Rutherford
Tannat.
33.6° Brix. Blackberry preserve. More than one direction.
Exceptionally juicy fruit, remarkable color and serious structure right off the crush pad. This vintage gives you room to make a powerful dry red, explore natural sweetness, or build a distinctive fortified wine.
McGah Family Heritage Vineyard · Block 3C · Rutherford AVA
Original ETS values · October 8, 2026 · View the analysis. Dry-red recipe: 33.6° → 25° Brix.
Exceptionally juicy fruit. Huge character. More than one direction.
We had a great time working with this Tannat. The berries were exceptionally juicy, and the juice had the kind of deep, ripe blackberry flavor that reminded us of blackberry preserves. There was a lot of color right away, along with impressive phenolics and structure before fermentation even began.
We knew it was concentrated, but seeing 33.6° Brix on the ETS report really got us thinking about what to do with it. You can water it back for a powerful dry red, lean into a naturally sweet style, try a fortified wine, or explore traditional red-wine blending trials. All of those are interesting, and we are excited to see what people make.
We're going to talk through the chemistry in detail, but we don't want the lab numbers to get in the way of the larger point: this fruit tastes good, and there are a lot of ways to bring that out.
Your First Rutherford Tannat: Just Tell Me What to Do
Want to make a serious dry red without having to become a winemaking chemist? This is our recommended starting route for the 2026 harvest. Pick one of the two yeasts we already use regularly—Enoferm RP15 or Uvaferm BDX—and work through the instructions in order. We'll explain the chemistry further down if you're curious.
A simple route from frozen must to wine
Thaw, then mix from the bottom up
Sanitize everything that touches the must and thaw the pail under clean, controlled conditions. Before taking a Brix, pH or TA reading—and before making any additions—mix the thawed must thoroughly from the bottom upward. Get your paddle or spoon all the way to the bottom and keep mixing until the pail is uniform.
With frozen must, sugar and acids become concentrated in the remaining liquid during freezing and collect toward the bottom as a clearer, denser layer. Sampling that layer—or sampling mostly from the top—can give you a misleading starting measurement. Once homogeneous, move the must to a primary fermenter large enough for the must, added water and at least 25% free space for the cap and foam.
Prepare the water and add the full tartaric one-shot
Use low-mineral water that is chlorine- and chloramine-free. Plain distilled water with no minerals added is the easiest option. Unsure what kind of water to use? See the water guide →
For one 5-gallon must pail at 70% liquid recovery, our WGD calculator calculates 1.20 gallons of water for 33.6 → 25° Brix. It then gives 27 g tartaric for water acidulation and another 16 g balanced one-shot to aim from pH 3.75 toward 3.60. Dissolve the included 43 g tartaric pouch in 1.20 gallons of clean, low-mineral, chlorine/chloramine-free water and mix thoroughly into the must. The 43 g is the total for these two modeled steps—not 43 g in addition to the 27 g. Use a suitable fermentation vessel with enough headspace.
Check the blended must and plan nutrition
After mixing the whole pail thoroughly, check Brix, pH and TA after about 1 hour. Treat that as an early reading because potassium buffering and the must's acid chemistry can keep shifting; when practical, a later or next-day pH is better for fine correction. The predicted 3.60 pH is not guaranteed. If the pH is still clearly high after remeasurement, use our main calculator to plan a smaller follow-up addition to the whole pail. The 43 g of tartaric has already been added in the one-shot and must not be added again. Original YAN is only 96 mg/L, approximately 71 mg/L after this water-back. Our RP15/BDX working recipe therefore includes both Fermaid O and additional DAP; recalculate if your measured YAN or volume differs. A pH goal alone does not replace SO₂ or microbial-stability management.
Prepare the yeast using Sterol Flash (NOT the old hot-water method)
Choose 5 g RP15 or 5 g BDX. Your WGD kit supplies 5 g Go-Ferm Sterol Flash. For that 5 g pouch, the Flash mixing ratio of ten times its weight uses about 50 mL of clean, chlorine-free water at or above 59°F (15°C). Follow the Flash pouch instructions for yeast rehydration and inoculation; the Flash rehydration period is 15 minutes. Do not put DAP in the rehydration water, and do not use the old Go-Ferm hot-water instructions. Supplier instructions ↗.
Use the kit portions; add DAP separately
Add the kit’s 5 g Opti-Red at the start. For the recommended dry-red route, add the kit’s 7 g FT Rouge near the start for early tannin and color support.
For the stated RP15/BDX dry-red example, use 5 g Fermaid O plus 10 g DAP total. Feed 2.5 g Fermaid O + 5 g DAP after a 2–3° Brix drop, then the same amounts at about one-third sugar depletion. Suspend each separately in a little clean water or must, then mix in carefully; fermenting must can foam.
No DAP in the yeast-rehydration water and no routine late DAP additions. If fermentation is already past one-third sugar depletion, do not catch up by dumping in both feeds. Contact us for a batch-specific plan. Adjust the recommendation when actual YAN, volume, yeast or starting sugar differs.
Ferment and monitor every day
Keep the fermentation within the selected yeast's recommended range (RP15: 68–86°F; BDX: 64–86°F); aim roughly 70–78°F as a controlled working range while respecting the selected yeast and avoiding overheating. Record temperature and falling sugar daily, keep equipment sanitary, and carefully wet the cap 2–3 times a day while fermentation is active. If the fermentation slows unexpectedly or smells strongly of rotten eggs, investigate promptly rather than waiting.
Press, finish, and age
Press once your dryness and extraction goals are met; avoid assuming “more extraction” is always better with Tannat. Transfer off heavy gross lees, decide whether to complete malolactic fermentation, then verify completion analytically. Control oxygen and sulfites based on measured pH and free SO₂. Allow the wine time to settle, age, and stabilize before bottling.
With the example 1.20-gallon water-back, 3.5 gallons of baseline finished wine and 75% of added water retained, the yield model suggests about 4.40 finished gallons—roughly 22.2 standard 750 mL bottles, versus 17.7 without water-back. That's an estimate, not a guarantee. We want a balanced, expressive dry Tannat; the additional yield is a bonus.
