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Old 05-31-2006, 04:24 AM   #1
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It probably won't but.......

I am planning a bit of an experiment and thought I’d get some feedback. I am moving my tank in two weeks time and will start the experiment then.

The premise of the experiment is that yeast in an aerobic environment will still produce CO2, but not alcohol. It is the alcohol in our brews that kills the yeast and limits the life span of the brew. If you could find a way to aerate the brew it would last much longer and produce a much larger amount of c02 before the brew dies..... In theory anyway.

The problem with this of cause is that you will “water” down your c02 and combine it with huge amounts of oxygen. But what if you only pumped air in for say 5 minutes every hour and could keep it from entering you reactor chamber??

It will be easy enough to run a small (very,very small) airpump into the brew and keep it all airtight and just have a timer on the air pump. My DIY reaction chamber is a little different to others in that I use a power head venturi fitting to pump the c02 into the reactor so I don’t have my brew connected directly to it. Instead it bubbles into a small chamber on the lip of my tank (about the size of a PH tester vial) and is sucked out by the venturi from there.

This means that while the air pump is on the excess gas that can’t be picked up by the venturi will simply escape from the vial-chamber thingy. My reactor chamber is very,very efficient so any oxygen that is drawn it will be dissolved very quickly (This could be beneficial for the tank as well?? Maybe?)

In short I don’t think it will work, but my tank has been running really well for the last year and a half and I miss all the playing around with stuff. I think the biggest problem will be getting an airpump to work in a pressurised environment. A check valve on the pump will be needed to stop the brew being forced back into the airpump (Could get ugly)

As I said I’ll be moving the tank in 2 weeks(give or take) and will start the experiment after that. Will let you know how it goes.

Any thoughts??
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Old 05-31-2006, 04:47 AM   #2
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Quote:
The premise of the experiment is that yeast in an aerobic environment will still produce CO2, but not alcohol. It is the alcohol in our brews that kills the yeast and limits the life span of the brew. If you could find a way to aerate the brew it would last much longer and produce a much larger amount of c02 before the brew dies..... In theory anyway.
Please forgive my ignorance, but won't yeast + sugar -> alcohol + CO2 be true whether there's oxygenation or not? How will more O2 limit the alcohol output but still produce CO2?

I do not understand the chamber vial thingy. Is it like a gas separator bottle, where CO2 from the generator bubbles up from a submerged line? If excess O2 can escape, why can't CO2 escape with it?

I think it is a fine idea and interested in the results. I do not think you need safteys along the line assuming the diffusor is so efficient more bubbles don't matter, fwiw.
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Old 05-31-2006, 12:07 PM   #3
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I actually brew beer at home so i'll offer what I can about what I know about yeast and it's process.

Yeast actually doesn't require oxygen to process the sugar (to a point). It simply can process sugar easier with oxygen in the mixture but it will produce alchohol regardless. In brewing beer, good oxygenation before introduction of the yeast is recommended. Just before the yeast is added the wort is sloshed heavily to add oxygen to the wort. Ultimately, your yeast will only live as long as there is sugar in the water. In most cases, it will run out of sugar before it runs out of oxygen.

As an experiment make three identical batches of your CO2 mixture.

The first: prepare as you normally would, this is your control
The second: Aerate heavily before adding the yeast. This can be done simply by shaking the bottle vigorously or with an airstone for an hour or two.
The third: aerate as above, but also aerate by shaking once a day during the observation perido.

I would imagine you'll want to observe both the rate of CO2 production as well as the duration of CO2 production.

further reading:
some detailed information on yeast
http://www.howtobrew.com/section1/chapter6.html
you'll be interested in this part:
http://www.howtobrew.com/section1/chapter6-9.html


[edit]
You may wish to consider a 4th experiment. Prepare a yeast mixutre the same as your control, except used boiled water (cool before adding the yeast of course). This will have a lower level of oxygen than your control mixture. For purposes of producing CO2 rather than alchohol this may give you a longer fermentation without having an initial spike in CO2 production... just a thought

[/edit]
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Old 05-31-2006, 08:58 PM   #4
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Quote:
Originally Posted by czcz
Please forgive my ignorance, but won't yeast + sugar -> alcohol + CO2 be true whether there's oxygenation or not? How will more O2 limit the alcohol output but still produce CO2?

