Holiday Special
Fungus could take the fizz out of your celebratory champagne, French scientists have warned. They found that when champagne is made from grapes infested with Botrytis cinerea fungus, it is lifeless and less frothy when poured.
鈥淚n general, B. cinera infection was very detrimental to appearance during pouring,鈥� says Richard Marchal, who led the research at the Laboratory of Oenology, University of Reims.
Marchal collaborated with researchers working for the French champagne giant, M枚et & Chandon in Epernay, which is keen to tackle the problem.
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With the help of a robotic 鈥渨aiter鈥� programmed to pour the drink in a repeatable way, Marchal and his colleagues tested champagne made with three classic grape varieties 鈥� Chardonnay, Pinot noir and Pinot meunier.
The champagne was made from batches of grapes with B. cinera infection rates of 20 and 40 per cent. Although a 40 per cent rate is rare, infection levels can reach 15 to 20 per cent in a bad year.
Peak heights
Part of the appeal of champagne is the long delay before the bubbly froth 鈥渃ollar鈥� in the glass separates out as liquid. The researchers found that this 鈥渃ollar鈥� was badly affected by the fungus.
Compared with 鈥渦ninfected鈥� champagne, the collar collapsed into liquid six times faster from Pinot noir champagnes and 43 per cent faster from Chardonnay champagnes. And this was at just 20 per cent contamination.
At maximum contamination, the collar vanished two and a half times faster from Chardonnay, and eight times faster from Pinot noir. Collars survived best in Pinot meunier compared with 鈥渦ninfected鈥� controls.
Peak heights reached by the foam in the glass were badly affected too. 鈥淔oam heights are important in terms of product attractiveness for the consumer,鈥� says Marchal.
Acid test
To investigate this, Marchal and his colleagues measured the height of the foam in a glass at set times after pouring had begun.
They found that at 20 per cent contamination, Pinot noir heights were 83 per cent lower than for uninfected wines after 80 seconds of pouring. Pinot meunier heights were 89 per cent lower. At maximum contamination, foam heights after 80 seconds were 90 per cent lower in both Pinots. Chardonnays were affected, but to a much lesser extent.
Marchal and his colleagues have no immediate explanation for the effects. But they did find less tartaric acid and more potassium in the 鈥渋nfected鈥� wines. The team is now investigating whether this could impede foaming.
Aside from its affect on fizz, B. cinerea makes champagne smell mushroomy, mouldy and even rotten at high levels. But in the production of some wines, such as French sauternes, it is dubbed 鈥淣oble rot鈥� because it concentrates flavour by shrivelling ripe grapes.
Journal reference: Journal of the Science of Food and Agriculture (vol 81, p 1370)