From Rutherford's Heritage Vineyard
Our 2026 Tannat comes from McGah Family Heritage Vineyard in Napa Valley's Rutherford AVA. It's from Block 3C, selection 1.1, planted in 2022 on 039-16 rootstock. Tannat is an unusual grape to find in Rutherford, and we were excited to have access to it this year.
The fruit was super juicy when we processed it. The ripe blackberry character was impossible to miss, and the juice already had really attractive color, phenolics and structure. This is the sort of raw material that makes you start imagining several different wines before you've even decided on a yeast.
That structure gives us plenty to work with, whether we're making Tannat on its own, using a portion in a Cabernet blend, or doing something less expected. We can also explore Cabernet- or Malbec-based blending trials, but the Tannat has plenty of character to stand on its own.
Juiciness, rich blackberry flavor and a strong backbone—not just the high sugar number. Getting the balance right will matter, but the fruit has real personality worth preserving.
This is why we’re excited about this year’s fruit.
We sampled the must right there on the crush pad. It was extraordinarily juicy, with a rich blackberry flavor—almost like a preserve—and a color that was already remarkably deep before fermentation.
The phenolics and structure were evident too. That gives us plenty of options, but it doesn't mean we want to extract as much as possible just because we can. The trick will be keeping that fruit character alive while making the wine balanced.
We can't wait to see what everyone does with it, from a dry Rutherford Tannat to a sweet, Italian-inspired interpretation or a distinctive Port-style bottling.
One more photo from the crush pad
Our first alcohol-free wine? Not quite.
We poured some of the unfermented Tannat must into a wine glass, and the color was so dramatic we couldn’t resist making a joke about our first alcohol-free wine.
Don’t worry. We have considerably more ambitious plans for the finished product.
A March trip to Frascati, and a very different Napa harvest
The Italian connection isn't just something we read about. It goes back to a trip with my wife, a visit to Frascati, and my first introduction to a different way of thinking about concentrated grapes.
A day out from Rome
My wife and I were staying in Rome and took an excursion to Frascati itself. It was March. We spent time at a winery, explored the cellar, looked out over the vineyards, and, of course, tasted the wine.
That visit was the first time I really learned about drying grapes to concentrate their sugars and flavors. It gave me something to think about long after we got home.
The equipment, the process, and the finished wine
I didn't see grapes actively drying on that visit. We were there in March. What I saw was the drying equipment, and I learned how they used it. Then I got to taste what they made.
The idea stuck with me: rather than depending entirely on what the growing season delivers while the grapes are still on the vine, you can work with the fruit after harvest to pursue a particular style. Seeing the setup and tasting the result made that much more real to me than reading a description ever could.
A hard cookie and a little sweet white wine
There was another local tradition I was happy to get involved in: dipping a very hard cookie into the sweet white wine to soften it. That's what I'm doing in this picture.
My wife and I came away with memories of the vineyards, the cellar, the wine, and a pretty good way to eat a cookie. It's a much better introduction to sweet wine than staring at a residual-sugar chart.
Amarone, Recioto, and Sagrantino
Frascati was my personal introduction. The wines below come from other parts of Italy, but they give us useful ways to think about what concentrated fruit can become. They aren't interchangeable wines, and we're not claiming this Napa Tannat is made from their grapes or by their traditional methods.
Amarone
Amarone della Valpolicella offers inspiration for a powerful dry red made from grapes concentrated through appassimento, or partial drying after harvest. That is a style reference, not a claim that our water-back method is how Amarone is made.
Recioto
Recioto della Valpolicella takes partially dried grapes in a sweet direction. It's an interesting reference for customers who want to preserve some natural sweetness in this Tannat, with a deliberate fermentation-control and stability plan.
Sagrantino
Umbria's Sagrantino is known for firm tannic structure and aging potential. Montefalco Sagrantino has both dry and sweet passito expressions; the passito uses dried grapes. It's another reminder that substantial structure can work in more than one style.
For someone drawn to the structure of Montefalco Sagrantino, this Rutherford Tannat is worth considering. We tasted rich blackberry character, deep color and a firm phenolic backbone in the must. Those are the qualities that make us excited about a serious, structured red from this fruit.
Tannat is a different grape, not a replica of Sagrantino. But when the appeal is a deeply flavored red with plenty of structure to work with, our frozen Tannat grape must offers an interesting alternative to explore. The comparison is about what you enjoy in a wine, not a promise that the two will taste the same.
For the Italian background: Consorzio Tutela Vini Montefalco on Sagrantino and passito, and Arnaldo Caprai on the grape's structure and tannins. Our Tannat comparison is our own winemaking interpretation.
This year, we didn't need the drying racks.
Last year, we couldn't have produced anything quite like this Tannat. The rain came, and there went the opportunity. I don't have generations of drying racks and an Italian winery set up to take over when the weather refuses to cooperate.
This year, our Rutherford Tannat arrived at 33.6° Brix, concentrated right on the vine—and it was exceptionally juicy. That brought me right back to what I'd learned in Frascati.
On-vine ripening isn't the same process as drying harvested grapes. What we're taking from that visit is the willingness to see concentration as an opportunity: a dry red, a deliberately sweet wine, or something fortified. We have some wonderful fruit to work with, and more than one way to bring it out.
Concentration is one thing. Extraction is another.
There's a common assumption that if you add water to grape must, you've automatically made a weak wine. That's far too simplistic, especially when we're starting with fruit this concentrated.
What's already in the juice
Water-back immediately changes the concentration of sugars, acids, potassium, nitrogen and compounds already dissolved in the liquid. We measure that. But it doesn't tell us everything about what the finished wine will taste like.
At crush, this Tannat tasted like ripe blackberry preserves, with very deep color and noticeable structure already present. Those observations matter just as much as the sugar number.
What the skins still have to give
Think about tea. You don't know how strong the finished tea will be just from the amount of water in the cup. The leaves, temperature, steeping time and extraction all matter.
Wine is more complex, but the same distinction helps: skins and seeds contain pigment, tannins and other constituents that enter the wine over time. Fermentation, alcohol, temperature, skin contact and punch-downs all influence how much is extracted.
