Home Brew Forums

Home Brew Forums (http://www.homebrewtalk.com/forum.php)
-   Wine Making Forum (http://www.homebrewtalk.com/f25/)
-   -   Incomplete fermentation (http://www.homebrewtalk.com/f25/incomplete-fermentation-354197/)

lswpubrw 09-14-2012 12:14 AM

Incomplete fermentation
 
I have some raspberry wine started in 2009 and another batch started in 2010. We generally leave the wine fermenting all year in the basement next to the oil burner so the temperature is 65 to 72 degrees. We bottle it after one year. Most of the time the fermentation is complete, but in these last two years I've had problems with gas accumulating and blowing out the corks. What keeps the fermentation from going to completion in one year?

Bob

ggoodman 09-14-2012 05:12 AM

wrong forum

lswpubrw 09-14-2012 08:15 PM

Incomplete fermentation
 
I have some raspberry wine started in 2009 and another batch started in 2010. We generally leave the wine fermenting all year in the basement next to the oil burner so the temperature is 65 to 72 degrees. We bottle it after one year. Most of the time the fermentation is complete, but in these last two years I've had problems with gas accumulating and blowing out the corks. What keeps the fermentation from going to completion in one year?

Bob

Yooper 09-14-2012 11:57 PM

Quote:

Originally Posted by lswpubrw (Post 4413642)
I have some raspberry wine started in 2009 and another batch started in 2010. We generally leave the wine fermenting all year in the basement next to the oil burner so the temperature is 65 to 72 degrees. We bottle it after one year. Most of the time the fermentation is complete, but in these last two years I've had problems with gas accumulating and blowing out the corks. What keeps the fermentation from going to completion in one year?

Bob

I can't think of anything! It should be complete within a few days, let alone a year!

Do you take any SG readings? That's the only way to know for sure if the fermentation finished.

A cause of popped corks could be gas in the wine when it's bottled, and then the temperature changes, but after a year of sitting in a carboy under airlock it should be pretty well degassed naturally.

It's possible that you're undergoing spontaneous MLF in the bottle, if you have sulfited to prevent it. That would cause the corks to pop, as well as some infections.

saramc 09-15-2012 12:52 AM

Raspberry is known for kicking out H2S and for being quite acidic...that could have stalled your ferment. Are you not using a hydrometer? Corks blowing after bottling could be cause by failure to degas the wine prior to bottling or refermentation.
Did you add any fermentable sugar for backsweetening...if so did you stabilize with sorbate + k-meta?

amandabab 09-15-2012 07:22 AM

the fermentation is most likely complete, but you don't mention degassing it.
Not degassing will cause corks to pop.

Yooper 09-15-2012 12:46 PM

Or, as saramc mentioned, adding additional fermentables to an unstabilized wine would do it! If the wine was sweetened, but not racked off the lees and stabilized with sorbate, fermentation would certainly restart.

Jacob_Marley 09-15-2012 07:25 PM

Sounds from your description like the wine sat on the lees for a very long time.
Nutrients released from the wine sitting on the lees (i.e. autolysis) might support a slight, long-term fermentation on any residual sugars.
Nutrients released from autolysis will also support MLF, however citric is the far prominent acid in raspberries ... the malic is fairly minor. However, MLF does act on both citric and malic ... the metabolization of citric resulting in acetic acid. Has there been any change in the taste toward a bit of vinegar?
MLF might not be terribly likely though.

Did you fine ... or stabilize ... or both? Fining helps to reduce nutrient content and of course sufliting & sorbating helps put an end to most further fermentations.

In any regard, keeping your bottles in a cooler area if possible may help cure the current problem.
In the future, making sure the wine is racked off of any lees as they settle might help ... possibly with the final few months done judiciously using fining agents.

