Carbonic maceration: strange secondary fermentation

[Forbidden Garden]

Hello, i hope for advice.
I'm not sure if fermentation is going well. I made carbonic whole cluster maceration in plastic 43 liter fermenter. Before filling CO2 gas, i filled the fermenter with warm water, with 200ppm sulfur dioxide added, and pH adjusted to 3,5; to make sure grapes will not be affected with unwanted yeasts or bacterias. After two hours I drained the water and filled the fermenter with CO2 gas, reintroducing CO2 twice daily and keeping it hermetically closed for about a week. After that, i destemmed and crushed the grapes. Funny thing- the grapes were gaseous, they were full of CO2, like a lemonade, but still clusters were intact and fresh-looking, and tasting also fresh, and the smell was fantastic. After crushing, i added 50ppm sulfur dioxide (Campden) to the must, and had to wait some time before adding yeast. The strange thing was, that after 15-18 hours, the must looked like the fermentation was already going- the cap was formed, and when mixing the must, a huge amount of CO2 was releasing- much more that in normal, conventional wine fermentation. I added the yeast anyway. I suspect, that fermentation started before i added the yeast.. what means, that fermentation is done by wild yeast. Could it be, that sulfiting whole clusters before carbonic maceration did not help, and there were yeast present on grapes all the time? And also addition of sulfur to the freshly crushed must did not affect and did not kill yeasts which were present in the must? I'm not sure if i can do anything now. How could i know, if wild or my added yeast is working now? It's first time i try to make carbonic maceration. Have read about this method in one research article, but i am not sure the method is right. Maybe someone could have some insights about this situation, or could tell what i did wrong? There are two more fermenters with carbonic maceration, still with CO2 gas, and i don't want to ruin them.

 

[stickman]

I have not done carbonic maceration, so no experience here, but from what I have researched, a small percentage of actively fermenting must (yeast of your choice) is typically added to the bottom of the fermenter, fill the fermenter with whole berries or whole clusters etc., close the tank and purge with CO2, allow the carbonic maceration to take place for several days, maybe a week, then crush grapes and add back to the tank and continue fermentation. Do not add sulfur dioxide to the wine during the process.

 

[Forbidden Garden]

Thank you for the answer. I have not done carbonic maceration, so no experience here, but from what I have researched, a small percentage of actively fermenting must (yeast of your choice) is typically added to the bottom of the fermenter, fill the fermenter with whole berries or whole clusters etc., close the tank and purge with CO2, allow the carbonic maceration to take place for several days, maybe a week, then crush grapes and add back to the tank and continue fermentation. Do not add sulfur dioxide to the wine during the process.

If some fermenting must, or juice/crushed grapes inoculated with yeast is added to the bottom of the tank, it is then called a semi-carbonic maceration. I did not add anything to the bottom of the tank, trying to keep the clusters dry. There was some juice from occasionally crushed grapes, but not more than 180ml. at the end of the process.

 

[Vinobeau]

Here is the link to the thread that I started when I made a Wild Grape Carbonic Maceration last year. Carbonic Maceration
I started with the wild yeast that created the CO2, and I shortened up the 4 - 5 weeks of prelim fermentation to 2 weeks. I was disappointed with the end product, but perhaps it was because I used Wild Grapes.

 

[sour_grapes]

I don't understand. Why did you add yeast to something that you are aiming to call carbonic maceration? From your response to @stickman , it appears that you know these aren't the same thing.

 

[Snafflebit]

During carbonic maceration the fermentation is happening inside the grape cells as the grape cells themselves metabolize sugar in an oxygen free environment. Your wine is “double fermented” in a sense. How does it taste?

 

[Cynewulf]

I don't understand. Why did you add yeast to something that you are aiming to call carbonic maceration? From your response to @stickman , it appears that you know these aren't the same thing.

The berries will burst when they reach 2% alcohol. They’re usually pressed then and fermentation is finished with yeast: What is Carbonic Maceration? | Wine Enthusiast.

 

[Forbidden Garden]

I don't understand. Why did you add yeast to something that you are aiming to call carbonic maceration? From your response to @stickman , it appears that you know these aren't the same thing.