Adding water does lower the initial concentration of substances already dissolved. But that does not automatically mean the finished wine will be thin or flavorless. We're working with unusually concentrated, richly flavored fruit and a large reservoir of extractable material in the skins. Extraction has limits, and too much can make Tannat harsh—so the goal is balance, not simply maximum extraction.
Complete ETS Analysis: what each result means
These are the actual pre-adjustment results reported for the Napa Tannat juice sample analyzed October 8, 2026. They are a starting snapshot, not a prediction of what the wine will measure after dilution, acid addition, fermentation, or malolactic fermentation.
| Analyte | Measured value |
|---|---|
| Brix | 33.6° |
| Glucose + fructose | 366 g/L |
| pH | 3.75 |
| Titratable acidity (TA) | 4.5 g/L |
| Potassium | 1,750 mg/L |
| Yeast-assimilable nitrogen (YAN) | 96 mg N/L |
| L-malic acid | 2.00 g/L |
| Tartaric acid | 4.5 g/L |
| Volatile acidity (acetic acid) | 0.24 g/L |
| Ammonia | 32 mg/L |
| Alpha-amino compounds (as N) | 70 mg/L |
View the original redacted ETS report
Brix & sugar: big potential, big decisions
33.6° Brix and 366 g/L glucose + fructose indicate unusually high sugar. Fermenting that concentration fully dry would demand far more alcohol tolerance than most yeast strains can practically deliver. Water-back is one route to a manageable dry red; retaining sugar is another stylistic choice.
pH & TA: measure both
pH 3.75 and TA 4.5 g/L indicate the need to consider freshness, microbial control, SO₂ effectiveness, and balance. pH is not interchangeable with TA. Acid adjustments should be made in stages and followed by new measurements and tasting.
Potassium: the buffering story
At 1,750 mg/L, potassium deserves attention. It participates in tartaric-acid buffering and potassium-bitartrate precipitation, which means a calculated acid addition may not produce the predicted pH movement. Dilution lowers potassium concentration, but the actual pH response still needs to be verified by remeasurement after the addition.
YAN: plan nutrition early
96 mg N/L YAN is low for a demanding, high-sugar fermentation. Choose an appropriate yeast, consider a balanced nutrient program, and make additions on the yeast's schedule rather than adding a large late dose. For the 25° Brix water-back example, expected YAN concentration falls to approximately 71 mg N/L. This is a serious nutrient-planning issue; the kit’s 5 g Fermaid O alone should not be assumed sufficient for medium-nitrogen-demand yeast.
Malic & tartaric acids
The 2.00 g/L malic acid result is relevant to any malolactic fermentation (MLF) plan. The 4.5 g/L tartaric acid measurement helps contextualize the starting acid system, but neither value alone tells you how many grams of tartaric acid to add.
VA, ammonia & amino compounds
0.24 g/L volatile acidity is a baseline acetic-acid measurement, not proof that the finished wine will be stable. 32 mg/L ammonia and 70 mg/L alpha-amino N help characterize the nitrogen pool; the separate YAN result should guide fermentation-nutrition planning.
Everything in the ETS table is a laboratory result. Alcohol potential, water-back volume, projected pH changes, residual sugar and bottled yield elsewhere in this guide are estimates based on explicit assumptions. Always remeasure your own batch.
Water-back, nutrients & extra bottles
This calculator estimates the prepared acidulated water to add, how dilution affects YAN concentration, and how many extra 750 mL bottles might result. Enter the actual juice recovery and measurements for your must—don't treat the default assumptions as guaranteed.
Calculate the added water and acidulate it
Use clean, low-mineral, chlorine/chloramine-free water. The aqua figures show the water-back volume and 6 g/L tartaric for that water alone, using the same volume-based Brix formula as the main WGD calculator.
Don't leave out the separate pH one-shot
For the specific 2026 Tannat reference recipe (33.6 → 25° Brix, 70% liquid, pH 3.75 → 3.60), the main calculator also gives 16 g additional tartaric per pail as its balanced one-shot. That amount is included in the displayed combined total when your Brix/liquid-fraction settings match the reference. Both doses may be dissolved in the same prepared water. *If you change the Brix or juice assumptions, the pH estimate is not automatically recalculated: use the full WGD calculator for a new balanced one-shot. Actual blended pH must be measured to verify the result.
Nutrition & yield estimates
Assumptions: 3.5 gal juice per pail, 75% of water reaching the bottle and the same volume-based Brix approximation as our main WGD calculator. These are estimates.
Water matters, but it does not need to be complicated. Plain distilled water with no minerals added is the easiest choice. Unsure what to buy or whether your tap/RO water works? See the water guide →
About the added bottles
It's a bonus, not a guarantee. Real yields depend on pressing, skins, lees, racking, losses and when you stop extracting. The model assumes a percentage of the water makes it into the bottle.
About flavor and extraction
The added water changes concentrations in the starting liquid, but the finished wine develops as pigment, tannin and flavors are extracted from the skins. Water volume alone cannot predict final character.
Choosing water for your adjustment.
For most people, the simple answer is easy: plain distilled water with no minerals added. If you are using tap, RO, spring, filtered or another source, the details below explain what to check.
Unsure what kind of water to use? Open the full water guide
For water-back, use water that is safe to drink, low in minerals, low in alkalinity, chlorine-free and chloramine-free. Do not assume that any bottled water, or anything that has passed through a filter, meets those requirements.
What to buy
The simplest choice: a sealed jug of plain distilled water sold for drinking or food use, with no minerals added. Examples of the exact product type:
- Great Value Distilled Water, 1 gallon — Walmart.
- Good & Gather Distilled Water, 1 gallon — Target.
Read the actual jug, not just the brand name. These are examples of the product type, not endorsements of every water those brands sell.
Reverse-osmosis (RO) water can also work when the finished water is suitable for drinking, low-mineral and chlorine-/chloramine-free, with no minerals added back.
