I've got several demijohns on the go, and some have got stuck.
They've been going for a few weeks now, and seemed to stop as soon a I racked them.
Anyway, before I got trying different things, I just have one question. I feel like I should effectively start from scratch again by killing everything off. Can I do this successfully with a couple of crushed campden tablets for 24hrs, or should I boil the must. I've got a lot of wine, so the campden tablets are my preferred option, or some sodium metabisulphate powder I have.
Is this even necessary, and if so why not?
Cheers
James
Wine fermentation stuck. Boil or campden tablets?
Re: Wine fermentation stuck. Boil or campden tablets?
Before your questions can be answered, James, I need an answer from you ...
If the wines were still fermenting, why did you rack them? I assume that if, as you say, they'd been going for a few weeks (how many weeks, exactly?) then we're not talking about getting the liquid off the solids after initial fermentation on the must.
Mike
If the wines were still fermenting, why did you rack them? I assume that if, as you say, they'd been going for a few weeks (how many weeks, exactly?) then we're not talking about getting the liquid off the solids after initial fermentation on the must.
Mike
The secret of life is to aim below the head (With thanks to MMM)
Re: Wine fermentation stuck. Boil or campden tablets?
About 5 weeks before I racked them. Everyone as you know, seems to have a different opinion on how to make wine. I did it when I felt sufficient sediment had settled at the bottom.
The wine group I normally go to, racks it much sooner and they have no problems. Are you suggesting you don't rack them until they've stopped fermenting?
Thanks
The wine group I normally go to, racks it much sooner and they have no problems. Are you suggesting you don't rack them until they've stopped fermenting?
Thanks
Re: Wine fermentation stuck. Boil or campden tablets?
Different opinions - oh boy, yes 
After 5 weeks fermentation, I'd say that it was just about over anyway. Most of the sugar would have been used by that time and the alcohol content would be beginning to weaken the yeast. In fact, the yeast may already have gone into retirement and the fermentation may have been carrying on because of the enzymes the yeast had left behind - which is normal.
If you ferment on the pulp rather than using juice as a starting point, then you're going to have to remove the wine from the fruit pulp at some point. That's normally done within a week of the start of fermentation (and even a week would be quite some time). This, strictly speaking, is counted as straining rather than racking. I don't think this is what you mean. After that point, I would consider it normal to let things alone until the fermentation has stopped before even thinking about racking. The deposit at the bottom of the demijohn will consist of a bit of fruit pulp which got through the straining operation, but mostly dead and inactive yeast cells. This will deteriorate if not removed, but that takes a long time (I've accidentally left finished wine on its deposit for a month with no off-tastes developing, though I wouldn't recommend that practice).
When you rack, you introduce oxygen into the wine. Yeast, in the presence of oxygen, goes into its aerobic phase - instead of producing alcohol, it tries to divide. You want this to happen when you start a wine off, but if you do it later while the yeast is still active, all that's going to happen is that a delay in the fermentation time will be introduced - until the oxygen has all been used up, at which point the yeast goes into its anaerobic phase and starts to produce alcohol again. In this case, the attempt at division may well have been the last straw for your yeast, and it went to the Great Enzyme in the Sky.
So I'd suggest that your fermentation is over (although, you never know, the little buggers might just recover again and drag everything along a little further if you wait long enough. For the odd half per cent of alcohol content you'd gain, I'd say it's hardly worthwhile waiting to find out). So - when the wine is clear is the time to rack (and should have been your first racking). This time, you're also going to introduce oxygen but, as there's no yeast to use it up, it will stay in solution. For small amounts of oxygen, this isn't a bad thing. For large amounts, it IS a bad thing unless you want a wine with a distinct sherry flavour. There are two ways around this - you can be extremely gentle in your racking, ensuring that the wine runs down the side of the demijohn rather than splashing down from on high, or you can use metabisulphite (one crushed tablet per gallon) to prevent the oxidation action. The metabisulphite also has the advantage of stunning any yeast cells which stand a chance of re-activating.
All in all, I wouldn't start anything over again - I think your wine is probably done to a turn. There's an easy way to find out - that's what your mouth is for
I'd be fascinated to know why your wine group thinks racking during fermentation should be necessary.
Mike
After 5 weeks fermentation, I'd say that it was just about over anyway. Most of the sugar would have been used by that time and the alcohol content would be beginning to weaken the yeast. In fact, the yeast may already have gone into retirement and the fermentation may have been carrying on because of the enzymes the yeast had left behind - which is normal.
If you ferment on the pulp rather than using juice as a starting point, then you're going to have to remove the wine from the fruit pulp at some point. That's normally done within a week of the start of fermentation (and even a week would be quite some time). This, strictly speaking, is counted as straining rather than racking. I don't think this is what you mean. After that point, I would consider it normal to let things alone until the fermentation has stopped before even thinking about racking. The deposit at the bottom of the demijohn will consist of a bit of fruit pulp which got through the straining operation, but mostly dead and inactive yeast cells. This will deteriorate if not removed, but that takes a long time (I've accidentally left finished wine on its deposit for a month with no off-tastes developing, though I wouldn't recommend that practice).
When you rack, you introduce oxygen into the wine. Yeast, in the presence of oxygen, goes into its aerobic phase - instead of producing alcohol, it tries to divide. You want this to happen when you start a wine off, but if you do it later while the yeast is still active, all that's going to happen is that a delay in the fermentation time will be introduced - until the oxygen has all been used up, at which point the yeast goes into its anaerobic phase and starts to produce alcohol again. In this case, the attempt at division may well have been the last straw for your yeast, and it went to the Great Enzyme in the Sky.
