Fermentation had stopped before completion

Hi folks,

I'm new to wine making. I have a (red) grapevine, which has produced a good crop this year in the Midlands. So thought I would make some wine. Got the books from the library, followed the directions, I felt pretty well.

The must fermented well in the plastic bucket (SG started at 1.085, after added sugar), after 7 days I put it through a mesh and transferred to a demijohn (SG = 1.026) and put on an airlock. Kept it in the airing cupboard, which seemed nicely warm. But fermentation stopped. SG at 1.025. After 4 days, I tried to restart fermentation by preparing more yeast and adding it to it. But failed.

I'm not sure where to go from here? (From the books, I'm supposed to ferment until the SG is < water.)

Thanks for any help you can give. Sorry if this is a very novice question!

Regards Mike

Reply to
Mike
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It probably would have been best to rack if off the grapes when the SG was near or below 1.000

What I would do know is prepare another starter, and then draw off a litre or two of wine and add this to the starter. Once that is going nicely, add another few litres of wine and make sure it is going nicely. Then you can add that back to the whole lot. Make sure you don't let the wine get too cold either, that's another cause for a stuck ferment! HTH

Reply to
Charles H

When you put "it through a mesh", you most likely lost the majority of the yeast colony, and they couldn't regenerate in a non-aerobic high-alcohol environment. Similarly, you were unable to restart by simply adding yeast, in this environment. Or perhaps all the yeast nutrients were used up.

See "Stuck fermentation" on

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You should have fermented "on the skins" until the SG was around 1.000, and then racked to a secondary container, allowing the wine to "ferment out". The final SG may be as low as 0.990-0.995.

Reply to
Negodki

Another way to help a stuck fermentation is to stir daily. By getting rid of the CO2 and adding the little air that the yeasts require, you keep them at their happiest. Do this for a couple of days after you add the new yeast culture. I found this when fermenting pure sugars--the activity really picked up about an hour after I stirred out the CO2.

The airing cupboard may be the culprit. Many winemakers tend to keep our carboys in corners (on a cement block to save the back) and not in cupboards. Or else the laundry room sink/table gets refitted to be the winemaking station. The lack of freely circulating air probably kept the CO2 too high and killed the yeasts. (it's sort of like dying if your kidneys fail and no dialysis...)

After the primary fermentation, it is OK to hold the carboy at 15-18 C and it is more important to have constant temperature. Any open area that is free of dust or mould will do very well.--Irene

Reply to
Irene

Thanks everyone...and for such a quick reply.

I'll know next year to keeping fermenting on the must until SG water. I checked the books I have, its not clear on this point, inferring simply a set time period.

I'll start a new yeast colony last night, so I'll gradually add the wine to that. Am I then better to put it back into the bucket rather than the demijohn? If O2 is important, I guess having an air lock on a demijohn would also stop fermentation?

Best wishes Mike

Reply to
Mike

Give it 3-4 days in the bucket (time depends on temp). When it suddenyl clears, then rack to the DJ , add airlock, and keep in the open room.

Irene

Reply to
Irene

Irene, There is no question that yeast requires oxygen at the beginning of fermentation, but I am not aware that CO2 can kill yeast or stop an active fermentation. Can you provide a reference? Regards, lum

Reply to
Lum

Did you punch down the cap at least 2 times per day during those 7 days it was fermenting?

Reply to
Steve

I don't remember if CO2 kills the yeast, but if a fermentation is sealed the pressure may become so great that the yeast will stop fermenting. That's not what the original poster had in mind as we're usually talking about fermentation in glass or wood (which would not contain the pressure required to stop a ferment-boom!). Just thought this is an interesting observation that I should share. Warren Place

Reply to
Warren Place

Thanks Warren, that's a good point. I looked up CO2 preservation of juice in Bryce Rankine's book and he says the CO2 pressure needed to prevent fermentation is 6 to 8 atmospheres (90 to 120 psi), so a husky tank is required. lum

Reply to
Lum

yes, a corney keg supposedly has a limit of 150psi. However, I seem to remeber that once the pressure is released, the yeast will begin fermenting again. Warren Place

Reply to
Warren Place

Yes. The 1st 7 days all went well. But I guess the fermentation was not yet complete and I put it in the DJ too soon.

I have tried to restart - gradually (I thought) adding 'wine' to the yeast. It seemed to go well for the first day. All wine was added by day 2, but now day 4 the SG is not reducing?? I guess I'll have to restart and been even slower at adding the 'wine'.

Mike

Reply to
Mike

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