en passant par le laboratoire de chimie...
voici un petit article (désolé en anglais) sur les pratiques de plus en plus répandues dans le petit monde du vin
quand on connaît mes difficultés avec la chaptalisation, l'acidification et les divers pesticides ou engrais, on déduira vite mes conclusions sur ces pratiques; "I do not regard that as natural!", et vous?
To see this story with its related links on the Guardian Unlimited site, go to
www.guardian.co.uk
Blanc check for wine purity
Suspicions that characteristic hint of gooseberry and green peppers in sauvignon might be aided by chemicals Felicity Lawrence, consumer affairs correspondent Friday January 23 2004 The Guardian
It is the hints of gooseberry and green pepper that wine critics look for in a good bottle of sauvignon blanc. But the taste may no longer tell the whole story.
British retailers are quietly testing wines amid suspicions that the characteristic flavours owe as much to chemical flavouring as to the natural taste of the grapes, the Guardian has learned.
A laboratory used by the drinks trade to test wine for authenticity has revealed that it has found suspicious results in several wines from South Africa on sale in this country.
Corkwise, a company of analytical chemists based in Surrey, confirmed that it had been asked by many of the major retailers to test sauvignon blancs from South Africa and New Zealand to establish whether synthesised pyrazine flavourings had been used.
Pyrazines are a group of chemicals which are found naturally in sauvignon blanc; the levels can vary according to climate and geography. Since synthesised flavourings may be "nature-identical", it is very hard to detect whether they have been used illegally to improve the taste of wine.
But Geoff Taylor, director of Corkwise, said his laboratory's results showed unusually high levels in wines across the price range from South Africa. Tests on wines from New Zealand did not show anything unusual. However, proving that unusually high levels of the flavouring compounds resulted from their being added by winemakers was difficult.
"The problem is that these chemicals occur naturally," he said. "You are looking for higher levels than normal, but who can prove that something unusual didn't happen that year in that vineyard? Maybe there are some very unusual sites that produce these very high levels of pyrazines."
Allegations that the use of industrial flavourings was widespread first surfaced in South Africa last November. Michael Fridjhon, a wine critic, wrote in the magazine Business Day that ranges of fake flavourings were being used to give the characteristic green pepper nose to cheap sauvignons, that blackcurrant flavouring was used in cabernet sauvignon, and butterscotch in chardonnay.
The South African Wine and Spirit Board has admitted that it "had been aware of the global practice of adding flavourants to wine" and that it had been conducting research with Stellenbosch University to establish typical profiles of pyrazines in sauvignon blanc so that cheats could be detected. The profiles are due to be published next week, although the results will not pinpoint individual producers.
Meanwhile, the vintage from some wineries in South Africa will be tested randomly, with results being collected from the grape juice straight after harvest and again after the wine has been made.
"We are not really sure what is happening," said Andre Morgenthal, spokesman for Wines of South Africa. "The research has been conducted with institutes from seven other countries because people in the trade have been suspicious about wines. It is a harmless food flavouring being used, so it is not a safety issue, it is more an ethical issue." He added that he thought only a few producers were involved.
But Robert Joseph, editor of the Good Wine Guide, said that the practice was probably more widespread. "People in the trade talk about international flavouring companies offering plum for merlot as well as gooseberry for sauvignon at wine trade fairs." These may legitimately be used to make low-alcohol flavoured drinks but are not permitted in wine.
Winemaking has been revolutionised in the past few decades. As well as making great advances in hygiene, producers have developed sophisticated laboratory techniques to blend wines and achieve consistent products.
Mr Morgenthal pointed out that sometimes the boundaries were blurred. "There is the assumption that wine is a natural product, that it is fermented juice with nothing added. But people add powdered tannin to fix colour. In the northern hemisphere they add sugar. Is that adulteration? I don't know."
Linley Schultz, the Australian head of the South African wine group Distell, condemned the use of flavourings, but told Decanter magazine that sometimes the distinctions were fine. He described experimenting while working for the Australian wine giant Southcorp with removing pyrazines from a batch of unripe sauvignon blanc grapes and blending them with a batch of top wine that had been harvested fully ripe but had lost some of its trademark asparagus notes. "I regard that as natural," he said.
Corkwise said it was unable to identify which retailers had asked for tests or which wines were involved on the grounds of commercial confidentiality.
Copyright Guardian Newspapers Limited
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