Winetech Technical Yearbook 2022

SEPTEMBER

Effect of cork or crown cap closures on MCC bubbles A COLLABORATIVE STUDY WAS UNDERTAKEN BETWEEN THE CAP CLASSIQUE PRODUCERS’ ASSOCIATION AND THE ARC TO INVESTIGATE DIFFERENCES BETWEEN CORK-CLOSED AND CROWN CAPPED WINES.

LISA LOTTERING

BY NEIL JOLLY

INTRODUCTION Sparkling wine is characterised by CO 2 content and the bubbles are the ‘sparkle’ that distinguishes sparkling wines from still wines. This is the characteristic that consumers generally find appealing. The bubbles also add to the typical mouthfeel imparted by the release of dissolved CO 2 in the mouth. During production, bottle-fermented sparkling wine undergoes a second alcoholic fermentation in the same bottle it is sold in. It is a standard practice to use a crown cap to close this bottle. After the legislated period of maturation on the yeast lees, the wine is clarified and the crown cap is removed. The bottle is then resealed with the customary two-disk cork kept in place by a wire hood (muselet). Before the development of crown caps in the 1960s, 1 a cork, secured with a metal staple, was used during the second fermentation. Some international producers never changed from this protocol and still use cork for the second fermentation of their premiumwines, despite the risk of cork taint. For example, the Champagne Dom Perignon Plénitude can be in contact with a cork while on the yeast lees for up to 15 years before being released. 2 One of the reasons for the use of a cork is a desired stylistic effect imparted to the wine. Méthode Cap Classique (MCC) producers have noted that the use of a cork closure during the second fermentation delivers a desired smaller bubble and lengthens the time that the bubbles remain in the glass. Part of this project investigated the CO 2 kinetics (the behaviour of bubbles or CO 2 ) after a glass of MCC wine had been poured. This article is a summary of information presented in a publication in the South African Journal of Enology and Viticulture , Volume 42. 3 MATERIALS AND METHODS Six treatment pairs of commercially prepared bottle-fermented sparkling wines, covering the 2012, 2013, 2014, 2015 and 2018 vintages, were obtained for analyses from three MCC producers. These wines had been in contact with the yeast lees between four

and 72 months at time of analyses. For each sparkling wine pair, the only differences between the wines were a cork or crown cap closure during fermentation and maturation on lees. Before analyses, the wines were disgorged by the respective cellars and all were reclosed with a crown cap. A method was adapted to measure the amount of CO 2 lost from an ISO wine tasting glass (CO 2 mass loss), and the change in the number of visible bubbles in a flute glass over 20 minutes (bubble count). The counting method did not distinguish between small and large bubble sizes and individual bottles served as replicates. RESULTS AND DISCUSSIONS In this investigation, 20 minutes was considered a reasonable time elapse from pouring a glass of MCC wine to consumption in a social setting. However, many consumers would probably finish their glass in a shorter time. The quantity of CO 2 that could potentially be lost from a glass depends on the quantity initially present in the bottle i.e., the bottle pressure. Wines at high pressures lose CO 2 faster than those at low pressures to attain a gas equilibrium between the wine and the headspace of the glass. Additionally, the turbulence caused during pouring, results in a notable further loss of dissolved CO 2 , especially for the first glass poured. 4 Generally, the crown-capped wines had higher pressures compared to the cork wines. It was therefore expected that the crown-capped wines would lose more CO 2 than the cork-closed wines. This was true for four of the six wines, but only statistically significant for one of the four wine pairs (figure 1). The remaining two wines, both from the same producer, showed the converse and more CO 2 was lost from the cork wines which was not in agreement with the initial pressure readings. These discrepancies may be due to the pressure readings and mass loss kinetics measurements been taken on different bottles. However, the average trend across all treatments showed that the cork wines retained their CO 2 content marginally better than the crown-capped wines after pouring.

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WINETECH TECHNICAL YEARBOOK 2022