So I'd suggest that your fermentation is over (although, you never know, the little buggers might just recover again and drag everything along a little further if you wait long enough. For the odd half per cent of alcohol content you'd gain, I'd say it's hardly worthwhile waiting to find out). So - when the wine is clear is the time to rack (and should have been your first racking). This time, you're also going to introduce oxygen but, as there's no yeast to use it up, it will stay in solution. For small amounts of oxygen, this isn't a bad thing. For large amounts, it IS a bad thing unless you want a wine with a distinct sherry flavour. There are two ways around this - you can be extremely gentle in your racking, ensuring that the wine runs down the side of the demijohn rather than splashing down from on high, or you can use metabisulphite (one crushed tablet per gallon) to prevent the oxidation action. The metabisulphite also has the advantage of stunning any yeast cells which stand a chance of re-activating.
All in all, I wouldn't start anything over again - I think your wine is probably done to a turn. There's an easy way to find out - that's what your mouth is for
I'd be fascinated to know why your wine group thinks racking during fermentation should be necessary.
Mike
The secret of life is to aim below the head (With thanks to MMM)
Re: Wine fermentation stuck. Boil or campden tablets?
Hi Mike
Thanks for the response.
I'm unlikely to see them anytime soon, but I'll try and remember to ask them. From what I can remember, they said if anything's going to turn the wine bad it'll be at the top or the bottom i.e. the air gap, or the accumulated stuff at the bottom.
And I just dug up a recipe I found on the web which recommends racking after 10days in the demi john, then leave it alone until it's finished.
Anyway, as we said. Everyone's got an opinion.
I would say you're right. I checked the SG of my 7 demi johns and all were around 1000 which from what I've been told, indicates they're probably finished. One was as low as 990. All very dry. All started off with 3lbs of sugar.
The odd thing is, some of them don't taste at all alcoholic. And some have a slight fizz which concerns me. Bear in mind, I left them sitting there not fermenting for a few weeks in the demi john. I may have racked them once or twice, I forget now. Thus losing some wine, leaving a bigger air gap at the top, and introducing oxygen and I guess potentially bad bacteria.
Or could it just be CO2?
I guess my best bet now is couple of campden tablets crushed in each, then just leave and hope the fizz dissipates.
But there's still this question about the lack of alcohol when I tasted. Definitely tastes like a dry wine. But where did my sugar go?
I just remembered one last thing. The temperature has been getting steadily colder. We don't have an airing cupbaord anymore so they're at the top of a wardrobe. It's only just 18C, but at least it's constant.
Thanks for the response.
I'm unlikely to see them anytime soon, but I'll try and remember to ask them. From what I can remember, they said if anything's going to turn the wine bad it'll be at the top or the bottom i.e. the air gap, or the accumulated stuff at the bottom.
And I just dug up a recipe I found on the web which recommends racking after 10days in the demi john, then leave it alone until it's finished.
Anyway, as we said. Everyone's got an opinion.
I would say you're right. I checked the SG of my 7 demi johns and all were around 1000 which from what I've been told, indicates they're probably finished. One was as low as 990. All very dry. All started off with 3lbs of sugar.
The odd thing is, some of them don't taste at all alcoholic. And some have a slight fizz which concerns me. Bear in mind, I left them sitting there not fermenting for a few weeks in the demi john. I may have racked them once or twice, I forget now. Thus losing some wine, leaving a bigger air gap at the top, and introducing oxygen and I guess potentially bad bacteria.
Or could it just be CO2?
I guess my best bet now is couple of campden tablets crushed in each, then just leave and hope the fizz dissipates.
But there's still this question about the lack of alcohol when I tasted. Definitely tastes like a dry wine. But where did my sugar go?
I just remembered one last thing. The temperature has been getting steadily colder. We don't have an airing cupbaord anymore so they're at the top of a wardrobe. It's only just 18C, but at least it's constant.
Re: Wine fermentation stuck. Boil or campden tablets?
I'd be VERY surprised if any of them is low in alcohol. 3lbs of sugar gives you about 15% ABV even without taking into account any natural sugars from the fruit. In a good wine, you shouldn't be too conscious of alcohol anyway - at least not as far as the taste buds are concerned.
Don't be too concerned about the slight fizz. It could me one of quite a few things, none of them harmful, one of them possibly very beneficial, and it will dissipate anyway in time.
Don't leave growing air gaps as you rack - you should be topping up with water (makes very little difference to the wine). Leave only a small gap between the wine and the bottom of the airlock bung (you're OK to top up right now).
18 degrees C is fine for fermentation. Hotter is quicker, but not necessarily better. Some of the chemical reactions involved in winemaking are long, drawn-out affairs.
Mike
Don't be too concerned about the slight fizz. It could me one of quite a few things, none of them harmful, one of them possibly very beneficial, and it will dissipate anyway in time.
Don't leave growing air gaps as you rack - you should be topping up with water (makes very little difference to the wine). Leave only a small gap between the wine and the bottom of the airlock bung (you're OK to top up right now).
18 degrees C is fine for fermentation. Hotter is quicker, but not necessarily better. Some of the chemical reactions involved in winemaking are long, drawn-out affairs.
Mike
The secret of life is to aim below the head (With thanks to MMM)
Re: Wine fermentation stuck. Boil or campden tablets?
Thanks MKG. That clears that up. Sounds like it's all ok.