Possible experiment

[Belzicore]

Shout out to any engineering or chemistry majors who also brew

My question was, what would happen if you would chain the co2 output of one fermentating batch into the fluid of another? Doing this in series so that each new container has more co2 bubbles flowing through it than the last.

What effects do you think this would have on the:
-speed of the fermentation process
-final abv
-flavor of the brew

 

[BernardSmith]

Neither an engineer nor a chemist, but a social scientist. You normally want to remove CO2 from a batch a) to reduce physical stress on the yeast (pressure of the gas on the cells) and b) to reduce causes of a drop in pH and so reduce chemical stress on the yeast (CO2 can become carbonic acid in solution). Your "experiment" is then designed to increase stress on the yeast. I see obvious downsides to stressing yeast. What are the benefits of stressing yeast with CO2?

 

[Belzicore]

My hope was that by having the bubbles aggravate the stagnant bottom layer of yeast, I could keep them working for longer, thus speeding up the fermentation process. That and I've noticed toward the end of my fermentation cycles, I would often have to shake the container a little to get it to start bubbling again. I was hoping that the bubbles from the other containers could help do that.

Note that at the end of the series I would have a regular air lock so as to keep a relatively low pressure

 

[BernardSmith]

Aha.. Interesting.. A couple of thoughts: I wonder if when you shake the fermenter you are simply providing enough energy to the saturated CO2 to allow it to gather more easily and then get released from the fermenter (much like when you shake a can of soda and then open it) rather than adding anything to the fermentation process itself (does the SG drop?) Stirring to remove CO2 is what mead makers routinely do throughout active fermentation.
The "stagnant bottom layer" may not be so "stagnant" though it may contain dead yeast cells that undergo autolysis allowing their insides to become "fodder" for the living cells and allowing other compounds to bleed into your wine to add more complexity to the flavors. But again, stirring during active fermentation ensures that yeast cells that tend to flocculate too quickly (compared to the mean rate) and so fall to the bottom while still potentially very active are encouraged to stay afloat and so are less subject to being buried under the weight of other particulate matter dropping out of solution where that weight is enough to rupture cell walls allowing the insides to become outside.

 

[Belzicore]

All of your comments make alot of sense, and lead me to pursue my experiment with even more fervor. The increase in bubbles will help to remove co2 from each consecutive fermentation chamber, and if I plave the tube low enough it would essentially auto stir each new iteration.

When I do the experiment I wanted to take an abv rating each month, to see if there is any noticable change in the fermentation speed. Depending on my results I can tweak the overall design of the new fermentation vessel.

Any other comments/concerns you would like to make?

 

[crushday]

My two cents...but a question first: Why speed up the fermentation? Isn't it a palatable fact that a slower fermentation produces a better wine? I'm certain that shaking the fermentor isn't agitating or even aggravating the yeast, just releasing the suspended CO2.

All of my questions and certainties aside, you should throw yourself headlong into your experiment. Then, post your results as we are all interested. However, you/we won't know the fruition of your efforts for 24 months. But, I'm sticking around. So...

And, post pictures. That would be amazing.

 

[sour_grapes]

Also wondering why you would want to speed up fermentation?

Okay, I may not be an engineer or a chemist, but I am perplexed by your thesis here: You think that if you expose a solution that is saturated with CO2 to a stream of gaseous CO2, somehow you will help remove the CO2 from your solution? Color me skeptical.

 

[cmason1957]

And here I am always trying to slow down fermentation so that it might last for 10-14 days. Generally cooler temps help a bunch with that. As for what you are suggesting, wouldn't just stirring it be a whole heck of a lot easier?

 

[Rice_Guy]

All of your comments make alot of sense, and lead me to pursue my experiment with even more fervor. The increase in bubbles will help to remove co2 from each consecutive fermentation chamber, and if I plave the tube low enough it would essentially auto stir each new iteration.
When I do the experiment I wanted to take an abv rating each month, to see if there is any noticable change in the fermentation speed. Depending on my results I can tweak the overall design of the new fermentation vessel.
Any other comments/concerns you would like to make?

