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Contact Seeding for Cold Stabilization

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cold tanks in a facility

By: Tom Payette, Winemaking Consultant

Potassium Bitartrate Stabilization

  During the winemaking process and before bottling, there may be instability with a juice or wine termed Tartrate Stability or Tartrate Instability.  Unknowing customers often view these crystals as a fault and are therefore unsure of whether or not to consume the wine.  Once a customer is turned off by sediment, such as a tartrate precipitate, it may be difficult to get them to return to your label.  An in depth discussion below is to help winemakers achieve desired results in their cellars not undesired results in their bottled wine!  Winemakers are encouraged to make sure wines are bottled that will be sediment free.

Mechanism

  Tartrates are, very simply, a chemical salt made when potassium and tartaric acid combine making cream of tarter.  This cream of tarter [Potassium Bitatrtate] is harmless and is used, in the refined form, to cook meringues.  When most grapes arrive on the crush pad there is often a significant quantity of tartaric acid and potassium available in the grapes to result in instability.  Furthering the complication is the fact that the crystals are encouraged out of solution, forming further precipitation, in the presence of alcohol.  The fact that the winemakers have completed a successful fermentation will only force more of the crystals to precipitate. The processes to remove these crystals are largely a time temperature relationship.  Over time, and at low temperatures, most to all of the tartrates will form and fall out of solution.

3.65 pH Bifurcation *

  A very interesting phenomenon does exist with tartrate stabilization in wine made from grapes that all winemakers should understand.  (This may not apply to fruit wines) For a wine above a pH of 3.65, one should expect the pH to rise as tartrates form and fall out of solution.  For a wine below a pH of 3.65, the pH will drop to a lower pH value.  The shift, of the pH, is usually about 0.06 pH units but it can go as high as 0.19 pH units.  This knowledge can be used, factored into and forecasted by the winemakers’ ultimate plans for a certain wine’s final pH.

Tartaric acid and pH relationship

  Noting the example above, one must understand another relationship.  In both examples, whether the pH rises or lowers during tartrate stabilization, the tartaric acid level will decrease in the wine as it has formed in a salt and precipitated.  The tartaric acid has formed with potassium and become insoluble at that temperature during that time.  If the wine were to warm, however, the salt could re-soluablize negating the above statement.

Temperature and Potassium Bitartrate Formation

  As noted previously, the precipitation is largely influenced by a time temperature relationship.  Wine allowed to store over long periods of time will most likely achieve stability and it can be bottled.  With the advancement of sophisticated chilling systems in the wine industry, another process can be used.  Wines were often chilled for two to three weeks at 27 degrees F and allowed to drop their tartrates during this time.  This process was often successful but it did have its failures due to complexing agents that prevented the tartrates from forming.

Contact Seeding

  Perhaps contact seeding is more widely used today especially with wines that are blended late in the winemaking process or for getting younger wines ready for bottling sooner.  This process rarely fails and it does allow acid additions to be made even hours prior to using this process.  Some winemakers claim this action can be intrusive and beyond gentle processing; yet, others would have it no other way.

Procedure

  For those interesting in contact seeding, a procedure follows.  One must have an adequate chilling system, mixer, tanks that have little temperature stratification and a filtration system that can filter reasonably rapidly.  A properly sized plate and frame filter is sufficient for most winemakers while using a pore size pad of roughly 7 microns.  It is assumed the wine is clean enough to go through the filter pads without clogging and at a rate that will not allow the wine to warm too much potentially redisolving the tartrates previously formed during the filtration process. It is best to always check a wine first to make sure the wine is unstable before proceeding with this process.  One may be able to eliminate this process if the wine is already stable.

1.Chill the wine in need of stabilization to approximately 27 degrees F or potentially lower if the alcohol level is high enough and if greater stability is desired.  The wine will be stable at the seeding temperature of the wine at seeding so this temperature reduction step is critical.  (In the unusual case that the wine is below 8% alcohol, one would not want to chill the wine this cold.)