Carbonic maceration process could be divided into two parts,
1)- Letting whole intact clusters stay at C02 atmosphere. It can be done in different ways, one is to simply add C02 gas, other is to put some fermenting must to the bottom of the vessel, and it will produce C02 in a fermentation process, slowly filling the vessel with this gas to the top.
2)- After finishing first part, grapes are destemmed, crushed, and fermented in normal way. This also can be done either with native yeast, or by adding the yeast of winemaker's choice.

to make things more clear, i add an article about processes that are happening (or should happen) in carbonic maceration: Carbonic maceration: a closer look at this winemaking technique

What i tried to do: On the first part of the process, i chose to make a full carbonic maceration, by this i mean, that i did not want to start a regular yeast fermentation on the bottom of the vessel. I added intact clusters to fermenter, and added CO2 gas. After first part, i acted as if i am starting to prepare a must for normal fermentation: destemmed and crushed grapes, added 50ppm sulfur dioxide, and after 18 hours i added yeast.
I thought that normal yeast fermentation will not start on the first part of the process- while intact clusters were kept in C02 atmosphere. Maybe i was wrong, and the yeast fermentation started? While reading various articles about the process, i made conclusions, that carbonic atmosphere will not let the process of normal yeast fermentation to begin. Maybe i was wrong? Theoretically, the processes that should take place in C02 atmosphere, is anaerobic metabolism, with malic acid being transformed into succinic acid and ethanol, up to 2% of alcohol content. Up to 50% of malic acid can be transformed during this phase.
I checked the Brix of grapes before and after the first part of carbonic maceration. 2% of alcohol was produced during this phase- exactly as it is described in articles. Also, i measured TA. It was reduced from 8,7g/l. to 7,1g/l. this is what i was expecting from carbonic maceration, and why i wanted to try this method. I live in a cool climate region, and big acidity is main problem here. Now the main question is, why the second part of the process- normal yeast fermentation, looks so dramatically different from the normal yeast fermentation- huge amounts of C02 is being released. I keep fermenter in rather cool conditions, that would be 59F, with the temperature of the must 62F.
I also have to say, that with half of the grapes (Cascade variety) i made normal yeast fermentation from the start, and half was for carbonic maceration experiment. In normal yeast fermentation with my added yeast, the fermentation process was normal, and the amount of C02 released while punching down the cap and mixing, was really less than what i have now with the must from carbonic maceration. That is why i doubt, if everything is ok with that must.

 

[stickman]

According to the resource I have, Knowing and Making Wine, by Emile Peynaud, it indicates that on a commercial scale, "the grapes are crushed by their own weight gradually and normal fermentation keeps up the required carbon dioxide atmosphere. Extraction may last 8 to 10 days or more. The volume of free run juice varies at racking between 50% and 75% of the total volume. Its fermentation is very nearly complete. Its been determined that approximately 20% of the grapes are crushed and undergo alcoholic fermentation by the yeasts, 20% of the grapes remain intact and become centers for intracellular fermentation, and the remaining 60% undergoes both transformations. The press wine, still with sugar, is mixed with the free run wine. Normally fermentation finishes in 48 hours."

 

[Cynewulf]

Carbonic maceration process could be divided into two parts,
1)- Letting whole intact clusters stay at C02 atmosphere. It can be done in different ways, one is to simply add C02 gas, other is to put some fermenting must to the bottom of the vessel, and it will produce C02 in a fermentation process, slowly filling the vessel with this gas to the top.
2)- After finishing first part, grapes are destemmed, crushed, and fermented in normal way. This also can be done either with native yeast, or by adding the yeast of winemaker's choice.

to make things more clear, i add an article about processes that are happening (or should happen) in carbonic maceration: Carbonic maceration: a closer look at this winemaking technique