What not to grab by mistake
Skip mineral water, alkaline water, electrolyte water, and water labeled “minerals added for taste” for this recipe. Spring water is not our default; its mineral content and alkalinity need checking first.
“Purified” does not mean “no added minerals.” Check the ingredients for added mineral salts. Even some distilled waters have minerals added back for taste.
Letting tap water sit overnight does not reliably remove chloramine. Do not rely on a quick boil or an unspecified pitcher/refrigerator filter, either. Use a verified treatment or buy suitable water.
Using city, well or filtered water? Check this first
Ask your local water utility: “Are you using chlorine or chloramine right now? Can you send the current water-quality report, plus hardness, total alkalinity and total dissolved solids (TDS)?” Treatment can change seasonally.
Check minerals and disinfectants separately. Water pH alone does not tell you its alkalinity or buffering capacity, and a low TDS reading does not prove chlorine or chloramine is absent.
Match the treatment to the source. A filter's chlorine-reduction claim is not automatically a chloramine-reduction claim. A water softener is not a substitute for demineralization, and some RO systems deliberately add minerals back after treatment.
Well water still needs checking. Confirm that it is safe to drink and check minerals and alkalinity. When you cannot establish the water quality, use the plain distilled-water option above.
For yeast rehydration, follow the exact yeast/Go-Ferm product protocol using a separate portion of clean, chlorine- and chloramine-free water. Never use the tartaric-acid water-back solution to rehydrate yeast.
Why these checks? Alkalinity can neutralize added acid, while chlorine/chloramine can create fermentation and taint risks. See the water references in Sources & methodology.
Three wines. One extraordinary Tannat.
The fruit gives us options. Water-back isn't only for a dry wine: even sweet and Port-style wines can benefit from a smaller addition of prepared acidulated water to balance the finished sugar. The point is to choose a style deliberately rather than assume the original Brix dictates the outcome.
Build the wine you want—not just the wine the Brix gives you.
Dry Rutherford Tannat
For a conventional dry red, the working example is 25° Brix. With approximately 3.5 gallons of liquid per 5-gallon must pail, our Wine Grapes Direct calculator estimates 1.20 gallons of low-mineral, chlorine/chloramine-free water to move from 33.6° to 25°. It then recommends 27 g tartaric for that water (6 g/L), plus a separate 16 g balanced one-shot pH addition to aim from the initial 3.75 pH toward 3.60. That's 43 g total tartaric, included in your Tannat kit for this one-pail recipe. Dissolve it into the same 1.20 gallons of water before blending it into the must. This is an estimated starting recipe, not a guaranteed pH measurement. For the beginner route, add the full reference one-shot to the whole pail, mix thoroughly, check after about 1 hour for an early reading, and use a later or next-day reading for fine correction when practical—especially given this must's high potassium.
Why water-back can work here: we're starting with extremely ripe juice and a substantial reserve of color and tannin in the skins. Extraction during fermentation contributes to the final wine. We are not relying on the volume of water alone to tell us how much flavor we'll have.
Yeast: RP15 or BDX are our familiar workhorses. Want a different expression? Use the interactive yeast selector below.
Use clean, low-mineral, chlorine/chloramine-free water, then dissolve the complete tartaric plan before adding it. The 27 g for the added water and the additional 16 g pH one-shot are both counted in the 43 g total. This estimate reflects the current 2026 Tannat lab sample and the selected pH target. If you measure and refine, never double-count acid already used.
Naturally Sweet Rutherford Tannat
Sweet wine isn't synonymous with leaving the grapes untouched. At 366 g/L glucose plus fructose, even a hypothetical fermentation to 16% ABV could leave around 94 g/L residual sugar without water-back; at 18% ABV, around 60 g/L. Either can taste quite sweet, depending on acidity, tannins and alcohol.
Suppose you'd prefer a finished wine in the vicinity of 45 g/L residual sugar. For our 3.5-gallon juice assumption, a rough scenario at 16% ABV calls for about 0.54 gallon of prepared acidulated water, while a theoretical 18% scenario calls for only about 0.15 gallon. These are sugar-balance illustrations, not promises that a yeast will reach or stop at those alcohol levels. Use the interactive sugar calculator below.
And remember: the water needs to be clean, chlorine/chloramine-free and acidulated with tartaric acid. This tartaric dose is to prepare the water (Stage 1). Once mixed, retest pH/TA and use our pH calculator for any additional adjustment (Stage 2). The first dose is already in the must—do not count it twice.
Do not rely on a yeast strain's advertised alcohol tolerance to stop at your desired residual sugar. Plan controlled fermentation arrest and microbial stabilization, verify actual sugar and alcohol, and use a validated finishing approach before bottling. Sweet wines with fermentable sugar can restart in the bottle.
Port-Style Tannat
For a Port-style wine, we let some sugar ferment and deliberately add grape spirit to raise alcohol while preserving sweetness. The original sugar concentration offers plenty to work with, but a small acidulated water addition may still improve the eventual sugar balance. Just as with the other styles, prepare the water with tartaric first, and separately recheck pH/TA after mixing before making any final pH correction.
For instance, start with 3.5 gallons of juice and 0.25 gallon of acidulated water. If fermentation reaches an assumed 13% ABV and we use a 77% ABV spirit to reach 20% final ABV, the simple mixing model indicates approximately 0.46 gallon of spirit and roughly 107 g/L residual sugar after fortification. Without added water, residual sugar would be higher under the same assumptions.
This is a bench-planning scenario, not a direct mixing instruction. Actual prefortification ABV, sugar, spirit strength, volume contraction, and sensory balance determine the final amount. Confirm the measurements and follow applicable rules for fortification.
Measured final alcohol, residual sugar, pH, sanitation and microbial stability still matter. Do not bottle a fortified wine simply because a calculation says 20% ABV.
The sugar & fortification planning calculator
Work backward from the wine you want. This model uses the ETS measurement of 366 g/L glucose + fructose and an approximate consumption of 17 g/L sugar per 1% alcohol. It's a planning model—not a prediction that any particular fermentation will achieve or stop at the numbers entered.