A few guesses:
* in essence you are saying what is the effect of running a larger fermentor? , , If you daisy chained five 5 gallon carboys you would be only running 25 gallons, if you chained ten it is only 50 gallons, not a lot when a small winery may run 500 and a big winery 10,000 gallons per tank.

* what do yeast need?
1) In growth phase they need oxygen for cell growth— If you were out of the primary, the growth phase is done and it is not an issue, yeast will have started to do anaerobic metabolism, if they have not gone through cell reproduction the fermentation would be significantly limited and I wouldn’t be surprised if it got stuck.
2) nutrition—- the assumption on the thought experiment is that all carboys are managed to start with equal nutrition since your goal is to produce quality wine. On a large fermentor agitation is provided to minimize disuniformity. In the scheme of things a 5 or a 50 gallon is small and I would not expect significant hot spots/ dead zones. ie. Maximum ABV is limited by the nutrient load at the start.
3) cooling —— yeast metabolism is exothermic and ALL large tanks have chill plates, combined with the mixing on #2 we strive to maintain within a few degrees of optimum. Yeast will die above 35 ( worst case like power failure) and have started to slow down at 30C. The larger tanks are basically limited by heat production, a chill plate will ice up if the mixing isn’t enough, ice acts as insulation so we can’t push the delta T too much. On daisy chained carboys the surface area is large therefore heat build up isn’t significant. To simulate this in your test you might insulate each carboy with 6 inches of fiberglass insulation. You will see that the fermentation is faster. If I run a 27.5C tank it will take about 3 days (and nutrition needs to be managed to keep it from smelling of SO2) where as a 10C fermentation is over 3 weeks , , , (but then those nasty fruit flavors hang in). ie rate is a function of temperature
4) respiration—- CO2 assuming that you don’t build up pressure the gas law defines how much CO2 is in the liquid. With a daisy chained set up there might be a slight increase in pressure, but not significant compared to a large tank, besides, glass and corks are not rated for 15 pounds of pressure and you would see catastrophic failure. A carboy with an airlock is at about 1 inch water column plus the height of the wine, , approximately 25 inches maximum pressure head, therefore not a lot of difference (the assumption is a single carboy actively fermenting is already saturated). To copy a commercial system I would run stainless steel soda carbonation tanks, connect with pipe or Tygon pressure tubing and then stack them to build up 7 to 10 feet of head. All of that said the gas law basically says that the amount of CO2 is linear with pressure therefore the top of the stack will have less dissolved gas than the bottom, the effect of which we try to minimize since #2 and #3 assume we have agitation running for the purpose of keeping the yeast alive. (a side note, yes some tanks are adgetated by bubbling nitrogen from the bottom). ie if CO2 builds up enough to make a difference get the mop and broom out
5) clearing the wine, a tall tank takes longer, especially since #2 and #3 have us mixing while fermentation is active.

All in all, , , industry works to create a situation whereby the fermentation runs as well as a 5 gallon carboy. The rate limiting factors keep forcing us to toss energy in to get rid of limits.

A neat vessel to tweek is continuous fermentation. —- I have seen a write up of a plug flow (long pipe) university lab set up where one could feed in juice on one end and pull wine out the other end. It was rated a few ml per hour and I think it pushed product in 12 or 24 hours. Sweet, , , when one is breeding and wants to estimate what a selection could do with 7 years in a traditional breeding program.

 

[winemanden]

If your No 1 (pumping) Brew developed Hydrogen sulphides, would it not be bad for your 2nd, 3rd etc wine. I wouldn't like the idea of bubbling through good wine!!

 

[Rice_Guy]

If your No 1 (pumping) Brew developed Hydrogen sulphides, would it not be bad for your 2nd, 3rd etc wine. I wouldn't like the idea of bubbling through good wine!!