2.Start to mix the wine with a Guth or Keisel style tank mixer after the desired temperature has been reached.  Wait until the wine is thoroughly mixed and then double check that the desired wine temperature has been achieved and holding.  (Mixing may be done in a non-splashing pump over fashion with a pump, or two, that does not bleed any air into the system)

3.Weigh 3.0 (three) grams of Potassium bitartrate for every liter of wine in the tank.  Example:  for a 5000 liter batch of wine we would weight out 15000 grams of potassium bitartrate or 33.0 pounds.

4.Mix this amount of cream of tartar in water or wine before adding it to the tank.  (This step may be avoided but make sure no clumps exist in the cream of tarter and understand a larger quantity of oxygen may go into the wine if the substance is added dry)

5.Add the cream of tartar mixture to the chilled wine while mixing and mix for 3.0 hours or longer.  Make sure all the cream of tartar stays in solution and settling does not occur.  Make sure the temperature has remained at the desired level, as well, during this process.

6.After the 3.0 hours, mixing may stop but the chilling must remain on and continue to hold the desired temperature.

7.Allow the wine to settle overnight, or longer, if keeping the wine cold is not a concern.  [Recent research has shown an additional three days at 27.0 degrees F will improve the final conductivity results favorably on the wines.]  The wine could remain in contact with the seed for months as long as the temperature of the wine is not allowed to rise. After the overnight settling period and when filtration is desired. 

8.Vent the tank and start from the racking valve filtering on coarse filter pads making sure the filtration will go rapidly.  (One may want to remove any sediment “plug” first out of the racking valve by purging into a bucket before starting filtration.)

9.Continue to filter very cold into a clean, tartrate free, receiving tank.

10.Filter down under the manway door to the bottom of the tank as any filtration would be performed making sure to get all of the wine possible out of the tank.  Leave the solids behind.

11.If using water to push the wine through the filtration system keep in mind these crystals are water-soluble.  Make certain to use cold water and very limited amounts to not redissolve the cream of tartar making the wine unstable once again.  Do not dilute the wine with the water.  Perhaps consider using CO2 or nitrogen as well.

12.It is recommended to purge or sparge the receiving wine tank with Carbon Dioxide and the tank headspace of the wine tank being filtered during this process to eliminate or reduce the potential for oxygen uptake.  Other gases may be used such as nitrogen or argon.  (Keep in mind the principal that gases are more easily dissolved into a cold liquid solution during this step.)

13.Once the filtration is finished one may allow the tank of wine to warm and a representative sample of the tank’s contents may be taken to test that the cold stabilization action was successful and completed as desired.

14.Always double check the stability of the wine just prior to bottling and remember if more tartaric acid were added – the wine may become unstable once again.

Time / Energy / Quality

  The above process works very well to achieve cold stability.  The cream of tartar needed does have a cost factor yet the payback may be in the limited cooling cost for shorter periods of time during this process.  Others argue this process is damaging to the wine and it is over production on wine to support chilling a tank for 14 days or more.  This process will often work, yet the longer a winemaker stores a wine at cold temperatures – the more chance that the same wine will take in more dissolved gases.  This greatly increases the chance for oxygen uptake and potential oxidative reactions with that wine causes further damage.  Much of the above is determined by how each winemaker handles his or her wine and each factor should be considered.

Calcium Tartrate Stability Unaffected

  The reader should keep in mind that the process of cold stabilization in this manner does not necessarily affect calcium tartrate stability and many of the lab tests to check stability will not measure this form of instability either.

Miscellaneous Pointers:

  The winemaker must keep in mind that wines blended after cold stabilization must be reestablished or at least checked to determine their stability.  Two cold stable wines blended together will not always result in a cold stable wine and most often will reveal an unstable wine due to the chemistries of each wine and their resulting blend.  This may even be true with same blends cold stabilized separately.

  Make sure when purchasing the seed that it comes from a company that is aware of your use.  The cream of tartar seed size needs to be small enough to make sure the crystals have the proper surface for the seeding to be effective.  The seed particle size is best at 35 micrometers.  This will give the fastest rate of precipitation and growth.  A mix between 30 and 140 micrometers will do fine for this operation and is most likely the size mixture found commercially.