What i tried to do: On the first part of the process, i chose to make a full carbonic maceration, by this i mean, that i did not want to start a regular yeast fermentation on the bottom of the vessel. I added intact clusters to fermenter, and added CO2 gas. After first part, i acted as if i am starting to prepare a must for normal fermentation: destemmed and crushed grapes, added 50ppm sulfur dioxide, and after 18 hours i added yeast.
I thought that normal yeast fermentation will not start on the first part of the process- while intact clusters were kept in C02 atmosphere. Maybe i was wrong, and the yeast fermentation started? While reading various articles about the process, i made conclusions, that carbonic atmosphere will not let the process of normal yeast fermentation to begin. Maybe i was wrong? Theoretically, the processes that should take place in C02 atmosphere, is anaerobic metabolism, with malic acid being transformed into succinic acid and ethanol, up to 2% of alcohol content. Up to 50% of malic acid can be transformed during this phase.
I checked the Brix of grapes before and after the first part of carbonic maceration. 2% of alcohol was produced during this phase- exactly as it is described in articles. Also, i measured TA. It was reduced from 8,7g/l. to 7,1g/l. this is what i was expecting from carbonic maceration, and why i wanted to try this method. I live in a cool climate region, and big acidity is main problem here. Now the main question is, why the second part of the process- normal yeast fermentation, looks so dramatically different from the normal yeast fermentation- huge amounts of C02 is being released. I keep fermenter in rather cool conditions, that would be 59F, with the temperature of the must 62F.
I also have to say, that with half of the grapes (Cascade variety) i made normal yeast fermentation from the start, and half was for carbonic maceration experiment. In normal yeast fermentation with my added yeast, the fermentation process was normal, and the amount of C02 released while punching down the cap and mixing, was really less than what i have now with the must from carbonic maceration. That is why i doubt, if everything is ok with that must.

Thanks for sharing your experience with carbonic maceration. It’s something I want to try next year with my Marquette grapes for the same reason you did: to reduce the malic acid naturally. Are you able to share any pictures of your process? To your original question regarding whether your fermentation is proceeding with the wild/ambient yeast or the cultivated yeast you added, I don’t think anyone is going to be able to tell you without cultures and laboratory analysis.

 

[Forbidden Garden]

Checked the Brix in fermenting must. The fermentation is almost finished, due to results. Also, i measured TA, and it really makes me upset. Before fermentation TA was 7,1 g/l. Now TA is 9,5 g/l. I would really want to know, what is happening there. The taste is sour, but not aggressively sour.

 

[Cynewulf]

Checked the Brix in fermenting must. The fermentation is almost finished, due to results. Also, i measured TA, and it really makes me upset. Before fermentation TA was 7,1 g/l. Now TA is 9,5 g/l. I would really want to know, what is happening there. The taste is sour, but not aggressively sour.

Did you degas the wine before testing the TA?

 

[Forbidden Garden]

Did you degas the wine before testing the TA?

Yes, i punched down the cap, mixed everything, and then took a sample. Maybe i will measure once again soon, just to be sure.

 

[Forbidden Garden]

This time i strained off the sample to get more homogenous liquid, and degassed it carefully. I got TA 8 g/l. Still, more than before fermentation.
Could it be, that after some time when fermentation will be absolutely over, TA level will drop considerably? Or is this higher TA a result of some unwanted processes. Maybe it is possible to guess, what could cause it?

 

[Ajmassa]

This time i strained off the sample to get more homogenous liquid, and degassed it carefully. I got TA 8 g/l. Still, more than before fermentation.
Could it be, that after some time when fermentation will be absolutely over, TA level will drop considerably? Or is this higher TA a result of some unwanted processes. Maybe it is possible to guess, what could cause it?

Who knows man. There’s so much happening in Carbonic Maceration, and so many different ways to go about it, it’s almost impossible to know exactly what’s goin on in there IMO. I’m no chemist. Usually it’s being done by a winemaker who is already extremely familiar with their grapes, and will be able to determine CM’s effects. I don’t test acid during AF. I don’t see the point. Plus it’s pain just to properly prepare a sample.

I tried this out on a small scale—-with crushed must over top 30% whole clusters. Pressed wine I assume had more intercellular fermentation goin on as juice released. Theoretically should result in a lower TA *I think. Idk. Numbers are almost the same. Impossible to really know. I’m just a home winemaker with a very basic understanding of it. I did it just for fun and hoping to make a big wine more approachable early. I believe my use of enzymes + all those stems + my high abv nullified any CM benefits. (Good to know for the future though)

I probably wouldn’t do whole cluster/CM again. But I’m glad I did it. Things like CM/whole cluster, saigneé, cold soak, delestage etc — all just little fun things to experiment with. But since I’m getting different grapes every year and not making a controlled batch it’s difficult to really confirm the effects. My hope is that if I tinker around enough there might come a day many years from now where I can get grapes and confidently make decisions that will benefit the wine. As opposed to- experimenting while trying to keep the wine from being terrible lol.

