Stuck Fermentation Second Time in a Row

[lukie]

I used to make wine many times in a Fastferment a few years ago and I have never experienced a stuck fermentation.

This time, I bought the SS Brew bucket to ferment my wine and make beer later on (https://www.ssbrewtech.com/products/brewbucket).

I also bought two of these wine kits that I never had before (one Shiraz one Chardonnay): https://www.ontariobeerkegs.com/Fontana_5_5_Lt_premium_wine_kits_Merlot_p/f-prem-merlot.htm

Each time my OG is around 1.08 and after about 1 week I experience a stuck fermentation where the gravity doesn't budge below 1.025 for several days in a row or even weeks later when measured. When making the kit for the first time I just followed the instructions and covered the lid on the brewbucket immediately, clamping the lid down and inserting the air lock.

The second time, that I made the wine, I made sure to stir in all the ingrediants very well for at least 5 minutes with a spoon attached to my screw driver. Then I simply covered the top with the lid (without clamping it down) and I did not put the air lock, covering the hole with a towel to prevent dust from going in. It was left in that state for 4 days. After that I clamped down the lid and put the airlock in. But again, a stuck fermentation.

Both times I kept the Brewbucket in a closet where the temperature is around 23-23.5 Celcius, roughly the same as my room (I live in a condo and don't have a basement). Lastly, I used Starsan for sanitation.

Does anyone know what could be the cause of having these stuck fermentations? Please help.

 

[IslandLizard]

Refractometer or hydrometer?

 

[lukie]

Refractometer or hydrometer?

Good question. Refractometer. A new one I bought here: https://www.amazon.ca/gp/product/B07KVNQ8FG/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

I'm not sure whether it's calibrated, but it shows 0 with water.

Oddly, when I took out the wine from the SS brewbucket after two month it tastes higher than the 7% stuck fermentation would indicate (more like 10%+).

 

[lukie]

I should also state that in neither times did I rehydrate the yeast prior to pitching it. I never rehydrated yeasts before and did not experience any stuck fermentations until making wine in the brewbucket. The problem seems to occur when I clamp down the lid and put the airlock on. Is it possible that it's too air tight and the yeast die out? I'm not sure tbh.

 

[IslandLizard]

Good question. Refractometer.

You just solved your 'problem.'

The reading you get on the refractometer does not reflect the actual gravity, it's inflated once alcohol is present (it has a higher refractive index). You need to use a correction formula to arrive at the actual SG at the moment. To use that formula, you also need to know the OG. Not sure which formula needs to be used for wine, for beer I like to use Sean Terrill's.

Or use a hydrometer.

Hydrometer readings are more straightforward, although at very high alcohol percentages they also show an error, this time due to differences in density.

 

[lukie]

You just solved your 'problem.'

The reading you get on the refractometer does not reflect the actual gravity, it's inflated once alcohol is present (it has a higher refractive index). You need to use a correction formula to arrive at the actual SG at the moment. To use that formula, you also need to know the OG. Not sure which formula needs to be used for wine, for beer I like to use Sean Terrill's.

Or use a hydrometer.

Hydrometer readings are more straightforward, although at very high alcohol percentages they also show an error, this time due to differences in density.

I had no clue, lol. I will now search for the formula. This would explain why the wine tastes significantly higher then the 7% FG would suggest.

I used to have this refractometer and from what I remember I didn't have to do any calculations. It was in BRIX if that makes a difference. https://www.amazon.ca/gp/product/B000FBL2G0/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

 

[lukie]

But also, do it make sense that the wine reaches its final gravity in like 1.5 weeks? Isn't it supposed to be like 3 weeks?

 

[IslandLizard]

I should also state that in neither times did I rehydrate the yeast prior to pitching it. I never rehydrated yeasts before and did not experience any stuck fermentations until making wine in the brewbucket. The problem seems to occur when I clamp down the lid and put the airlock on. Is it possible that it's too air tight and the yeast die out? I'm not sure tbh.

Not sure about wine yeasts, but many dry yeasts for beer now claim not to need rehydration before pitching. Just sprinkle on top of the wort (or must). I'm not convinced rehydration has negative effect when done correctly, haven't seen any conclusive research on it. The manufacturer(s) may use it as advertising, removing another step in the process, making the use of dry yeasts even more accessible.

I reckon wine yeasts also need oxygen at pitching time to be able to replicate, just like beer yeast. Not sure how much and where they get it from. I doubt your stainless bucket's headspace is any smaller than that of a traditional plastic bucket, carboy or demijohn people have been using.

I don't make wine (yet), but have read a lot about it.

 

[IslandLizard]

I used to have this refractometer and from what I remember I didn't have to do any calculations. It was in BRIX if that makes a difference.

AFAIK, every sugar solution measuring refractometer suffers from the alcohol bias, due its inherent measuring system: Refractive index of the liquid presented. It has no way of knowing how much alcohol is in there.

There are also many different kinds of refractometers depending on what liquid is being measured, sugar solutions, honey, salt (reefers), glycol, etc. The systems are all very similar, but the scales are unique to the solution to be measured.

 

[lukie]

AFAIK, every sugar solution measuring refractometer suffers from the alcohol bias, due its inherent measuring system: Refractive index of the liquid presented. It has no way of knowing how much alcohol is in there.

There are also many different kinds of refractometers depending on what liquid is being measured, sugar solutions, honey, salt (reefers), glycol, etc. The systems are all very similar, but the scales are unique to the solution to be measured.

