nigel groundwater
nigel groundwater
Jim,
I believe Don has followed and addressed [through the oxidised burgs wiki he edits, his extensive white Burgundy tasting events and general participation in pox-related threads] the issue of prematurely oxidising white Burgundy more assiduously than anyone else.
IMO the pox is indeed likely to have its origin in the convergence of ideas, desires and perceived taste imperatives which, around the mid-90s, resulted in changes in the way white Burgundy was made so that it became easier to drink earlier and [putatively] was also healthier and more ‘natural’.
Together these included changes in the way grapes were grown [increasing organic and biodynamic viticulture], when they were picked [riper], how they were sorted [new sorting tables removing damaged/unripe berries] and then pressed [new computer-controlled pneumatic presses producing cleaner, ‘lighter’ juice] resulting in higher sugar, lower acid musts containing [allegedly] lower natural anti-oxidants which were then treated [e.g. batonnage et al] to produce wines which drank well earlier than in the past.
On top of which SO2 additions were generally reduced [in some cases to zero] partly in response to the ‘health pressure’ from the [new] requirements for sulphites labelling but also because new sorting tables provided a higher confidence level that the need for SO2’s anti-bacterial properties would be reduced. Lower SO2 use also supported the ‘easier early drinking’ objective with fining and filtration also reduced or removed in line with the ‘more natural’ ethic.
It is tempting to see lower natural anti-oxidants, lower acidities and reduced SO2 usage as something of a perfect storm since the first obviously reduced a wine’s natural defences against oxidation while the other two reduced the anti-oxidant efficacy of SO2 compounding the effect of the lower amount added. A potential triple whammy. Oddly 96 was a high acid year but perhaps that simply tempted producers already gung-ho on SO2 reduction to push the envelope even further. There are certainly reports of some producers promoting their minimisation of SO2 usage in that vintage and as I type this I am also reminded of the late, great Didier Dagueneau's [bad] premature oxidation experience when he pushed his already low SO2 usage too far.
Of course corks were also changing as suppliers moved away from hypochlorite bleaching to hydrogen peroxide [because of the TCA implication of the former] and altered the coating treatments from paraffin wax to silicone wax either as a replacement or as an addition. And since hydrogen peroxide is a natural oxidant within normal wine-forming chemistry and a ‘leaky’ closure a known historical cause of premature oxidation, an early theory was that the pox was essentially a cork-related phenomenon allied to some residual H2O2 from the cork bleaching treatment. Added to which was the possibility that the silicone surface treatment had reduced a natural cork’s ability to seal a bottle. Another potential triple whammy.
However as you note some early studies [e.g. the Beaune Study in June 2007] concluded that cork treatments were not the cause of the pox although there are still some who believe that the quality of the cork closure has played some or even the major part in the pox phenomenon looking to e.g. wax seals placed over corks to counteract it. Or pointing at those with a low incidence of the pox that have were already wax-sealing their wines.
Some producers have turned to DIAM and others to screwcap although the latter probably had part of its earlier rationale in the avoidance of TCA despite the improving performance of natural cork in that regard.
While natural corks are likely to be a major factor [as has always been the case] in the differential performance of bottles in a case it may be that this simply continues as before but the incidence of the pox has actually advanced the overall oxidation timeline by years for all the bottles in a case and [possibly] altered the timing of the first to last occurrence.
I can think of at least one good Chablis producer who now uses natural cork, DIAM and screwcaps depending on the market they are destined for. IIRC William Fevre now use DIAM for all except their GCs although their prime counter-measure would appear to be a new bottling line and the mitigation of entrained oxygen one of the several possible pox factors thrown up by the research to date. In addition there appears to have been a significant general return by producers to higher SO2 levels in recent years according to various reports [Allen Meadows, Stephen Tanzer et al].
IMO the idea of winemaking changes being responsible is plausible for several reasons e.g. the event horizon is apparently well-defined from the mid 90s with the 95 and then 96 vintages providing a disturbing trend with bottles opened from 2002 onwards. However I would suggest that 2004 is probably the first vintage when even the most assiduous producer might have tried to deal with an issue that has still not been understood/resolved satisfactorily although [at least] some producers have taken steps to address what they believe was causing their wines to oxidise prematurely. Additionally there were the several ‘new’ ideas in viticulture and winemaking [mentioned above] that were being increasingly explored although not all producers were convinced or participated.
This latter point provided a major research opportunity that has been foregone because [allegedly] producers would not have been willing to provide the necessary information for legal and/or PR reasons. IMO if detailed research had been conducted with a significant sample of producers early, in say 2004/2005 when the phenomenon had started to be widely discussed, including those who appeared to be the worst and least affected, patterns of behaviour and resulting performance would logically have emerged that pointed clearly at the most likely and significant causes. If necessary [and it probably was] such research could have guaranteed the anonymity of the individual participants and been done by a University Oenology Department.
At least we would know precisely what happened to the timing and quantity of SO2 additions and why, to the commissioning of new presses and sorting tables and their impact on winemaking, and indeed to all the usual suspects AND have had some further information in the analysis from comparing what those producers whose wines have fared badly did with the practices [possibly unchanged] of those whose wines have been much less affected.
Finally, and I apologise to all for the length of this post, I wonder what will happen if there is a general conclusion that one cannot have one’s cake and eat it? That making white Burgundies that drink well young is largely incompatible with wines that will age well for many years. Hopefully the facts about the pox will be revealed but whatever they are the future is not clear.
As you say, "perhaps some of these on-going studies will be more helpful" but I wonder if they will change much.
