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58 P R A C T I C A L W I N E R Y & V I N E YA R D October 2015 W I N E M A K I N G T E C H N I C A L R E S O U R C E F O R G R O W E R S & W I N E R I E S Don Neel, Editor practicalwinerylibrary.com Access Practical Winery & Vineyard article archives online. A lthough few scientific studies have been carried out regard- ing "gushing" during the dis- gorging of sparkling wines, many factors have been implicated in the phenomenon. These factors include phenolic compounds (particularly tan- nin, such as excess addition of tannin in the tirage), bottle shaking, ambient temperature during disgorging, insuffi- cient bottle cleaning, cork dust, ultravio- let (UV) lighting in the disgorging area (especially natural sunlight from open doors or through windows onto bottles waiting to be disgorged), incomplete rid- dling prior to neck freezing, lack of tar- taric acid stabilization, calcium crystals and protein instability. 6,10,16,17 Wine loss from gushing causes financial loss in addition to a decline in bottling-line speed and efficiency. 6 Studies that focused on beer gushing found that some proteins (hydrophobins and lipid transfer proteins [LTPs]) can be responsible, even at very low levels (ppb scale), for beer gushing. 18,19,20 These proteins are excreted from some fungi (Fusarium and other barley contaminants) and remain sta- ble during the beer-production process. It is likely that some grape contaminants could exhibit the same behavior in sparkling wine as previously described in beer. 6 Inexplicable gushing has been reported in sparkling wine bottles that lack tartrate crystals, possess turbidity issues, undergo malolactic fermentation (MLF) in the bot- tle or experience riddling problems. It is possible that proteins are involved. 7,8 If proteins do contribute to gushing in spar- kling wine, then the protein type and con- centration required needs to be identified, although several studies in recent years have investigated the positive relationship between protein and foaming ability. 6 It is well known that opening a sparkling wine bottle immediately after shaking cre- ates gushing. 23 Calcium tartrate (CaT) crys- tals are also responsible for gushing and are more common in sparkling wines than still wines. 21,25 CaT precipitation is highly pH- dependent, and any activity that increases the pH (malolactic fermentation and blend- ing) increases the possibility of CaT pre- cipitation. 25 Causes of gushing that have been suggested by sparkling winemak- ers and researchers in published stud- ies can broadly be divided into three categories: 1) bottle handling and disgorg- ing environment, 2) wine composition and 3) packaging materials (see Figure 1). 6,7,8,10,16,21 The aim of this study was to investigate the cause of gushing in a Riesling spar- kling wine, which had a history of gushing when the crown cap was removed at dis- gorging, by considering the environmental conditions of temperature and light expo- sure prior to disgorging. This small-scale trial was conducted in a commercial winery using a temperature range of 10° to 16° C with LED and UV lights for 90 minutes at each ambient temperature prior to disgorging. The wine analyses car- ried out included compounds indicated in Figure 1 that have been associated with gushing to determine why gushing occurred in some bottles but not others, under each light/temperature environment. Materials and methods The difficulty with investigating gushing of alcoholic sparkling wines is in forcing Belinda Kemp, Ben Wiles and Debbie Inglis, Cool Climate Oenology & Viticulture Institute, Brock University, Ontario, Canada BY Gushing of Sparkling Wine at Disgorging • Light (UV) • Ambient temperature • Seasonal timing of disgorging • Rough handling before disgorging • Angle of the bottle • Neck freezing too fast • Rapid movement of wine from cold room to warm room • Grape variety • Vintage variation • Protein instability • Wine temperature and dosage temperature • High bottle pressure • Tartrate crystals • Calcium crystals • Inconsistent mixing during tirage • Undissolved sugar in the dosage after addition • Yeast (from inadequate riddling/neck freezing) • High phenolic concentration • Turbidity • Malolactic fermentation in bottle • Cork dust • Glass imperfections in the bottle • Dust in the bottle Bottle handling and disgorging environment Wine composition Packaging materials Figure 1. Factors associated with gushing during the disgorging of méthode champenoise sparkling wines. Produced using information from Robillard and Liger-Belair 2007, Liger-Belair and Robillard 2008, Liger-Belair et al. 2013a + 2013b, Vignes-Adler 2013, Kemp et al. 2015. REASONS AND REMEDIES