Stuck Ferment: Twelve Grams Left and a Friday Deadline

What the numbers exclude first

• 11.6% alcohol plus 12 g/L RS (≈0.7% potential) lands the wine around 12.3% total. That is below the tolerance of essentially every commercial strain, so alcohol toxicity is not the primary cause.
• VA at 0.41 g/L is slightly elevated but not a spoilage crisis; no film, no volatile sulfur - this is a stalled ferment, not a contaminated one.
• 4 × 10^5 cfu/mL is a healthy viable population. The yeast is alive; it is not working.

Ranking

1. Nutrient depletion. YAN of 95 mg/L is low for a white must (target 150–250). Once the yeast passes roughly two-thirds sugar depletion it cannot assimilate nitrogen efficiently anyway, so the tank ran out of usable nitrogen exactly when demand peaked.
2. Temperature shock. 30 hours at 11 °C does not kill Saccharomyces, but it arrests it, and a chilled, nutrient-poor, increasingly alcoholic medium is very hard to restart.
3. Osmotic stress at 24.8 °Brix early on - a contributor, now past.
4. Alcohol - effectively ruled out.

The dangerous move is pitching fresh yeast straight into that barrel. Freshly rehydrated yeast dropped into a 11.6% alcoholic, cold, nitrogen-poor wine with no acclimatisation will largely die and add off-flavours and biomass. Adding DAP at this stage is also the wrong tool: late DAP is poorly assimilated, leaves residual nitrogen for spoilage organisms, and does not solve a temperature problem. Warming is the only sound instinct - but it must be gradual, not a jump.

Stage 1 - Thermal and mechanical (Days 0–3)

• Warm the barrel room to 18–20 °C over 24–36 hours. A fast rise causes its own shock; target roughly 1–2 °C per hour at most.
• Rouse each barrel twice daily (rolling or a gentle gas rouse) to keep yeast in suspension and release CO2.
• Go/no-go: gravity every 12 hours. Any sustained drop in RS (a few g/L over 48–72 h) means the ferment is moving - hold the course.

Stage 2 - Nutrition and surface area (Days 3–5, only if Stage 1 fails)

• Add yeast hulls (roughly 20–30 g/hL) to adsorb inhibitory medium-chain fatty acids and provide surface area, plus an organic (autolysate-type) nutrient rather than straight DAP.
• Go/no-go: another 48–72 hours of gravity checks.

Stage 3 - Restart culture (Day 5+)

• Rehydrate a restart-designated strain with a rehydration nutrient, then acclimatise by adding fractions of the stuck wine (roughly 10% of the starter volume at a time) over several hours, keeping the temperature differential under about 10 °C, before inoculating.

Do not: add SO2 during the restart, splash-rack into oxygen, or blend the lot into a healthy tank to "dilute" the problem - you would just stall the healthy wine too.

1. Own the style. Chill, rack clean, sterile-filter to 0.45 µm to stop any further activity, and sell it as an off-dry Chardonnay. Commercially this is sometimes the best outcome - 12 g/L with high acid is a legitimate food wine - but it breaks the single-lot plan and the label must declare residual sugar honestly. Check the appellation's rules: many Old World PDOs restrict residual sugar or require specific labelling terms.
2. Blend away. Fold the lot into a larger dry component at a ratio that keeps the final RS under your target and any legal threshold. Cost: you lose 4.5 tonnes of identity, and the blend must be re-tasted and re-papered.
3. Referment in bottle (méthode traditionnelle). High risk with a stressed population and unknown nutrient status; only viable with a fresh, acclimatised culture and rigorous pressure monitoring.
4. Distil or sell in bulk. Recovers a fraction of value; often requires a permit and destroys the premium positioning.
5. Do not bottle it still and unfiltered. Residual yeast plus 12 g/L sugar in a warm cellar is a refermentation waiting to happen; you would be shipping glass grenades and risking a recall.

Whichever route, record the intervention history. If this lot carries a vineyard designation, the buyer needs to know before the label is designed.