So many fires are burning in the Pacific Northwest that many winemakers have reasons to be worried about smoke taint on grapes that would transfer into wine. In the past, smoke taint has been a problem in California and in Australia so we know there is a high probability this will to happen to us as well. There is no doubt that vineyards close to fires that have or will be surrounded by thick smoke for an extended period of time will have tainted fruit – especially if the exposure to smoke is close to harvest. Red grapes made into red wines are more of a problem for smoke taint as the contaminated skin is put in contact with the juice for a few days or even a few weeks to extract color and tannins.
Luckily, at this point Pacific Rim is not worried about smoke taint because our vineyards have not been affected. Wallula Vineyard, source of a third of our Riesling (and of most of our Cabernet Sauvignon for Silver Totem) is in a windy location where no heavy smoke has set. Our other main sourcing region is the Yakima Valley which has been free of heavy smoke. It might be an entirely different story for wineries sourcing fruit in Lake Chelan, the southern Okanagan and possibly some area of the Columbia Gorge and central Washington.
We taste juices from grape maturity samples and visit vineyards regularly at this time of year and so far have not tested anything smoky or tainted. Traditionally smoke taint is characterized by high levels of 4-methyguaicol (smoke, char) and guaiacol (burnt wood, ashtray), those same compounds are found in barrels that have had a heavy toast; although, in the case of smoke taint, the levels are annoyingly high. We will likely send samples of grapes to an outside laboratory for analysis to double check the level of taint in our grapes. We will double check a few scout blocks (one in the Yakima Valley and one from Wallula) to make sure there is no taint that is left undetected by taste and could be revealed later in the wine itself (there are evidence that smoke taint might be bound with di-glycoside in the berry making it undetectable when tasting fresh grapes).
Should any block become tainted, we would first ask the grower to spray the clusters with water to knock down any smoke taint outside the berry. In the event of machine picking, we would remove leaves to avoid further contamination of the grapes. Any contaminated load would be kept separate and not blended into larger batches. Then we always have the option to do some membrane treatment to remove smoke taint but I have not heard many good results with the treatment.
So far so good for us – but surely we need to keep an eye on the situation.