What is smoke taint and how do I know it is there?
The question of smoke taint is coming up a lot these days. Is it in the fruit? Will it affect my wine? How do I remove it? Based on 2008 experience, highly tainted fruit can make some very ashy, astringent, bacony wine (think of drinking red wine around a smokey camp fire). It is not one of those taints that is easy to mask or to treat.
The actual smoke related compounds seem to be bound to the glycosides in the wine. This has been proven in chemical hydrolysis reactions involving smoke tainted wine. The measured guaiacol levels in the wine after hydrolysis show a 2-8 fold increase in concentration – which is why there is this “return” affect within 6 to 12 months after treatment in some wines.
Treatment in the Juice Stage
The BIG question is how to deal with this problem. There are several helpful tools in dealing with it, but no “magical” cure. One option is to flash the recently harvested fruit (reds only) to remove as much smoke taint from the skins before it has a chance to integrate with the juice. It is suspected that the smoke taint is concentrated in the skins of the berry due to some interesting observations of the contamination process in 2008. Juice samples that showed little to no sign of smoke taint in 2008 resulted in highly tainted wine after fermentation and whites showed lower levels of smoke taint due to limited skin contact. Since the flash process wasn’t used much in 2008 to deal with the issue, we have limited knowledge on the success of this processing option, but if it reduces the guaiacol levels by more than 50% right off the bat, then you are half way through dealing with the issue.
Wine Stage and success of treatment
During fermentation, the level of smoke taint increases as the sugar is broken down during the fermentation process. As these glycosides break down, the smoke compounds are released. To find out if wine is contaminated, a guaicaol analysis will prove its presence and show the level of taint. This level can range from 4 ug/l to as high as 200 ug/l. Note this analysis needs to be done before any oak products are added to the wine and after fermentation is complete. VA Filtration was able to successfully treat wines with guaiacol levels of up to 80 ug/l, but beyond that, the results can vary dramatically. It is also known that the treatment has a 50% long term success rating. In around half the wines treated in 2008/2009, the smoke taint returned within a year. The levels were diminished, but it was definitely there. This return affect is again due to the break down in the glycosides, where the smoke taint compounds are attached, as the wine ages. A “fire” sale might be necessary if it is found that wine has smoke taint.
The Treatment Process
VA Filtration has the only patented NANOFILTRATION process for dealing with smoke taint. Using nanofiltration in conjunction with phenolic removal media, the guaiacol and related smoke taint phenolics are removed from the wine gently and efficiently. We successfully treated over 2 000 000 gallons of smoke tainted wine in 2009. This year we have dedicated machinery designed for rental or servicing in case of smoke taint.