Acidulate the water first
Use clean, chlorine/chloramine-free water acidulated to a provisional 6 g/L tartaric starting concentration. This is only the water-acidulation dose. Determine any pH adjustment separately for your actual sweet or fortified wine.
STAGE 2: After mixing the acidulated water into the must, use the WGD pH calculator and measured pH/TA for any additional tartaric. Neither this sugar model nor its displayed water-acidulation grams includes final pH adjustment.
The model assumes sugar consumed at a fixed conversion rate for illustration. Finished results depend on fermentation and stability control.
Why 45 g/L matters
Forty-five grams per liter is one useful comparison point for a sweet wine—not a required target. Perceived sweetness depends on acidity, alcohol, tannin, temperature and texture.
With no water-back, the model gives about 94 g/L at a hypothetical 16% ABV or 60 g/L at 18% ABV. Small acidulated additions can change that outcome materially.
Why the Port-style number is different
Fortifying spirit increases alcohol and total volume, so it also affects residual sugar per liter. The tool applies both the water addition and a spirit blending calculation. Verify volume, ABV and sugar with testing and a bench trial.
Your yeast changes the character of the wine.
RP15 and BDX are our default recommendations for new winemakers, but there's no reason everyone needs to make the same Tannat. Filter by the style you want and what matters most to you. Then compare the strains and decide for yourself.
Enoferm RP15
Ripe fruit, spice and a full mid-palate.
- Published alcohol tolerance
- 17%
- Fermentation temperature
- 68–86°F / 20–30°C
- Nitrogen demand
- Medium
- Fermentation pace
- Moderate
Why we’d consider it:
Upside
Watch-outs
Alcohol tolerance and temperature are supplier specifications, not guaranteed results or an automatic fermentation stopping point. The fit, upside and watch-outs are our interpretation for this fruit. Selecting a strain here does not silently change the beginner recipe.
Read the manufacturer’s full specificationsCompare all 10 yeast strains and filter by wine style
Choose a card to bring its complete profile into view: alcohol tolerance, fermentation temperature, nutrient demand, pace, upside and watch-outs. The selected card stays highlighted below.
Yeasts shown: 10
Enoferm RP15
OUR WORKHORSEripe fruit · spice · full mid-palate
- Alcohol tolerance
- 17%
- Temperature
- 68–86°F
- Nitrogen demand
- Medium
An excellent candidate for bold, fruit-forward Tannat. A Rockpile Syrah isolate that builds rich mid-palate and ageable tannins.
Upside & watch-outs
Upside: Ripe berry and spice character, a broad mid-palate and color support. One of our familiar choices for a substantial dry red.
Watch-outs: Medium nitrogen demand matters in this lot. A 17% rating does not promise that an undiluted 33.6° Brix must will ferment dry.
Uvaferm BDX
OUR WORKHORSEjammy fruit · spice · classic structure
- Alcohol tolerance
- 16%
- Temperature
- 64–86°F
- Nitrogen demand
- Medium
A familiar Wine Grapes Direct workhorse. Reliable, moderately paced and well suited to structured Bordeaux-style reds.
Upside & watch-outs
Upside: Jammy and spicy varietal expression with good phenolic structure. A steady fermenter and another WGD workhorse.
Watch-outs: Its published 16% tolerance leaves less headroom than a high-tolerance strain. Keep nutrition and temperature under control.
Lalvin ICV D21
aromatic freshness · berry · balanced palate
- Alcohol tolerance
- 16%
- Temperature
- 59–82°F
- Nitrogen demand
- Low
Developed for mature, concentrated fruit; helps preserve a fresher impression in very ripe reds. Can produce VA if stressed.
Upside & watch-outs
Upside: Berry freshness and balanced mouthfeel can provide an interesting contrast to very ripe fruit. Published nitrogen demand is low.
Watch-outs: The supplier warns it can produce volatile acidity under stress. Low demand is not permission to skip nutrition.
Lalvin ICV D254
ripe plum · roundness · weight
- Alcohol tolerance
- 16%
- Temperature
- 54–82°F
- Nitrogen demand
- Medium
Emphasizes plush mouthfeel, red/black fruit and a full mid-palate. Temperature control is important with high alcohol.
Upside & watch-outs
Upside: Ripe plum and berry character with a round, full mid-palate and stable color.
Watch-outs: Temperature management becomes especially important at higher alcohol. Richness is a stylistic choice, not the only goal.
Lalvin BM4x4
jam · cherry liqueur · sweet spice
- Alcohol tolerance
- 16%
- Temperature
- 64–82°F
- Nitrogen demand
- High
A Brunello-linked yeast blend for aromatic complexity and rounded tannins. Higher nutrient demand makes it less beginner-friendly here.
Upside & watch-outs
Upside: Aromatic complexity, polysaccharide release and rounded mouthfeel; an interesting Italian-inspired option.
Watch-outs: High nitrogen demand makes this a more demanding choice for the low-YAN Tannat. Do not copy the RP15/BDX nutrient quantities.
Lalvin CLOS
berry · mid-palate · ageable tannin
- Alcohol tolerance
- 17%
- Temperature
- 55–90°F
- Nitrogen demand
- Medium
A structured-red option developed from a Priorat isolate, with low H2S production and good color/tannin intensity.
Upside & watch-outs
Upside: Berry fruit, mid-palate weight and ageable tannins, with a supplier-reported reliable fermentation profile.
Watch-outs: Can start slowly in cold must and move quickly when warmer. Plan monitoring and cap management around that pace.
Lalvin T73
ripe berries · plums · fruit-forward
- Alcohol tolerance
- 16%
- Temperature
- 65–90°F
- Nitrogen demand
- Low
Selected for red wines from warm growing conditions. Extremely low nitrogen demand makes it interesting for this must.
Upside & watch-outs
Upside: Ripe berries and plum with low nitrogen demand; selected for warm-climate red-wine expression.
Watch-outs: Its 16% rating is not a reliable stop switch for sweet wine. A low-demand strain still needs adequate nutrients.
Uvaferm 43
red berries · color · fructose fermentation
- Alcohol tolerance
- 18%
- Temperature
- 55–95°F
- Nitrogen demand
- Low
Fructophilic yeast well suited to high-maturity grapes and challenging residual fructose conditions.