Is the level of carbonation really unacceptably high for the bottles you're using? ... You could just get some baskets (or wire) and tie them suckers down and keep the wine stored in a cool'ish area. I like fizzy wine ;-)

lswpubrw 09-16-2012 02:26 PM

Well thanks for all the suggestions. What puzzled me is we've used the same technique for years with an occasional "fizzy" wine resulting. We do sulfite the "mash" before fermentation and sterilize the bottles. We've never produced vinegar. We're pretty much amateurs and have not done things measuring SG although I have a hygrometer.
Let me provide more details. We follow a method from a book by H.E.Bravery called Succesful Winemaking at Home. We mash up the berries, add water and Camden tablets and let sit for 24 hr in a plastic barrel with occasional stirring. Then berries are juiced (strained through clothe) sugar water is added along with yeast and allowed to ferment for 10 days. Sediment is left at the bottom of the barrel and the fluid transfered to air locked glass carboys and more sugar added. This sits for 14 days at which time more sugar water is added as the final stage and the mix allowed to ferment/age for about 10 months in the basement next to the oil burner. The temperature remains between 65 and 72 for the duration. This is method has served us well over the years.

1. I have opened the bottles, consolidated back into a sterilized carboy and find that when I shake the carboy I get much gas out but if I don't shake I see no bubbles. It takes about 3 or 4 days of doing this several times a day for the degassing to stop. Seems as it the shaking accelerates the gas evolution. Is there a clue in that? Is this soemthing I need to do before the original bottling? Several people mention degassing before bottling, is this what is being referred to? I did shake the carboys occasionally and do remember seeing foam produced over the year that they sat before bottling. We are careful about leaving the lees behind when we transfer.

2. We do not add any sugar after the final amount which is by the 24th day. We also have never tried stabilization techniques. From what I read we should be adding potassium sorbate before bottleing?

3. I just measured the SG using my hydrometer and get somewhere between 0.99 and 1.00.

Thanks,

Bob

Jacob_Marley 09-16-2012 07:11 PM

Quote:

Originally Posted by lswpubrw (Post 4417005)
Well thanks for all the suggestions. What puzzled me is we've used the same technique for years with an occasional "fizzy" wine resulting. We do sulfite the "mash" before fermentation and sterilize the bottles. We've never produced vinegar. We're pretty much amateurs and have not done things measuring SG although I have a hygrometer.
Let me provide more details. We follow a method from a book by H.E.Bravery called Succesful Winemaking at Home. We mash up the berries, add water and Camden tablets and let sit for 24 hr in a plastic barrel with occasional stirring. Then berries are juiced (strained through clothe) sugar water is added along with yeast and allowed to ferment for 10 days. Sediment is left at the bottom of the barrel and the fluid transferred to air locked glass carboys and more sugar added. This sits for 14 days at which time more sugar water is added as the final stage and the mix allowed to ferment/age for about 10 months in the basement next to the oil burner. The temperature remains between 65 and 72 for the duration. This is method has served us well over the years.

1. I have opened the bottles, consolidated back into a sterilized carboy and find that when I shake the carboy I get much gas out but if I don't shake I see no bubbles. It takes about 3 or 4 days of doing this several times a day for the degassing to stop. Seems as it the shaking accelerates the gas evolution. Is there a clue in that? Is this soemthing I need to do before the original bottling? Several people mention degassing before bottling, is this what is being referred to? I did shake the carboys occasionally and do remember seeing foam produced over the year that they sat before bottling. We are careful about leaving the lees behind when we transfer.

2. We do not add any sugar after the final amount which is by the 24th day. We also have never tried stabilization techniques. From what I read we should be adding potassium sorbate before bottleing?

3. I just measured the SG using my hydrometer and get somewhere between 0.99 and 1.00.

Thanks,

Bob

Hello Bob,

Your method, while fine generally speaking, might be a bit ‘spare’ in some ways by some current practices ... that is, there are other actions you ought to add to improve the process. In particular ... keeping track of the SG or sugar - sulfiting at certain times - and understanding fermentation temperature and keeping the maturing must off of the sediment or lees.

Some comments in no particular order ...

That is a very good step to be sulfiting your must before pitching the yeast (“must” is the name in winemaking of what you called “mash”).

The device you measure the sugar in your must with is a hydrometer, with a “d” ... rather than a hygrometer, with a “g”.
A hygrometer is in my cigar humidor ... the hydrometer is in my wine kit.
With a hydrometer, it is *very* useful to measure (and record) the relative sugar in the must periodically throughout the process ... really, it is a requirement as far as I’m concerned. This is for figuring out problems, for knowing more about the percentage alcohol in your wine ... which has to do with everything from shelf life to resistance to spoilage to yeast selection ... etc etc, understanding where your ferment is at in the process at any time, and so many other aspects. Just a very good practice.

