Produced CO2 amount during maceration...Difference?

[midilli]

Hi there,

I have attached 2x videos that show the small part of maceration process (i was trying to push the cap while recording).
One video from the last year and the other one for present.
You will see that there is a huge difference with the amount of co2 bubbles produced during maceration.
Both grapes were %100 syrah.

Should i expect the current one has less sugar and producing lower level of co2? Which would lead to low level of alcohol?
Or, is it about the "speed" of the producing process?
Or, not that much important to worry?

Thanks in advance for your help.

 

[winemaker81]

Every ferment is different -- the amount of visible activity is not any useful indicator other than something is happening. Differences can include yeast (even if you're using the same strain), solids in the wine, ambient and must temperature, etc. If your SG is dropping, things are progressing.

 

[Greg Corey]

Less CO2 just means less active fermentation. You’re just enjoying some low and slow fermentation most likely. However one thing to check is if the slowdown is not from lower temperature, smell it regularly and watch out for a sulphur/match/fart smell. That’s a sign of stressed out yeast and something to deal with but otherwise, enjoy the process as it plays out and hopefully some nice aromas from a slower ferment.

 

[midilli]

Less CO2 just means less active fermentation. You’re just enjoying some low and slow fermentation most likely. However one thing to check is if the slowdown is not from lower temperature, smell it regularly and watch out for a sulphur/match/fart smell. That’s a sign of stressed out yeast and something to deal with but otherwise, enjoy the process as it plays out and hopefully some nice aromas from a slower ferment.

Bucket's surface temperature is between 27-28C currently, i believe its fine for maceration, isn't it?
I also smell a thing which i can't describe with words very well but something like sharp wine which is so good =)

Meanwhile, i would like to ask another question: One bucket's s.g. has dropped to 990 and another buckets s.g. is around 1020; would it be OK to mix them in one carboy for fermantation (trying to fill the carboy at high level)?

 

[Greg Corey]

That temperature is totally fine for fermenting and per Bryan's comments, keep watching the SG and as long as it's dropping it's fine but you don't want a stuck ferment, which would be indicated by off smells or SG that doesn't change after a couple of days while there is still sugar in the must. It's possible that you may need some additional nutrients to keep the yeast happy but I doubt it. Just let it go. As for mixing them, yes, that's totally fine. the .990 is definitely ready to rack and as long as you keep a layer of CO2 on top it can wait for the other bucket (or depending on how much headspace you have for your cap to expand, you could just put them all in a bucket together and wait for everything finish fermenting, which would extract even more compounds from the skins, which may be a good thing if that's what you want). You can also just rack both and let the new mixed wine complete it's primary ferment off of the skins. No harm in that at all except for slightly less skin contact, which is opposite from what I said above but may be great, depending on the style you are targeting. Lots of options, all of which depend on equipment and ultimate goals for the flavor. Your instinct to avoid oxygen is the right instinct and the only one that "matters" right now. So feel free to experiment with what you have.

 

[midilli]

Thank you Greg.
It is good to learn for me that i can mix different buckets that have different gravities, this may lead me to experience more taste. I used to think that when the gravity is below 1, i should pass to secondary fermantation stage immidiately.

May i ask a basic question? I now understand when the s.g. is below 1 at the end of primary fermantation, it means that there is no sugar left in the bucket. Correct? Then, if there is no sugar left, what does produce the CO2 during the 2nd fermantation?

 

[Ohio Bob]

There technically is no second fermentation, it’s just a term people have applied when transferring to a second vessel. CO2 is being generated during the entire fermentation and it stays dissolved in solution unless forced out through manual whipping/degassing or slowly over time.

 

[winemaker81]

May i ask a basic question?

Yes -- ask questions before doing. It's far easier to point you to a good path than to fix a problem.

I now understand when the s.g. is below 1 at the end of primary fermantation, it means that there is no sugar left in the bucket.

Adding on to Bob's answer, an SG below 1.000 does not mean there is no sugar. Most wines have a final SG between 0.990 and 0.998, and I've had a couple wines finish at 1.002 for no reason I could determine.

SG is commonly taken as indicating the amount of sugar, but it includes all constituents in a wine. Generally speaking, red wines will have a FG higher that a white because reds have more "stuff" in them.

Generally speaking, if the SG <= 0.998 and unchanging for 3 days, the ferment is considered done. If you're bulk aging for any period (I recommend at least 3 months), any tiny bit of sugar remaining will probably be consumed.

 

[Greg Corey]

Perhaps my statement was confusing. To protect your wine you can artificially add a layer of CO2 either with Dry Ice or a CO2 tank. I only mention it to let you know that you can have a less than full vessel as long as you provide CO2 (or Argon) to displace Oxygen in the vessel. If you mix the two vessels, then the continual fermentation of the batch that isn't complete will provide the CO2 protection layer but you're right, as soon as it is below about .9 then very very little CO2 will be released (even if there is continual fermentation of the last little bits of sugar as Bryan stated).

 

[winemaker81]

One caution when using inert gases -- gases mix very quickly, so adding a "layer" doesn't work.

My theory as to why a degassing wine is safe from oxidation is that the CO2 is continuously emitting from the wine. While the CO2 mixes quickly with the air in the container, the air at the top is pushed out by simple displacement. Over time the mix of gases in the container becomes primarily CO2.

A block of dry ice provides the same effect, as CO2 is constantly subliming, and there's a lot of it. I cannot recall the volume change as CO2 goes from solid to gas, but it's a large factor.

The same is when using argon -- add more than you think you need, as there's no easy way for a home winemaker to determine how much of the headspace is argon and how much is not.

For a wine that was actively degassing, I have left a 5 gallon carboy with 1 gallon of headspace for 5 weeks with no ill results. However, I do not intentionally leave that much headspace nor for more then 3 weeks. The problem with oxidation is that by the time you detect it, it's too late.


EDIT: Qualified the carboy comment

 

[midilli]

There technically is no second fermentation, it’s just a term people have applied when transferring to a second vessel. CO2 is being generated during the entire fermentation and it stays dissolved in solution unless forced out through manual whipping/degassing or slowly over time.

After i gather the grapes from the yard and crash them, i put them all in a bucket and wait approx. 6-7 days until the SG is below 1, i used to call this process as maceration / 1st fermentation. When the SG is below 1, i remove the must and put the juice in a carboy with an airlock, i used to call this process as 2nd fermentation =)

From the messages all i read in here i have now realized that i was totally wrong with the physiology of the process, which i was thinking that fermentation continues during "2nd" stage since the CO2 is goes out through the airlock. Now i see that fermentation is considered done when SG is below 1 with no change for a while and the "2nd" stage is a process which let CO2 to goes out to prevent the bottles to blow =)