers & shippers are the perfect sturdy solution for your retail & online sales! www.NaylorPackaging.com Features & Benefits - Extra sturdy construction for the most protection - Quick & easy to pack & set up - Folds to conform to many different bottles - Trademarked design - Bio-degradable - Quick delivery from our stock - Lies flat for easy storage - Takes up half the space of comparative packages - Tested & approved by UPS and Federal Express as a preferred method of shipping bottles - Custom imprinting and packaging is available to display your logo, enhancing your brand image OLFACTORY DESCRIPTORS OF THIOLS Volatile thiol Aroma description 4-mercapto-4-methylpentan-2-one (4MMP) Box tree, broom, black currant and passion fruit 3-mercapto-hexan-1-ol (3MH) Passion fruit, gooseberry, grapefruit and guava 3-mercapto-hexylacetate (3MHN) Passion fruit, box tree, grapefruit, guava and gooseberry Source: Coetzee & du Toit, 2012