 

[Forbidden Garden]

Who knows man. There’s so much happening in Carbonic Maceration, and so many different ways to go about it, it’s almost impossible to know exactly what’s goin on in there IMO. I’m no chemist. Usually it’s being done by a winemaker who is already extremely familiar with their grapes, and will be able to determine CM’s effects. I don’t test acid during AF. I don’t see the point. Plus it’s pain just to properly prepare a sample.

I tried this out on a small scale—-with crushed must over top 30% whole clusters. Pressed wine I assume had more intercellular fermentation goin on as juice released. Theoretically should result in a lower TA *I think. Idk. Numbers are almost the same. Impossible to really know. I’m just a home winemaker with a very basic understanding of it. I did it just for fun and hoping to make a big wine more approachable early. I believe my use of enzymes + all those stems + my high abv nullified any CM benefits. (Good to know for the future though)

I probably wouldn’t do whole cluster/CM again. But I’m glad I did it. Things like CM/whole cluster, saigneé, cold soak, delestage etc — all just little fun things to experiment with. But since I’m getting different grapes every year and not making a controlled batch it’s difficult to really confirm the effects. My hope is that if I tinker around enough there might come a day many years from now where I can get grapes and confidently make decisions that will benefit the wine. As opposed to- experimenting while trying to keep the wine from being terrible lol.

Yes, there are many different ways to do it. Sad, but i did not meet (virtually, on internet) not even one person, who tried to do not semi-carbonic maceration, but carbonic one- without adding fermenting must to the bottom of the vessel. So i know only theoretically, how it should be done. On most sources, carbonic maceration is being done in a bigger wineries, in a bigger vessels, where clusters on the bottom will crush unavoidably because of bigger weight beneath them. When doing this on a small scale, there are all possibilities to avoid free run juice on the bottom.
"I believe my use of enzymes + all those stems + my high abv nullified any CM benefits "
What could easily damage CM benefits, which also consists of special, very fruity, fresh and somewhat cool "carbonic", aroma, is a high fermentation temperature. Fermentation temperature should not exceed 68F, othervise volatile aromatic compounds, born in CM, will be evaporized during fermentation.

 

[Ajmassa]

Yes, there are many different ways to do it. Sad, but i did not meet (virtually, on internet) not even one person, who tried to do not semi-carbonic maceration, but carbonic one- without adding fermenting must to the bottom of the vessel. So i know only theoretically, how it should be done. On most sources, carbonic maceration is being done in a bigger wineries, in a bigger vessels, where clusters on the bottom will crush unavoidably because of bigger weight beneath them. When doing this on a small scale, there are all possibilities to avoid free run juice on the bottom.
"I believe my use of enzymes + all those stems + my high abv nullified any CM benefits "
What could easily damage CM benefits, which also consists of special, very fruity, fresh and somewhat cool "carbonic", aroma, is a high fermentation temperature. Fermentation temperature should not exceed 68F, othervise volatile aromatic compounds, born in CM, will be evaporized during fermentation.

Oh yeah. I was fully aware that I had less than ideal circumstances for CM. I did it for the hell of it. More a curiosity. It was all about the inclusion of some stems so I just kept em whole cluster on the bottom. I don’t have ability to temp control anyway. Frankly I’m surprised to see how many people actually do. It’s not easy to control temps fermenting 300lbS worth of grapes.
What type of temp control system are you using?

 

[Forbidden Garden]

Oh yeah. I was fully aware that I had less than ideal circumstances for CM. I did it for the hell of it. More a curiosity. It was all about the inclusion of some stems so I just kept em whole cluster on the bottom. I don’t have ability to temp control anyway. Frankly I’m surprised to see how many people actually do. It’s not easy to control temps fermenting 300lbS worth of grapes.
What type of temp control system are you using?

I use manual temperature control When i crushed the grapes, i got 1014 oz of must. I use a bucket type plastic fermenters, with thermometers attached to them, so i can easily put them into cellar or cooler room, if temperature starts to rise a little bit during fermentation. In this time of a year i have got quite cool outside temperatures, so cooling does not require any efforts. It's better to choose yeast with working temperature on a cooler side, for post CM fermentation.