We have learned a lot about smoke taint, but much mystery remains, and much currently widely held belief is likely false. For example, two eminent carbohydrate chemists in our working group, Wesley Zandberg of UBC and Kerry Wilkinson of U. Adelaide have independently determined that glycoside-bound forms of cresols are quite stable and do not hydrolyze, despite many claims to the contrary. It is true that post-RO treatment, smoke aromas will often return, but the source and mechanism are unknown.
The list of known compounds involved in taint is, in my view, quite incomplete because treatments highly effective in removing taint do not show much change in these compounds. Further, the aggressive parch on the front of the tongue is not likely to be caused by bound forms because they are present in very small quantities insufficient for cooperative binding to salivary protein.
Here is basic information you can look over. Begin with my article from WBM 2018 “Fire Down Below.” Right now we must take action despite imperfect knowledge. We have to concentrate on what seems to be working. It will likely be a long time before we know what the chemistry really is, if we ever do. I don’t want to waste too much time on the call speculating about the chemistry. “Understanding is the boobie prize.”
As of September 1st, we have largely come out of a month of highly unusual lightning-induced fires and are in a lull until high winds may bring on the electrical spark-induced fires we are accustomed to. Now may be a smart time to apply barriers to protect your grapes when that season hits.
Prior to a smoke event, kaolin seems to form a protective barrier to smoke, as does Parka. See the study from Wesley Zandberg’s group at Univ. of British Columbia showing an 80% decrease in smoke in Pinot Noir when applied seven days before the smoke event. Parka may do more harm than good if applied after the taint is present, but it is also possible that it can seal in the taint on the cuticle, allowing us to extract color and tannin and press early. Without Parka, we know this doesn’t work. Parka has many other benefits and is recommended to be applied at least three times per season: Once post set to minimize shatter, once at veraison as a block to sunburn and to prevent berry cracking, and once near to harvest to minimize desiccation and raisining. It’s very cheap: $35 per acre per spray and is green-friendly.
Many growers try to rinse or blow off ash. I haven’t seen any studies about whether this works, but it couldn’t hurt to try.
Grape testing at ETS for free guaiacol on grapes is a reliable indicator of smoke damage (except for Syrah, which naturally has high levels). Free guaiacol over 0.5 ppb is a useful index of smoke exposure, though not a taint in itself, as Scotch Whisky runs 3,000 -4,000 ppb. The actual taints are largely unknown. In my experience, red wines from grapes with over 1.5 ppb are very difficult to treat, so it is wisest to draw rosé off as quickly as possible, which may later have color added to maintain its appellation as a red wine.
Unfortunately, in 2021, ETS was quite quite backed up and results taking several weeks. Unless you have your own lab facilities, this analysis will not help you decide whether to apply Parka or whether to pick. UCD has recommended an Australian protocol for microvinifications. Even if you aren’t going to pick, the data from these may help you substantiate a crop insurance claim.
If you intend to make red wine from grapes, carefully remove all Material Other than Grape: leaves and other plant materials.
Italian-based Purovino has been providing ozonation services since 2017 to clean grapes, destroy Lactobacillis kunkeei (which causes rampant VA and resulting sticking in fermentations) and for reducing or eliminating sulfur dioxide. Several users have reported preliminary results that ozone treatment of grapes removes 50 to 80% of smoke taint in resulting wines.
Many wineries are developing vinification strategies to pick early. Co-pigmentation strategies and technologies such as Flash Detente, DTMA and micro-oxygenation can assist in enhanced extraction of higher pectin fruit.
Draw off as much saignée as you can and treat separately, making the most concentrated red you can – lots of Bois Frais Pumpable, maybe some Petit Verdot, etc.. After this is treated, you may elect to recombine the rosé once you see what you have.
For juice prep, use a phenol-specific carbon such as FPS from BSG. Other fining agents include Polyclar VT and a red-friendly bentonite, Mastervin Compact. Smartvin Carb from Vason is a pelletized carbon that settles well and is very effective at the juice stage but not as good as traditional carbon on dry wine. Enoblack Pearlage is a good fining agent for white wines and rosés but takes out a lot of color. Post-fermentation Enartis has a Fenol Free, another phenol-specific carbon which is a powerful agent that should only be used after running trials on the dry saignée fraction (do not use this on reds).
During red fermentation, select a yeast that produces high levels of red fruit aromas. Examples include Enartis Red Fruit and Alchemy 4. There are many other choices. Keep the press fraction separate. Rack early off gross lees.
Another approach to the problem is Flash Détente on must, with does remove a portion of the smoke taint and produces wines with considerable fruity amyllic esters which help mask taint.
When it’s time to treat, the first thing is to clarify the wine. Much of smoke taint is in the suspended solids. Centrifugation, crossflow, DE filtration (I prefer the DE alternative, Vitacel) are all useful. For red clarification, Mastervin Compact is a red-friendly bentonite clarifier.
I have been very impressed with the taint-specific adsorbent SRx developed by Jeff Murrell at VinSci. His adsorbent is provided as a service for a flat rate of $1.85 per gallon, and I have used it with great success. Send him two 750 ml samples and he’ll do lab scale demonstration at no charge.
Prior to treatment with RO or Spinning Cone, use Zimarom to wine at 60F exactly three days before treatment with either the Conetech process or Winesecrets method 2.0 UF/RO differential process, which provides a test track so you can try before you buy. Both processes are good at removing smoke aroma and the ashtray finish, so the trade-off is between removing the acrid parch in the mid-palate and preserving a sweet core of fruit. This is why you want to make the biggest, fruitiest wine you can. In the case of Conetech, this trade-off is extremely sensitive to flow rate, which must be painstakingly dialed in. Both of these processes continue to be refined, and since we are still in the dark about what exactly they do, it pays to take a buyer-beware openness and an understanding that there are no guarantees. It’s similar to an experimental drug for cancer. What have you got to lose?
Post-treatment mitigations that have proven useful include aromatic woods like cherrywood chips (for reds) and acacia wood chips (for whites and rosés) from Toneleria Nacional and the Oak-Wise Special Fruit (red fruit aromas) and their neutral finishing tannin E-Fresh, which does a good job of masking smoke taint. BSG finishing tannins such as Premium Limousin SG, but not mocha-like products. What doesn’t work very well is vanilla and heavy toast oak, which generally enhances the smoke and makes it worse, but oak alternatives are still worth a trial. It’s easy to do trials with all of these before adding to the finished, treated wine.
An extensive library of articles and research papers is available on my website. You can get there by clicking on the Theory tab at PostmodernWinemaking.com and scrolling down to “Smoke Taint,” which is an explanatory page with links.
My Dropbox contains the articles themselves.