  One may re-use the seed from tank to tank using on whites first and then on reds.  If the seed is used in conjunction with bentonite, after cold stabilization has been achieved, then the seed must be retired.  This re-use of the seed may greatly drive down the cost of the seed per gallon as one moves it from tank to tank.  [The author has used one set of seed for over 40,000 gallons (8 – 5000 gallon tanks) of wine with success and has not experienced a failure of the process]  Cross-contamination is less of an issue at this time because the wines are generally moving toward filtration and bottling in stainless steel tanks or equivalent for sanitation purposes.

  Ion exchange and cross-flow filtration are rapidly approaching our industry.  These processes can be used to obtain cold stability should your winery have the technology and equipment to do so.

  In step three above the author has had success reducing this amount to 2 grams per liter as long as the wine is clean, chilled properly and at a desired cold temperature.

  Common sense tells us that if we can do this process in the winery, during colder winter temperatures, our chilling systems will be more effective and the cellar temperature will be more conducive to the complete process.  This applies to the filtration and making sure the wine does not warm too much during filtration.

  Be careful when rinsing the tank after filtration.  Ice may fall!

Summary

  This is just one method of achieving cold stability for a winemaker working with grape based wines.  Other ways are successful and may achieve the same results just as well.  Each winemaker is encouraged to try the process that works best for them and their particular cellars.  This process does have the quality of shorter chilling time and reduced utility bills plus faster turn around time for a specific wine – should those goals be desired.  Recall non grape fruit based wines may perform differently.

*  The 3.65 Bifurcation term was not located in any research literature by the author and it is a term the author has used to describe this phenomenon in his cellar work.

  Tom Payette, Winemaking Consultant, has over 30 years’ experience with winery start-ups and assisting wineries already established in the industry.

PerCarb® – Dual Mode of Action for Effective Disease Control Management on CA Wine Grapes

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biosafe systems

EAST HARTFORD, CT – PerCarb is an EPA-registered contact foliar bactericide/fungicide with residual activity designed to treat and control plant pathogens on a wide range of crops. Its formula consists of odorless, sodium carbonate peroxyhydrate granules that provide superb coverage on a crop’s surface. PerCarb kills foliar pathogens on contact while inhibiting fungal and spore development through changes of pH and osmotic pressure of microbial cells. This dual mode of action is especially useful when combating powdery mildew commonly found in vineyards.

per carb

PerCarb is also an excellent component of any well-rounded IPM program. For vineyard applications, it is recommended to rotate PerCarb and OxiDate® 5.0 for complete foliar disease control. Both formulas work harmoniously to completely eradicate pathogens, ensuring healthy and flavorful grapes with every harvest.

For any questions or where to find PerCarb in your area, call BioSafe Systems at 888.273.3088.

About BioSafe Systems, LLC

BioSafe Systems, LLC are innovators of environmentally sustainable practices and products since 1998. We provide solutions for protecting crops, water and people. Customers, researchers and regulatory agencies have remained at the forefront of our success and willingness to adapt to the ever-changing world around us. BioSafe Systems is a family-owned company whose products are proudly manufactured in the United States.

 22 Meadow Street
 East Hartford, CT 06108
 Phone: 860.290.8890
 Fax: 860.290.8802
 www.biosafesystems.com

www.biosafesystems.com

Handling That First Crush

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Closeup of wine grapes being dumped from a truck into crusher
Closeup of wine grapes being dumped from a truck into crusher

By: Tracey L. Kelley

The anticipation of your first wine crush is a different kind of love story. Waiting for this moment to come to fruition requires years of planning, plotting and production. If you’re a grape grower, your pulse quickens with vérasion as the potential presents itself. If you’re a winemaker relying on partnerships to provide you with grapes, the sweat on your brow is both excitement and a little anxiety until you know everything is just right.

  How can you speedily process grapes while enjoying the journey of this process? Choose the right equipment, craft a solid contingency plan and ask the right people for help. Every year provides a chance to reassess, but in most cases, each crush will be better than the last when you know what works for you.