So it's not as simply as taking the OG and FG that the refractometer is giving me and plunking the values into a calculator like this: https://www.brewersfriend.com/abv-calculator/

Hmm, would getting a hydrometer make this more straightforward?

 

[IslandLizard]

But also, do it make sense that the wine reaches its final gravity in like 1.5 weeks? Isn't it supposed to be like 3 weeks?

It's probably the same as with beer, some fermentations are faster than others. Gravity and fermentation temperature are important variables. Controlled and lower ferm temps, especially in the beginning, prevent yeast from binging and leaving lots of byproduct behind that are slow (flavor byproducts) or impossible (higher alcohols) to remove later on.

Similarly to beer, wine that's just done fermenting isn't quite optimal to drink. It improves drastically over the next few weeks as it's conditioning (and clearing). You would rack into a series of 'secondaries,' each time to remove it from the accumulated lees, while it's clearing more.

I'd stick to the 3 weeks in primary before racking. Although you may not see much happening, the yeast 'knows' what to do.

 

[lukie]

I think I found a corrected calculator that seems to make sense here: https://www.petedrinks.com/abv-calculator-refractometer-hydrometer/

According to the corrected calculations, my FG is 1.003. So at least that's very close to the 1.000 required for stabilizing/clearing step. Would you say I am good to go ahead with that step now?

Also, You might be onto something with the temp. I just measured the closet temp after closing the door for 1 hour, and it's saying 23.9 Celcius. Is that considered too high?

 

[IslandLizard]

So it's not as simply as taking the OG and FG that the refractometer is giving me and plunking the values into a calculator like this: https://www.brewersfriend.com/abv-calculator/

Hmm, would getting a hydrometer make this more straightforward?

That calculator is for hydrometer, or corrected refractometer, gravity (SG or Brix) readings.

This is the calculator to correct your refractometer reading when alcohol is present:
https://www.brewersfriend.com/refractometer-calculator/
Read the notes on the bottom carefully.

Yes, hydrometer readings are usually correct as is, unless the alcohol starts to exceed 20% or so.

The beauty of a refractometer is it only requires one single drop, not 3 oz per sample.
Each time you take 3 oz of wine out, 3 oz of air gets back in (usually much more with a wine thief). So refractometers are handy for keeping track of progress.

But for a final reading I'd rely on a hydrometer. Then correlate that with the refractometer (after applying the correction formula) to see how far they are actually apart. Adjust for that when taking future readings. You should get closer to the pin with each successive batch that way.

 

[IslandLizard]

I think I found a corrected calculator that seems to make sense here: https://www.petedrinks.com/abv-calculator-refractometer-hydrometer/

According to the corrected calculations, my FG is 1.003. So at least that's very close to the 1.000 required for stabilizing/clearing step. Would you say I am good to go ahead with that step now?

Also, You might be onto something with the temp. I just measured the closet temp after closing the door for 1 hour, and it's saying 23.9 Celcius. Is that considered too high?

That calculator looks very useful, sure!

Just make a note, when I see the field 'wort correction factor,' it points to beer (wort) which is not the same as wine must (different sugars etc.).
So that (wort) correction factor (usually 1.040) may not apply to readings from wine.

If it's been in there for 3 weeks and starts clearing it's probably time to think about racking to a secondary. That's also the best time to take your hydrometer sample. Degas and take to calibration temp before measuring. Then drink it to test the flavor and overall quality.

Yeah, 24C is a bit high for early fermentation stages, the first 1-2 weeks. But it's a good temp for letting her finish up for a week, or 2 weeks if needed after the big job is done. If it's the same for wine as for beer, warming up a few degrees toward the end, when bubbling has slowed down significantly, is a good thing to keep her active, so she won't stall out prematurely.

 

[lukie]

That calculator looks very useful, sure!

Just make a note, when I see the field 'wort correction factor,' it points to beer (wort) which is not the same as wine must (different sugars etc.).
So that (wort) correction factor (usually 1.040) may not apply to readings from wine.

If it's been in there for 3 weeks and starts clearing it's probably time to think about racking to a secondary. That's also the best time to take your hydrometer sample. Degas and take to calibration temp before measuring. Then drink it to test the flavor and overall quality.

Yeah, 24C is a bit high for early fermentation stages, the first 1-2 weeks. But it's a good temp for letting her finish up for a week, or 2 weeks if needed after the big job is done. If it's the same for wine as for beer, warming up a few degrees toward the end, when bubbling has slowed down significantly, is a good thing to keep her active, so she won't stall out prematurely.

Thanks for your help. For me the wort correction factor on that calculator shows up as 1. I wonder if that's okay for wine.

As for racking to secondary, I never do that because right from the start of this hobby I was always dealing with conical fermentors like Fastferment and now this Brewbucket due to limited space in a condo. So after about 30 days, the wine goes into bottles.

Next time, I will try to bring the brewbucket out of the closet for the first week or so and see if there's a difference in terms of fermenting time.

 

[lukie]

I also found this handy dandy Excel calculator for wine: http://valleyvintner.com/Refrac_Hydro/Refract_Hydro.htm

It deals with starting Brix, so I just translated the SG readings on my refractometer into Brix using this table here: https://www.winning-homebrew.com/specific-gravity-to-brix.html

When I put in the starting Brix of 19.3 (i.e., 1.080 OG), it gives me an adjusted FG of .0993, which is good (if I did it correctly)!