Sparkling wine gushing: not a cause for celebration Many consumers have had the experience of opening a bottle of sparkling wine and having the contents spontaneously gush from the bottle. In this column, AWRI Oenologist Ben Cordingley addresses questions asked by sparkling winemakers about why unintentional gushing occurs, the main causes, and what steps can be taken to prevent its occurrence. What is gushing? The chemical composition of a wine Inadequate cold stabilisation influences the bubble formation and the A bottle of sparkling wine can release five Any solid material in a sparkling wine positive foaming properties of sparkling litres of gaseous carbon dioxide (CO₂) wines. Sparkling wines with desirable bottle can act as a nucleation site for after opening, ideally in a controlled bubble formation, where its rough surface manner, giving a sparkling wine its foam behaviour often contain surface- can store trapped gas and encourage distinctive effervescent character. active grape- and yeast-derived proteins. Gushing is the rapid and uncontrolled These ‘foam-active’ proteins increase the rapid degassing and gushing. The most increase of gas volume that results in surface tension of the gas/liquid interface common solid the AWRI helpdesk has the expulsion of foam from a bottle of a microbubble, which gives stability to observed in cases of gushing is potassium of sparkling wine. Producers can the bubble and leads to a fine persistent hydrogen tartrate (KHT) crystals that experience substantial economic losses foam character. arise from inadequate cold stabilisation. if affected bottles need to be replaced When checking the stability of a sparkling for consumers. Gushing wines can also Which factors influence pose a safety risk, as consumers can be gushing and what steps can be base wine that will undergo secondary injured by fast-moving corks. Gushing taken to prevent it occurring? bottle fermentation, the base wine can can occur sporadically or across an be fortified with an addition of 1-1.5% Excessive carbon dioxide entire batch, which may require the wine ethanol to model the increase in alcohol to be reworked. Australian sparkling wine must contain produced from secondary fermentation, a minimum of 5 g/L of dissolved CO₂ as this alcohol increase will reduce the Positive bubble formation in that is surcharged into the wine from solubility of KHT and increase the risk sparkling wine either direct carbonation or secondary of instability. Crystallisation inhibitors The release of gas microbubbles fermentation in bottle or tank. Wines are available as sparkling wine specific gives rise to the effervescence of a with levels of carbon dioxide greater sparkling wine, and the nature of the than 12 g/L are more likely to gush, formulations that may provide additional microbubbles affects quality parameters highlighting the importance of correct protection against cold instability. such as the appearance, mouth-feel and calculation and addition of tirage liqueur More information on these additives is foam behaviour (Cilindre et al. 2010). in traditional method sparkling wines. available from suppliers.
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42 Grapegrower & Winemaker www.winetitles.com.au November 2020 – Issue 682 Precipitated pigment, other solids, forming gas bubbles upon opening much For further information about sparkling or poor-quality glass more rapidly than CO₂. Nitrogen gas can winemaking or other technical also remain undissolved in wine as small winemaking or viticulture questions, Sparkling red wines represent a gas bubbles that function as nucleation contact the AWRI helpdesk on significant number of gushing cases sites for the explosive evolution of CO₂ (08) 8313 6600 or [email protected]. investigated by the AWRI, often due bubbles (Loitsch 2000). Headspaces of to changes in stability resulting from secondary fermentation tanks should References precipitation of pigment and tannin thus be flushed with CO₂ before sealing complexes. Other gushing inducers Cilindre C., Liger-Belair G., Villaume to remove oxygen and nitrogen. Base include calcium tartrate crystals, S., Jeandet P., Marchal R. 2010. Foaming wines should not be sparged with properties of various champagne wines diatomaceous earth, cork dust and metal nitrogen and aeration should be kept to depending on several parameters: Grape hazes. Poor-quality glass with a rough a minimum. variety, aging, protein and CO2 content. inner bottle wall can also be a source of Anal. Chim. Acta. 660(1-2): 164-170. greater numbers of nucleation sites and Botrytis an inducer of gushing. Kupfer V.M., Vogt E.I., Ziegler T., Vogel R.F., Fungal diseases can decrease proteins Niessen L. 2017. Comparative protein profile Residual yeast responsible for positive bubble formation analysis of wines made from Botrytis cinerea and foam stability by producing protein- Any residual yeast lees left in a sparkling infected and healthy grapes reveals a novel degrading enzymes (proteases). A recent wine will also increase the likelihood biomarker for gushing in sparkling wine. study by Kupfer et al. (2017) demonstrated Food Res. Int. 99(Pt 1): 501-509. of gushing. This might occur in that wine made from Botrytis-affected pétillant naturel (pét-nat) style wines Liger-Belair G., Polidori G., Jeandet P. 2008. or if riddling has been ineffective fruit had low protein diversity and Recent advances in the science of champagne before the disgorgement of traditional lower total protein levels, but contained bubbles. Chem. Soc. Rev. 37(11): 2490-2511. higher levels of hydrophobins, which method wines. Loitsch, S. 2000. Untersuchungen zu are proteins that induce gushing. The Nitrogen and oxygen gases Schaumphänomenen bei alkoholischen und study proposed that gushing wines often alkoholfreien Getränken. Berlin: Technische Dissolved oxygen or nitrogen can induce lack balance between hydrophobins that Universität Berlin: 46 p. Available from: gushing due to the low solubility of these induce gushing and foam-active proteins https://www.grin.com/document/98681 gases in wine, with the nitrogen or oxygen that protect against gushing. (German)
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