Upside & watch-outs
Upside: Fructose use and high-sugar fermentation resilience, alongside red-berry character and good tannin intensity.
Watch-outs: A vigorous strain can move past a desired sweetness quickly. An 18% rating is not a guarantee of dryness in the original must.
Lalvin EC-1118
neutral profile · fast · reliable
- Alcohol tolerance
- 18%
- Temperature
- 50–86°F
- Nitrogen demand
- Low
Useful for challenging fermentation and late-harvest conditions. When YAN is low it may generate SO₂ that complicates MLF.
Upside & watch-outs
Upside: Robust, low-foaming fermentation with compact lees. Useful when fermentation reliability is the priority.
Watch-outs: Under nutrient stress it can produce SO2 that inhibits MLF. Fast fermentation also calls for close monitoring when retaining sweetness.
Enoferm Syrah
plum · violet · peppery spice
- Alcohol tolerance
- 16%
- Temperature
- 59–90°F
- Nitrogen demand
- Medium
A Rhône-inspired alternative for a more savory, floral and spicy Tannat expression.
Upside & watch-outs
Upside: Berry, plum, violet and peppery-spice possibilities, with mouthfeel and color support.
Watch-outs: Medium nitrogen demand and a 16% alcohol rating need to be respected. Aromas depend on the grapes; this does not make Tannat taste like Syrah.
The advertised alcohol tolerance is a performance limit under suitable conditions, not a reliable way to stop a sweet fermentation. Yeast strain influences flavor and texture but does not replace fruit quality, fermentation temperature, oxygen management, and nutrient planning. Manufacturer specifications are linked on every card. We don't claim to have personally trialed every strain listed here.
What to use, how much, and when.
Use the standard 5 g Fermaid O and 5 g Opti-Red portions. For this unusually low-YAN Tannat, DAP is the separate nitrogen supplement. Go-Ferm Sterol Flash handles yeast rehydration; Opti-Red handles color and mouthfeel. Those are different jobs.
Quantities below are for one 5-gallon must pail, estimated 3.5 gallons of juice, water-backed from 33.6 to 25° Brix. The resulting liquid is about 4.70 gallons (17.8 L). This is not a recipe for every yeast or every sweet/fortified batch.
Yeast: RP15 or BDX
- In the kit
- 5 g
- This one-pail example
- 5 g
Choose one strain. Rehydrate with Sterol Flash, then inoculate the prepared must.
Go-Ferm Sterol Flash
- In the kit
- 5 g supplied
- When
- Yeast rehydration
Use the supplied 5 g pouch with the selected yeast and follow the current Sterol Flash instructions. For a 5 g pouch, the 10× water ratio is about 50 mL of clean water at or above 59°F (15°C). Keep DAP out of the rehydration water.
Fermaid O
- In the kit
- 5 g
- This one-pail example
- 5 g total
Use the supplied portion. Split into two 2.5 g feeds, after a 2–3° Brix drop and at one-third sugar depletion.
Opti-Red
- In the kit
- 5 g
- This one-pail example
- 5 g
Use the supplied portion near inoculation for color and mouthfeel support. It is not the nitrogen supplement.
FT Rouge
- In the kit
- 7 g
- This one-pail dry-red example
- 7 g
For the recommended dry-red route, add the 7 g portion near the start of fermentation for early tannin and color support. If you intentionally choose a different extraction or fermentation-oak program, adjust rather than automatically stacking every tannin source.
Tartaric acid
- In your Tannat kit
- 43 g supplied
- This one-pail dry-red recipe
- Use the included 43 g pouch
The pouch covers about 27 g for the added water plus the 16 g modeled pH adjustment. Dissolve all 43 g into the same 1.20 gallons of low-mineral, chlorine/chloramine-free water. Do not add another 27 g or 16 g on top of the pouch.
This is the starting plan for the stated one-pail dry-red recipe, not a guaranteed final pH. Other batch sizes or sweet/fortified styles need their own calculation; do not automatically use the full pouch for a different plan.
DAP: additional nitrogen
- In the kit
- Not included; source separately
- This one-pail example
- 10 g total
For the stated 25° Brix, low-YAN RP15/BDX batch only: two 5 g feeds with Fermaid O. DAP supplements organic nutrition; it does not replace its other components.
Potassium metabisulfite / SO₂
- In the kit
- Not included
- This one-pail example
- Based on stage and analysis
Manage free SO₂ using measured pH and the wine’s condition. A one-shot acid addition is not a microbiological-stability test.
Malolactic culture
- In the kit
- Not included
- This one-pail example
- Style-dependent
Choose your MLF strategy, then confirm completion before finishing a dry red. Sweet and fortified styles need their own stability plans.
Grape spirit
- In the kit
- Not included
- This one-pail example
- Fortified style only
Calculate from measured wine alcohol, spirit strength, actual volume and the target blend. The dry-red nutrient recipe is not automatically the right fortified-wine recipe.
Technical dosing notes for the nutrient plan
Sterol Flash: Scott Laboratories publishes 30 g/hL Sterol Flash with 25 g/hL active dried yeast, a 1.2:1 nutrient-to-yeast ratio. The WGD kit portion is 5 g; follow the current product instructions rather than older hot-water Go-Ferm directions.
Fermaid O + DAP: the 5 g Fermaid O + 10 g DAP plan in this guide is a lot-specific working program for the 25° Brix dry-red route after water-back, not a universal recipe for every yeast or wine style. Add the two feeds early as shown above and do not make routine late DAP catch-up additions.
- Use the supplied portions
- 5 g yeast, 5 g Sterol Flash, 5 g Fermaid O, 5 g Opti-Red, up to 7 g FT Rouge if wanted, and 43 g tartaric acid for this Tannat recipe.
- The tartaric is included
- Your Tannat kit supplies the 43 g pouch for the reference water-and-pH plan: about 27 g for the water plus 16 g for the modeled pH adjustment. For this recipe, no separate tartaric purchase is needed. Dissolve it in the prepared water once; do not double-count it.