What Crushing Process Works Best for You?

  In some business plans, scaling your equipment to a larger level at startup is often the recommendation so you’re prepared for projected growth. However, if your winery goals require you to stay small, at least until expansion possibilities solidify by demand and profitability, there’s no need to have volunteers for foot treading or hand-cranking grapes—unless that’s part of your marketing and promotions efforts, of course.

  Many small and mid-sized producers benefit from automation. Leo Birdsall is the inventor and owner of FASTRAK Cider Press, based in Springfield, Oregon. He developed a press powered by an air compressor that handles destemmed or shredded fruit. He said he got the idea from talking with producers at trade shows who wanted a motorized method for crush with a lower price point. The automation also helps reduce labor.

  “You can have one person operating the destemmer, feeding the clusters into it. Then another person can collect the pomace in a bag and put it on the press. Once the press is activated, it takes 2.3 seconds to get about three–to–four gallons of juice,” Birdsall told The Grapevine Magazine. Depending on your flavor profiles, you choose how much pomace set aside and add to the juice during fermentation.

  The average price of mechanized destemmer crusher is approximately $3,800–$5,500, especially if you want features such as variable speed control and hookups for must pumps. A wine bladder press is often two times that amount. If your operation is processing about one ton of grapes at a time, as an example, averaging 120–150 gallons of wine per ton—or roughly 60–65 cases of wine—it’s easy to see why even a small automated system makes a speedy difference during crush season.

  FASTRAK retails for $2,500, so paired with a hand-powered or motorized destemmer with an estimated price of $350 might be a more comfortable entry point for some small producers.

  Other producers may find high-quality destemmer crushers at auction, then learn how to rebuild and repair the equipment and save costs that way. Michael and Kelly Amigoni own Amigoni Urban Winery in Kansas City, Missouri. Winemaker Michael specializes in dry wines crafted from Barbera, Cinsaut, Sangiovese and Tempranillo grapes. Although the couple once had a vineyard, Amigoni now receives 70–90 tons of whole clusters from their partner growers in Lodi, California. They crush, press, ferment, barrel-age and bottle at their winery in the revitalized Stockyard District of Kansas City’s West Bottoms neighborhood.

  Amigoni’s initial production started with 300 cases. Twelve years later, the winery produces more than 4,000 cases a year of award-winning cabernet sauvignon, cabernet franc, chardonnay and viognier.

  “We have a rebuilt French crusher destemmer that we bought at auction, and we rebuilt the motors—one that propels the destemmer, and one that propels the crusher rollers. We tore the guts out and rebuilt it all,” Amigoni said. With this machine, he can crush about three tons in an hour.

  Machines with gentle overlapping lobe roller crushers continue to be the most prominent choice for small–to–mid-sized producers. Ultimately, a winemaker has to choose a machine that allows for more control over color and tannin. Equipment with variable speeds might enhance the process not only for production but also final quality.

Get Your Equipment and

Supplies in Order

  On average, you have a day—maybe two—to crush grapes. Checking all equipment now is critical to ensure efficient process flow. Inspect, repair and prep:

•    Destemmer, crusher, press, pumps, bladders and hoses—make sure to only use food-grade grease, paint, and cleansers for oiling, metal coating and sterilization. Check seals, bearings, paddles, clamps and hose integrity. You’ll also need a special bladder cleanser. Double-check that you have all the necessary lubricants

•    Buckets, bins, hold tanks, must chillers, fermenters and barrels—pressure wash as needed and sterilize. Check tank fittings and valves.

•    Crush pad and winery—fill cracks and low spots, sanitize for mold and other foreign material.

•    Forklift—even if it’s a rental, run the machine a few days before crush and check the operation. You’ll also probably need extra gas canisters, so call the gas company and have them on hand.

•    Refractometer—use distilled water to recalibrate it to ensure proper brix reading levels.

•    Brooms, mops and other cleaning supplies—have two or three sets so workers don’t have to wait to use them.

