What do I do if my yeast stops working before all the sugar is used up?
Make sure that your mix has not actually finished by checking the Specific Gravity(SG) with a hydrometer. The SG should be around 990.
If the SG is higher than 990 and all sign of fermentation has stopped, first try restarting the mix. This can often be achieved by stirring the yeast that has settled on the bottom of the fermenter back into the liquid and also ensuring that the mix is at the correct temperature for the yeast strain used.
If the SG is below 1005 and fermentation has stopped and you can not restart by the method above, then distill as normal but use some Distilling Conditioner. This will ensure that unfermented sugar in the mix does not cause frothing during distilling. You will also get a slightly lower yield of distilate.
If the SG is higher than 1005 but when the alcohol content in the stuck batch is lesss than 9%, try adding some bayanus yeast (Vintners Harvest SN9 or CL23 strains). These yeasts are particularly good at starting in the presence of alcohol and are used in Champagne making for the secondary fermentation in the bottle. Most other yeast varieties will be destroyed by being added to a mix which contains alcohol because they need to build up a resistance to alcohol during the normal process of fermentation.
Do not add more Turbo or Nutrients as excess nutrients at this stage will result in problems distilling and may actually make the mix more difficult to ferment.
The best method to get the yeast going again is:
- In a 1 litre jug, rehydrate your Bayanus yeast in 100 mls of water at 30o C with 1 teaspoon of dextrose.
- When this is fermenting, add 100 mls of stuck mix.
- When this is fermenting add a further 200 mls of stuck ferment.
- When this is fermenting add a further 400 mls of stuck mix.
- When this is fermenting add half to the stuck mix and top up with the same.
- Continue until fermentation has restarted.
When the alcohol content in the stuck batch is over 9% or when the method above does not get you going again, do not dispair.
- Start a fresh batch with a new batch of Turbo yeast & 6 or 8kg of sugar in another fermenter.
- Let it ferment for 2 days
- Transfer half of the new batch to a third fermenter
- Transfer half of the stuck batch to one of the half new batches
- Transfer the remaining stuck batch to the other half new batch
- Allow both batches to ferment through normally & clear & distill as you would usually do it.