The sulphide I have noted was on a test running high temp. Avoid stressing the yeast. Under healthy yeast conditions we should not bubble H2S through a carboy

There always is a risk of contamination carboy 1 to 2 to 3 etc. This is greater with more carboys pushing more CO2/ foam and I wondered about the risk of flooding the tubing, turning several grape varieties into a blended batch. (or mixing cranberry with peach)

I wouldn’t run the daisy chained test based on my guess of what could be gained, , , we will learn from the test by belzicore

 

[Belzicore]

Alright, Ignoring my terrible drawing, this was the idea. Since some were afraid of the buildup of sulfides, i wanted to clarify that the pressure would theoretically remain consistent throughout the fermenting process. I was going to be comparing this to a control batch of the same recipe. if you wanted to follow along i was going to be using (4) 2 liter soda bottles so that it roughly equals 2 gallons of mead. While i know plastic is far from the best choice, Im a scientist on a budget. ill post more pictures when i actually have the time and money to cook and prepare this batch.

 

[sour_grapes]

So what observables do you plan to test?

 

[Belzicore]

So what observables do you plan to test?

Test if there is any difference in taste.
Test to see if there is any difference in the total fermentation time.

side note, i wonder if there will be anything else that might be different.

 

[Belzicore]

So what observables do you plan to test?

Test if there is any difference in taste.
Test to see if there is any difference in the total fermentation time.

side note, i wonder if there will be anything else that might be different.

 

[Rice_Guy]

Test to see if there is any difference in the total fermentation time.

Temperature is the big driver, , , not likely to be different.

Test if there is any difference in taste.
side note, i wonder if there will be anything else that might be different.

,, A general trend, the smaller fermentation vessel (2 liter / half gallon) the more likely for oxidation to become evident. On the early stage of oxidation acetaldehyde forms. (guess = the flavor of acetaldehyde is harsh/ burning going down, have never ordered a chemical sample sooooo am guessing) As long as CO2 is being actively formed the system is anaerobic therefore secondary is not likely to be different. The question is how much headspace per liter of wine on third break? etc
,, Soda probably takes a #2 cork. #2 cork with two holes is rare, available in one out of ten stores. A laboratory cork borer is basically a brass tube which is sharpened on one end and handle on other.
,, The pressure head will be about 14 inches of water column which is less than a 5 or 7 gallon carboy
,, Cheap straight tubing, you can heat 1/4 inch polyethylene coiled tubing with a propane torch (or gas stove if the wife agrees) to take the bend out or make the bend at the cork a sharper one. American Scientific in Chicago stocks glass lab tubing. Didn’t catch which market you are in.

Good luck on the test

 

[stickman]

The last vessel in line will have significantly more co2 passing through on a volume basis, compared to being fermented by itself, so I would expect certain aromatics might be blown off.

 

[Belzicore]

Temperature is the big driver, , , not likely to be different.

,, A general trend, the smaller fermentation vessel (2 liter / half gallon) the more likely for oxidation to become evident. On the early stage of oxidation acetaldehyde forms. (guess = the flavor of acetaldehyde is harsh/ burning going down, have never ordered a chemical sample sooooo am guessing) As long as CO2 is being actively formed the system is anaerobic therefore secondary is not likely to be different. The question is how much headspace per liter of wine on third break? etc
,, Soda probably takes a #2 cork. #2 cork with two holes is rare, available in one out of ten stores. A laboratory cork borer is basically a brass tube which is sharpened on one end and handle on other.
,, The pressure head will be about 14 inches of water column which is less than a 5 or 7 gallon carboy
,, Cheap straight tubing, you can heat 1/4 inch polyethylene coiled tubing with a propane torch (or gas stove if the wife agrees) to take the bend out or make the bend at the cork a sharper one. American Scientific in Chicago stocks glass lab tubing. Didn’t catch which market you are in.

Good luck on the test

I acknowledge that you are trying to help with the experiment, but could you simplify what you said? particulalry what i underlined.

as for the method im getting the tubing from one container to the next, im just going to use simple plastic tubing. this experiment is meant to be very low cost.

 

[Rice_Guy]

I acknowledge that you are trying to help with the experiment, but could you simplify what you said? particulalry what i underlined.t.

I have sent you my phone no to talk you through "dry lab" what I would expect from your test procedure.
brief summary: From my my experience, 6 liters of wine isn't a lot, the variables that I expect to dominate are related to a small volume test.