- Source separately
- 10 g winemaking-grade DAP for this specific RP15/BDX example. We do not currently stock DAP for our kits; we are considering adding it.
- Use the right instructions
- Follow the Sterol Flash pouch, not the original Go-Ferm instructions. The final pH and fermentation outcome remain batch-dependent.
A nitrogen plan, not a gram-for-gram swap.
The starting 96 mg/L YAN becomes about 71 mg/L after this water-back. In 17.8 L, 5 g Fermaid O contributes about 11 mg/L measurable YAN, or about 45 mg/L in Scott’s current nutritional-equivalent model. Ten grams of DAP contributes about 118 mg/L YAN.
That is approximately 200 mg/L on a measurable-nitrogen basis, or 234 mg/L using the current Fermaid O equivalent. These are different calculations; they must not be added together. The planning reference for a medium-demand yeast at 25° Brix is about 230 mg/L, interpolated between Scott’s 24° and 26° examples.
This mixed program is our batch-specific interpretation, not a manufacturer-tested recipe for these grapes. Fermaid O also supplies amino acids and micronutrients that DAP does not. Neither the numerical target nor extra DAP guarantees a healthy fermentation. Fermaid O data · DAP guidance · Nutrition planner
Make the timing obvious.
- Rehydration
- Sterol Flash + yeast only, following the Flash procedure. No DAP here.
- First feed
- After a 2–3° Brix drop: 2.5 g Fermaid O + 5 g DAP.
- Second feed
- At about one-third sugar depletion: 2.5 g Fermaid O + 5 g DAP.
- After that point
- Do not add late nitrogen automatically. Troubleshoot a slow or stressed fermentation rather than repeating the early-feed schedule.
At a 25° Brix starting point, a hydrometer reading near 16–17° is a practical one-third-depletion marker, not a laboratory sugar assay. Alcohol affects readings; follow the nutrient supplier’s timing guidance.
MLF, stabilization and finishing: choose deliberately
Decisions made after primary fermentation matter just as much as Brix at the start. Your preferred wine style should determine the malolactic fermentation and microbial stability plan.
Dry red
MLF may be appropriate to soften acidity and create a stable red-wine profile. Confirm completion analytically rather than assuming it happened. Track pH and manage sulfite, oxygen and microbial risk accordingly.
Naturally sweet red
MLF might be a deliberate choice, but residual sugar and malic acid can complicate microbial stability. Plan the sequence of fermentation, MLF (if used), stabilization, filtration, and bottling rather than trying to fix sweetness-related problems at the end.
Port-style
Fortification changes the microbial environment, but stability still depends on measured alcohol, residual sugar, pH and sound cellar practices. Avoid assuming alcohol alone makes every fortified wine shelf-stable.
Different styles, different finishing plans
Dry red: Decide whether to complete MLF; confirm it analytically, then manage sulfur dioxide, oxygen and stability.
Naturally sweet: Preserving sugar means reliable fermentation control, microbial stabilization and usually filtration decisions.
Port-style: Verify alcohol and sugar after fortification; don't assume a higher ABV eliminates all microbial risk.
Test the wine you actually made: alcohol, pH, TA, residual glucose/fructose, free/total SO₂ as appropriate, and MLF status where relevant. Sweet and fortified wines require a credible microbial stability plan before bottling.
For the dry red, add flavor oak after MLF and the heavy rack.
Our standard red-grape program uses FT Rouge during fermentation for early tannin/color support. When you follow that program, our normal plan is to save the flavor oak for the cleaner wine: finish and verify MLF, rack off the heavy lees and particulate, then add oak to the wine you actually intend to age. That keeps more of the oak contribution in the finished wine instead of sending it out with a heavy post-MLF rack.
One important exception: if you intentionally skip FT Rouge or another fermentation tannin, fermentation oak becomes a separate tool. OSG’s Cabernet guide, for example, includes heavy-toast French or American small chips at 2 g/L during fermentation. Do not automatically stack a fermentation-oak program on top of the full FT Rouge plan.
A practical French-oak starting point: based on our experience, about 20 g of medium-to-heavy-toast French oak cubes per roughly 4 gallons of finished wine is a dependable place to start for the aging period. Taste the wine at about three months even at this dose: it may be right where you want it, it may benefit from more contact time, or you may decide to add another measured amount of oak. If you start above 20 g, taste earlier and more often so the oak does not run past the wine.
Dry Tannat already brings enormous structure. The 20 g French-cube reference is a sensible first aging layer, and Hungarian is another good classic-style option. American should start lower because its oak character can be more overt. The exact OSG dose rates below come from OSG’s Cabernet guidance and are included as format-and-dose references—not as a Tannat-specific prescription.
Think dose + format + time. Chips extract fastest, cubes build more gradually, and a large stave can seem quiet early while still carrying a lot of wood that keeps extracting. A slow start does not mean a stave has a low final ceiling.
French oak
For medium through heavy toast, our practical cube starting point is 20 g per ~4 gallons. For chips, start around 15 g per ~4 gallons and taste sooner. French oak is the classic lane for structure, toast and spice without forcing the oak to the front.
Hungarian oak
We treat Hungarian oak similarly to French for starting dose: about 20 g cubes or 15 g chips per ~4 gallons. It often lands near French oak stylistically but can show more vanilla, spice and caramel-like character. Toast and supplier still matter.
American oak
American oak commonly shows more obvious vanilla, coconut and sweet/spicy oak character, so we start lower: about 15 g cubes or 12 g chips per ~4 gallons, then taste before adding more. These are practical starting points, not manufacturer specifications.
Pick the oak you can actually get, scale it to your finished wine, and know when to taste.
Enter the finished wine volume after MLF and the post-MLF rack. The general French/Hungarian/American choices are practical starting points for home winemakers. The OSG choices marked as Cabernet references use the published rates from Oak Solutions Group’s Cabernet guide.
Tannat note: OSG’s exact product rates in this selector are Cabernet recommendations used here as reference points. The general French/Hungarian/American entries are practical home-winemaker starting points, not OSG Tannat prescriptions.