•    Hot and cold water options—you’ll need to check your microwave or kettle to make sure they’re working to warm up water for optimal yeast temperature. Check all nozzles, faucets, and sprayers.

•    First aid kit—plan for every medical emergency, from a minor bee sting to a slip and fall, and stock accordingly.

  Amigoni is a careful planner. This technique, he said, helped reduce the pressure of crush. His checklist is quite extensive, and he adheres to it. “I used to panic before harvest,” he said. “Now, I don’t. I’ve seen it all over the years, and realize preparation is everything.”

  Proper gear such as boots, raincoats, and pop-up tents, Amigoni said, make it easier to crush outside. Have a few extra sets of gloves, safety glasses, and masks beyond the number of workers you’re expecting to prepare for any contingencies or additional people stopping by to watch the process.

  “Make sure you have enough covers for open bins and tanks, too—even heavy-duty cardboard is fine. I get extra cardboard from a local brewery. Also, be sure you have enough tape. You never have enough tape,” he said. “If it’s windy or there’s a hose problem or whatever, tape solves a lot of problems.”

  Order about 10% more cleaning and lab supplies than you think you might need—many will keep for a full year. For example, Amigoni said, get a few extra packets of the highest-grade yeast to have on hand.

  “You order yeast according to your variety, but there are times when you have high brix, and normal yeast will die at 16, and maybe you had something come in at 28 or 30 brix,” he said. “Make sure you have high-quality yeast that will go to 17, just one or two packets sitting by, because if you need to have yeast overnighted, it’ll cost a lot more.”

  “Additionally, if you’re doing a cold soak technique, make sure you’ve lined up your dry ice. If you’re using a jacketed tank or chiller, have plenty of glycol available in case there’s a leak or if you need to add some to get down to a certain temperature.”

  Like many winemakers creating different styles, Amigoni has a staggered crush season: a hurry and wait on each varietal’s arrival over the course of a few weeks. He’s learned proper preparation before each crush is essential. “If you’re not prepared, you’ll implode. You have to be precise. I’ve seen times when we’ve spilled things or hit things because we’re in a hurry. This rushing causes a ripple effect, and it’s detrimental to your whole operation. Preparation helps the whole process run more smoothly.”

Create an Environment of Joyful Work

  Crushing is often at its best when it’s done “in kind,” Amigoni told The Grapevine Magazine. “Along with a couple of regular workers, we also have quite a few people—typically 12 people—who volunteer. We have some people who come back each year, and actually, have a waiting list of others wanting to help. They get paid ‘in kind,’—kind words, kind people and a kind smile when you say ‘here, take this home’ as you hand them a bottle of wine.”

  However, he recommends being discerning with who does what. “My biggest challenge is sorting through people and putting them on the right task. Only certain people go on the crusher, for example, or only a couple of people can operate the forklift. Maybe others are marking bins, or putting together little buckets of stuff for me, taping stuff. They like helping, and everyone has a purpose.”

  His advice for getting through your first crush, and others, is threefold:

1.   Pace yourself. “You’ll have a tendency to think ‘I need to do everything at once!’ and rush through everything. Most of the time, though, grapes can sit for a day or so.”

2.   Take the proper amount of breaks. “You might want to push through the whole day—12 hours or more without any breaks—but it’s better to tell your crew to stop, have no equipment running and sit down. Have burgers or pizza or whatever and talk for a while. Your productivity goes through the roof afterward. I used to have a bad habit of not stopping—it took me a long time to find the value in that. It’s not right to push everyone so hard. So make a point to say, ‘Okay, that’s a half-ton done. Here’s your next one waiting when we come back. Now let’s all sit down and eat.’ You can time it—a half hour or so to rehydrate, eat and relax. It may take some volunteers a little longer to get up than others, but they’ll get up to speed eventually.”

3.   Always remember to have fun. “People say, ‘What do you think about your job?’ and I say, ‘I don’t have a job.’ In the early years, yeah, it seemed like a little more of a struggle, especially when I wasn’t prepared. You’ll run into a sweet spot eventually—your budget will increase, you’ll get better equipment and continue to keep yourself motivated.”