While I still suspect the autolysis/nutrient issue mentioned in my previous post ... the issue of fizz happening in some years and not others may be, in part, the result of the average temperature during ferment.
The lower the average temperature during the whole of primary fermentation (typically the first 5 days to 2 or so weeks) the more carbon dioxide will be stored in the must, and conversely the higher the temperature of the must, the less carbon dioxide will be kept or “dissolved into” the must.
And so, higher temp ferments will need a bit less degassing to rid them of fizz.
65* to 72* would not be considered in the higher end of the range, and so could be leaving some extra fizz in the wine. True, it does degass over time while under airlock, but as you noted with the fizzing when shaken, it may not degass entirely.

If you look online at the spec sheet for the yeast you are using you will see the “recommended temperature range” for the must when using that yeast. This will, in part, tell you what higher or lower temperature ranges you will likely have success at using that yeast. While you are reading that spec sheet it would also be invaluable to investigate ... even just for cursory knowledge ... each of the specific characteristics for that yeast on the list there regarding temperature - alcohol range - and so forth.
A good way to start getting familiar with an important part of winemaking ... yeast.

That secondary ferment you are doing after adding sugar the second time is a true secondary fermentation. This is the “root” so to speak of referring to the racking from the primary fermenter into another carboy as a “secondary” ... which might have residual fermentation going on from the primary ... or can have a whole other new, induced fermentation as you do.
Adding that additional sugar for a secondary fermentation is a procedure more common in the way of making sparkling wine called “method champenoise” which is done in the bottle ... in brewing this is “bottle conditioning”. An induced secondary fermentation might also be for other reasons involving alcohol content and the specifics of using various yeasts. As well a "secondary fermentation" can also refer to intentional MaloLactic Fermentation in the secondary fermenter.
In any regard, the practice you are using is fine ... like they say, if it ain't broken ...

Importantly, regarding the degassing you are currently doing by shaking, stirring, splashing, transferring back to the carboy to put under airlock etc ...
That action of degassing is fine, BUT you are exposing your wine to a great deal more oxygen with this process. For this reason you absolutely have to hit your wine with a standard dose of sulfites before rebottling. This would be the dose that can be read on the bottle of Potassium Metabisulfite powder, Sodium Metabisulfite powder, or Campden tablets that you get from the supply house.

>> We also have never tried stabilization techniques. From what I read we should be adding potassium sorbate before bottling?

Stabilization usually has to do with both adding certain chemicals ... metabisulfite and potassium sorbate ... as well as the act of fining/clarifying, which removes dead yeast, bacteria, tannins, pectin and other junk ... fining/clarifying can be done by both adding chemicals that help the process ... and/or waiting, waiting and more waiting for things to fall to the bottom on their own and then racking the clear wine off the sediment into new bottles/carboys etc.

As far as Sorbate ... some people don’t like to add sorbate as it can add certain off flavors, particularly under certain circumstances. Furthermore, sorbating is not totally necessary if you have managed to arrest/stop the fermentation by other means ... most commonly by letting all the sugars get used up resulting in a dry wine. If you are bottling a wine with any sweetness, I’d say it is probably a good practice to carefully go through the process of adding sorbate to prevent further fermentation and pressurization of the bottles ... you don’t want popping corks and wine geysers, and certainly not raspberry hand grenades.
You stated your wine is now at 0.990 ... this is "dry" and has effectively no residual sugar ... so, no you do not need to add sorbate. (though you do need to add metabisulfite)

The other chemical used at stabilization is metabisulfite, and adding it is a good practice, particularly for the casual winemaker.
Many winemakers add metabisulfite before ferment as you do; then often a bit more (say, a quarter or half of a standard dose) when they transfer the wine into the secondary ... then very frequently more when they actually bottle.
This description is approximate as the use of sulfites can be quite technical and so I’ll leave that discussion out of this already very long post. Suffice it to say it is good, cheap insurance to add sulfites periodically throughout the process.

Hope all this helps.


All times are GMT. The time now is 09:34 AM.

Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.