Based on our experience, 20 g of medium-to-heavy-toast French oak cubes per about 4 gallons is a dependable aging starting point. Taste around three months even at this dose. If the wine wants more oak, continue contact or add another measured amount; if you start above 20 g, taste earlier and more often.
For staves: the calculator shows the OSG material-rate equivalent in grams. A physical stave is normally sold by piece/configuration, so use OSG’s official calculator or product instructions to convert that program into the actual stave system you are buying. Taste on schedule and pull the stave when the oak is right.
Browse the wider Oak Solutions Group ēvOAK catalog
French, American & dark roast
ēvOAK Classic French Oak and Classic American Oak are the straightforward oak-family options. OSG lists French Oak and American Oak in chips, while its Classic tank-stave products are also available in cube, CUBEtube, infusion-stave, fan-system and Oak Flavoring Stix configurations. Premium Dark Roasted is listed in chips.
Five precision-toasted chip programs
NG.567F, NG.466F, NG.263F, NG.455A and NG.354A. OSG positions this series around combinations of intensity, mouthfeel and structure using French and American oak.
Flavor-forward finishing tools
High Spice, High Toast, High Mocha, High Vanilla, PURE2 Vanilla and High Caramel. OSG lists High Extract products in chips and stave-based formats; many stave products are also available as cubes and other configurations.
Longer-term aging profiles
33° Mendoza, 42° Rioja, 44° Bordeaux, 45° Rhône and 46° Burgundy. OSG describes Latitude as a long-term-aging series with gradual evolution; its published material notes a typical minimum maturation window of about 4–6 months.
Cuvée Nº 1 through Nº 5
Cuvée Nº 1, Nº 2, Nº 3, Nº 4 and Nº 5. The full Cuvée family is listed in stave/cube-style configurations; Nº 1 and Nº 2 are also listed in OSG's chip catalog.
Savory, Intense, Fruit, Balanced & XT4
Precision Fire Toast Savory, Intense, Fruit and Balanced are offered in stave/cube-style configurations. XT4 is listed as a chip product and appears in OSG's Cabernet finishing blend with High Mocha.
Also in OSG's broader catalog: the High Proof line (Charred Barrel, Sweet Shoppe, Rickhouse and Spice Rack) is aimed at high-proof/spirits applications, so we list it for completeness but do not build it into this wine-aging calculator. OSG also sells oak powder and trū/tan tannins; those are different tools from the post-MLF aging program here.
Catalog availability and configuration can change. See OSG's current configuration catalog ↗
French oak is usually the most classic/subtle lane, Hungarian often lands close to French with plenty of vanilla/spice character, and American oak is often more overtly vanilla/coconut/sweet-spice driven. Toast can move any of them toward caramel, coffee, smoke or dark chocolate. That is why the calculator gives you a starting dose and a tasting checkpoint, not a promise of a fixed flavor result.
Your notes. Your videos. Your Tannat.
Tell us what you’re making and how it’s going. We review submissions before choosing what to feature. Your email stays private, and publication is subject to your permission.
Share your winemaking notes
Start with measurements and first impressions, then tell the story in your own words. Updates during fermentation, aging and tasting are welcome.
Go to the notes form ↓Share an update now, and another one later.
Making a video about this Tannat?
Send it our way so we can consider featuring it right here. Share a viewable video link and tell us what we’re seeing.
Go to the video form ↓Send a viewable link through our form.
Share your Tannat story
What did you think of the juice? How are you making your wine? Whether this is your first batch or your fiftieth, we'd love to see what you do with our 2026 Rutherford Tannat. Tell us what you know, skip what you don't, and come back with updates.
Share your starting chemistry, first impressions, yeast choices, and anything interesting that's happened along the way. Measurements are optional.
No account needed. Fill this out, then open the prepared email draft and send it from your usual email app.
- 1. Your batch
- 2. The details
- 3. Review & email
2026 Rutherford Tannat · Grape Must
McGah Family Heritage Vineyard · Rutherford AVA · 5-gallon must pails. See the current listing for availability, ETS report imagery and fulfillment updates.
Sources & calculation assumptions
Calculation method: This guide uses the same simple Brix water-back equation as our main WGD tool: added water = projected juice gallons × (initial Brix / target Brix − 1). It neglects density differences, so the final Brix should be measured. Water acidulation is calculated at 6 g/L. The 16 g pH balanced one-shot is the main calculator's separate illustrative estimate for the stated 3.75 → 3.60 one-pail scenario. Combined 43 g is not a guaranteed post-blending pH or stability result.
Primary data: ETS Laboratories, sample labeled “Juice Sample Lodi 10/8/2026, Napa Tannat,” analyzed October 8, 2026. Reported measurements apply to the submitted sample. Vineyard: Heritage Vineyard, Block 3C, Tannat selection 1.1, planted 2022. Harvest impressions reflect what we tasted during processing. Independent educational reading:
- MoreWine — Water-back using water pre-acidulated to 6 g/L tartaric
- Scott Laboratories — 2026 fermentation nutrition planning
- Scott Laboratories — GO-FERM STEROL FLASH rehydration protocol (different from regular Go-Ferm)
- Scott Laboratories — Fermaid O dose and measurable YAN
- Scott Laboratories — DAP use for severely low-YAN must (with complex nutrients)
- Lallemand — Opti-Red use and dosing
- Castelli Romani — Cannellino di Frascati tradition
- Australian Wine Research Institute — water additions and chlorine/chloramine removal
- USGS — alkalinity and water buffering
- CDC — chlorine and chloramine in drinking water
- EPA — finding your local drinking-water quality report
- Scott Laboratories — current Fermaid O dosing and nitrogen equivalents
- Scott Laboratories — DAP: use with complex nutrients
- Consorzio Tutela Vini Montefalco - Sagrantino and the traditional passito
- Arnaldo Caprai - Sagrantino, tannin structure and aging
Educational information only. Outcomes depend on the actual must, representative measurements, yeast selection, sanitation, fermentation management and style-specific trials where appropriate. This article is not a guarantee of wine quality, bottle yield or microbiological stability.