Fermentation halted?

[Drez]

Hello all

I grew up surrounded by a lot of wine making. On my own I've done a couple batches in the shop where your not really doing much other than bottle. Recently I started my own batch at home and am quite excited about it.

I am however concerned that fermentation may have halted. Your help would be appreciated.

Started SG was 1.090~
Currently 1.030~
Wine is a Sharaz from Wine Kitz, its a 5 week batch in a 6.5gal fermentation bucket, sealed on top with an airlock. Temp has been aprox. 20 degrees C consistently in the room its being made.

Its now been 16 days and I'm still only aprox 2/3 done fermenting the sugars away, I was suspecting to be at SG 1.0 a couple days ago. Is fermentation halted? Can I restart it with more yeast? I seem to have lots of sugars left to consume. How might this have happened. If I went overboard insuring everything was sterilized with sulphites could I have killed off my yeast with it?

Thanks in advance

 

[robie]

Sounds like it is stuck. The SG is too high for it to be even near finished.

If the sulfite level had been too much, the fermentation would never have started.

I'd open the lid and stir in a lot of oxygen (big stir!). At 1.030 it still needs some air.
I'd put a brewbelt on or whatever else you have to increase the temperature to about 75 degrees F.

If you add more yeas without rehydrating it and acclimating it to the alcohol already in the wine, it likely will die immediately. We can tell you how to acclimate the yeast, but not yet, try adding some air and temperature first.

After you do this, let us know how it's going.

 

[Dugger]

It doesn't sound like there is a problem - try to increase the temp to about 24 degrees and this should speed it along. Take some SG readings and it should show that it is fermenting. It's unusual to get a stuck fermentation with a kit unless it gets really cold or really hot. If you had oversulphited, the yeast would not have started at all.
Good luck and welcome to the forum!
Gonna be an interesting vote up there next week on the gun bill, eh!

 

[robie]

16 days and only down to 1.030 is not typical, even for that lower temperature.
What yeast came with the kit? Is that the yeast you used? Don't know that particular kit - does it call for a yeast nutrient to be used?

 

[Drez]

If you had oversulphited, the yeast would not have started at all.

Good luck and welcome to the forum!

Gonna be an interesting vote up there next week on the gun bill, eh!

That's good to know. I wasn't sure it a small amount might kill everything or just some of it.

Thanks for the welcome, always happy to see other Canucks on global forums. As for the vote, I'm sure we'll see some sort of drama either way, that seems to be how it goes most of the time here in the capital.

16 days and only down to 1.030 is not typical, even for that lower temperature.

What yeast came with the kit? Is that the yeast you used? Don't know that particular kit - does it call for a yeast nutrient to be used?

I didn't think so. I used the yeast that came with the kit. I may have thrown out the package but I'll try to find the genus/species. It did not call for a nutrient.

Sounds like it is stuck. The SG is too high for it to be even near finished.

If the sulfite level had been too much, the fermentation would never have started.

I'd open the lid and stir in a lot of oxygen (big stir!). At 1.030 it still needs some air.

Feared as much. I'll give it a mighty stir and leave the lid on rather loose. I was so concerned about contamination that I had not considered oxygen. I'll try this and report back.

 

[robie]

The extra heat (and air) can make a big difference. If no nutrient was called for, the yeast is likely a pretty hardy one, as the kit makers don't take many chances with yeasts that tend to get stuck.

Most people don't realize that during the time a wine is in the primary, it needs some oxygen to ferment. Lots of people get by with completely sealing the primary, but I don't know how. If the kit has a grape pack, they have to open the fermentor at least once a day to punch down the cap. Punching down adds enough air to get by, I guess.

When the wine is racked to its secondary at an SG around 1.000 to 1.020, the yeast are at a stage where they no longer want access to oxygen. That's why you rack to a carboy and add the airlock at secondary. The wine doesn't typically need topped-up in secondary because there is still lots of CO2 being produced and it protects the wine from any oxygen.

As I said earlier, at this point don't try pitching more yeast without acclimating it to the alcohol that's already in the wine. I doubt you will need to pitch more yeast.

 

[Drez]

The yeast package is thrown out it seems but I'm sure your right. I gave it a good stir and will measure up again tomorrow, I dont have a heat source really other than a fish heater which is proabably not the right tool, seraile or not. If this does not work I may need to invest in one.

I will report back in a day or two see if matters change.

 

[robie]

You can put the fish tank heater in a large jar or bottle and float it in your fermentor.

Another way is to put the fermentor bucket inside a large tub.
Fill the tub with water and place the heater in the tub. This will take awhile before it heats up the must.

Some even wrap a heating pad around the fermentor; just make sure the pad stays dry. Be careful, though!!!

 

[Dugger]

Good point on the oxygen, Robie. I also use a loose lid until it gets to about 1010.
Heat belts are great to keep the bucket warm, but most times I just wrap an insulated shirt around it and the heat from the fermentation keeps the temp up. If you can get it warmed up, Drez, try wrapping it with something. Also, make sure it is up off the floor, preferably sitting on a piece of insulation.

 

[Drez]

Will do

Haha two weeks ago I would have been worried about it being too warm lol

 

[Drez]

So I think its officially halted. Been stuck at SG 1.030 now for a little while. Wine store suggested I rack it down and add some more yeast (EC-1118 Saccharomyces Bayanus) after hydrating it and that I warm the carboy up some. Any additions or is that my best bet at this point?

Thanks

 

[robie]

After all you have done, sounds like adding yeast is the thing to do. You will need a special yeast starter for this, as there is already alcohol, which can shock and kill the new yeast.

Make a yeast starter. Once the water/yeast starts becoming active, add 2 tablespoons of reconstituted grape juice to the mixture. Wait about 30 minutes and add 4 tablespoons.

Wait 30 minutes more and add 2 tablespoons OF YOUR STUCK WINE MUST to the mixture. In 30 minutes, add 4 tabespoons of it.

Wait 30 minutes and add 1/4 cup of your must. Repeat this step 2 more times. Always make sure there is bubbling and activity within a few minutes of adding to the mixture.

Making sure the yeast starter is within a couple degrees of the must in the fermentation bucket, slowly stir this acclimated yeast starter into your fermentation. Signs of fermentation should start within 8 hours.

 

[Drez]

Awesome, thanks

 

[Drez]

So interesting update and good FYI for others who might end up in this situation, turns out my fermentation wasn't halted. I was using a refractometer to measure SG and as I now understand alcohol effects the bending of light and can throw off your readings, after corrections my SG of 1.030 was actually under 1.000 and so I had simply finished fermenting. I've racked down, stabilized and in a month or so I should have some bottled wine!

Here is a link provided to me by a forum member here with some helpful info on refractometers that allowed me to solve this and a spreadsheet for the future:
http://wijnmaker.blogspot.com/2010/04/refractometer.html