While the start of the serious rainfall here in California (hopefully) marks the end of fire season and smoke-taint risk, there is still a significant amount of fruit that has not yet been harvested, particularly in the cooler coastal regions like Monterey. Unpicked fruit now faces an increased risk of Botrytis and other rots, especially if the rains continue and it becomes difficult to get harvest equipment into the vineyards. The ATPGroup team has some suggestions on best ways to handle grapes infected with Botrytis Cinerea:
Assess the Damage
Check the infection rate of your fruit and have the laccase levels of your wine tested if you are concerned with residual levels. Dose recommendation ranges given below are for low to moderate rates of infection (5%–10%). Lots with greater than 20% infection may require additional measures. Please contact our technical team with questions on handling these extreme conditions.
Pick it Cold
The lower the temperature of the must, the less Botrytis-related enzyme activity there will be.
Up the SO2
Add 80–120ppm SO2 as early as possible, preferably into the picking bins or gondolas when machine picking. This will help minimize oxidative and enzymatic reactions pre-fermentation. An addition of 0.4–0.8 lbs/1000 gallons of Vin-Chito will reduce the populations of spoilage microorganisms.
Inhibit the Laccase
Add 1–4 lbs/1000 gallons of Color-Tan plus 0.2–0.6 lbs/1000 gallons Gallic-Tan to red must or 0.4–1.2 lbs/1000 gallons of Gallic-Tan to white juice. Tannins are the most effective tool in reducing the effectiveness of the Botrytis-related enzymes laccase and polyphenol oxidase. There are various types of these enzymes, many of which are not affected by bentonite treatment at common wine pH.
Tannin addition rates tend to be linearly related to the laccase/PPO inhibition, so the more laccase/PPO activity, the more tannin you need. Care should be exercised as the Gallic-Tan, which is the most effective tannin for inhibiting the enzymes, is also quite bitter, so additions are best made to white juice before the pre-fermentation racking.
Consider Flash Détente
Processing reds (and whites) through TMCI Padovan’s Red Hunter Flash Détente System will completely denature the laccase and polyphenol oxidase enzymes.
Get Aggressive with the Polyphenols
Add 2–6 lbs/1000 gallons Phenol-Fine Plus NF to your white juice. This PVPP/casein/bentonite-based blend is particularly effective at removing the oxidized polyphenols (already brown) as well as removing potentially oxidizable polyphenols (before they turn brown). Adding to the juice prior to fermentation (after tannin addition) also helps with any residual astringency and minimizes any risk of stripping away aromatics.
Get it Clean
To minimize the time white juice is in contact with infected lees, a rapid and efficient settling is recommended. The bentonite component of the Phenol-Fine Plus NF will help improve the efficiency of settling. To maximize the rate of settling, 8–16 mL/ton Zyme-O-Clear Plus Liquid or 16–32 mL/ton Zyme-O-Xtra enzyme can be added. Note: enzymes should not be used pre-press on grapes affected by botrytis! Juices which have been highly clarified may require post-racking addition of clean lees or yeast hulls (Springcell™) for a healthy fermentation. Hard-press juice should be kept separate and will likely require additional treatment.
Be Quick
Ferment with 2.5 lbs/1000 gallons of a strong, efficient yeast strain such as Red Star Premier Cuvée, SafŒno™ BC S103, or SafŒno™ VR 44. As rots and molds can result in early scavenging of YAN along with micronutrients, having an aggressive nutrition strategy is important as well. Additions of DAP and SpringFerm™ or SpringFerm™ Xtrem should be made at up to 2 lbs/1000 gallons in stages through the early and middle of fermentation. For those wines in which malolactic fermentation is desired, up to 2.5 lbs/1000 gallons of Malo Detox to reduce ML-inhibiting toxins and fatty acids along with up to 2 lbs/1000 gallons Malo Nutribact ML nutrient will help ensure a quick and successful MLF. Rack off lees as soon as fermentation concludes to further reduce the possibility of residual infection.
Maximize Aromatics
Because pre-press enzymes should not be used, maximize your aromatics with a late-fermentation addition of 24–60 mL/ton Zyme-O-Aroma Plus liquid enzyme. Addition late or immediately post-fermentation allows you to bench-trial the enzyme to optimize your dosage and aromatic expression.
Check Filterability
The presence of Botrytis and other rots and molds can cause an increased concentration of glucans and pectins post-fermentation, which can significantly impact your filterability. To protect your expensive bottling membrane filters we recommend testing for glucans and pectins. If you see elevated numbers, treat with up to 0.4 lbs/1000 gallons Zyme-O-Glucanase enzyme (depending on bench trial results).
ATPGroup’s team of experienced enologists and technical specialists is always available to help design a custom program to fit your winemaking style and budget. For more information, please contact your ATPGroup Technical Representative or Enology Products Specialist, or call (707) 836-6840. Information on our products is also available on our website: www.ATPGroup.com.
ATPGroup was founded as a family business in 1991. Now a leading supplier to the wine, beer, food, and pharmaceutical markets, we strive to provide solutions and create value for our customers in each of the industries we serve. We offer an unparalleled range of high-quality products and services including winemaking & cellar products, brewery supplies, glassware, production equipment, cleaning & sanitation solutions, parts & servicing, mobile services, tartaric acid, cream of tartar, and Rochelle salt. The ATPGroup team is made up of industry veterans, engineers, cellar masters, and product specialists who provide technical expertise in their respective fields. Our multiple warehouses are strategically located across the country to serve customers throughout the U.S., Canada, and Mexico.