I do not understand the chamber vial thingy. Is it like a gas separator bottle, where CO2 from the generator bubbles up from a submerged line? If excess O2 can escape, why can't CO2 escape with it?
Yeast can work in two ways Aerobic (when oxygen is available) an Anaerobic(When no oxygen is available). In an aerobic enviroment yeast can burn sugar and oxygen and will not produce alcohol (Like in bread) in an anaerobic environment the yeast can only burn sugar and will produce Alcohol(Beer and Wine)

The vial thingy is a bit hard to explain but here goes. I have a piece of Under Gravel Filter Pipe (Clear pipe about 2cm diameter) that I have cut to about 5 cms long. It is siliconed to the lip of my tank (The small horizontal piece of glass that the lids sit on) and extends below the water line. I bubble the co2 into this and the power head venturi fitting sucks he c02 from here. It's open at the bottom and the water pressure traps the gas. When the C02 is pumped in it is sucked out by the venturi. If you had more gas then the venturi can suck (Like when the 02 is pumping) It will just overflow the vial and bubble to the surface.

Hope I've explained this well enough.

I have a diagram I did of my tank in paint when I was first designing the setup bit it's a bitmap so I can't post it. Will convert it and post it tonight.

[edit]have added the image, just follow the c02 line and you'll see what I'm talking about. It's pretty simple but about the best I could do with Paint[/edit]

Quote:
Originally Posted by BillyZ
Yeast actually doesn't require oxygen to process the sugar (to a point). It simply can process sugar easier with oxygen in the mixture but it will produce alchohol regardless. In brewing beer, good oxygenation before introduction of the yeast is recommended. Just before the yeast is added the wort is sloshed heavily to add oxygen to the wort. Ultimately, your yeast will only live as long as there is sugar in the water. In most cases, it will run out of sugar before it runs out of oxygen.
apparently not- As above it's the difference between bread and beer. In a bread mix the yeast has all the o2 it needs so produces no alcohol. In beer the oxygen is depleted very quickly and so alcohol is produced. I am not sure if this is acutally true but I have heard this from many sources when I investigating different yeast strains - Am interested to see if it works!!!


Quote:
Originally Posted by BillyZ
The first: prepare as you normally would, this is your control
The second: Aerate heavily before adding the yeast. This can be done simply by shaking the bottle vigorously or with an airstone for an hour or two.
The third: aerate as above, but also aerate by shaking once a day during the observation perido.
Great idea - The only problem is that with '3' shaking will not aerate - c02 is heavier than o2 and all the o2 is pushed out of the system very quickly. Shaking the bottle will only increase the c02 level of the brew (If that's possible)

Thanks for the links though!!!!! Will have a look at these to see if can clear this up for me.
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Old 06-01-2006, 10:25 AM   #5
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Quote:
Originally Posted by SkullJug
apparently not- As above it's the difference between bread and beer. In a bread mix the yeast has all the o2 it needs so produces no alcohol. In beer the oxygen is depleted very quickly and so alcohol is produced. I am not sure if this is acutally true but I have heard this from many sources when I investigating different yeast strains - Am interested to see if it works!!!
Well yes and no. I've done some more reading myself and according to some of that reading (links to follow) I also see statements that suggest the production of alchohol is retarded when there is a high level of disolved oxygen. So on that point I stand corrected. However, the reading I've done also states the alchohol is still produced, just in smaller amounts. I think you would want, to some degree, to minimize the amount of oxygen in your co2 brew. The reason being is this passage;

Yeast can do all this with or without oxygen, but using oxygen makes the processes easier for the cell. Yeast use oxygen in the biosynthesis of the compounds that make up their cell membranes that allow them to process sugars for food and grow. Being able to process food and grow more efficiently allows them to reproduce more effectively also. Without oxygen, yeast cannot reproduce as fast.
(from http://www.howtobrew.com/section1/chapter6-9.html)

From that I draw the conclusion that the purpose of aerating it is to allow the yeast to reproduce to a high volume community to allow for a faster fermentation. Given that your goal is to stabalize and prolong the fermentation process therefore getting more use out of each batch of co2 brew then you wouldn't want this initial burst of population growth. (right?) I think the best way to tell what will get the most and stable co2 production would be to experiment with multiple batches as suggested above.

Quote:
Great idea - The only problem is that with '3' shaking will not aerate - c02 is heavier than o2 and all the o2 is pushed out of the system very quickly. Shaking the bottle will only increase the c02 level of the brew (If that's possible)
Good catch. I think the third test is important though as it is what you're proposing in essence, correct? Perhaps removing the cap to the bottle and using an empty turkey baster to blow fresh air into the bottle before shaking?


Links:
http://www.preparedpantry.com/index....=Custom&ID=173
As the yeast feeds on the sugar, it creates two digestive byproducts—alcohol (ethanol) and carbon dioxide. The carbon dioxide is what leavens the bread—carbon dioxide gases filter through the dough creating loft. The alcohol is evaporated in baking.

http://www.chymist.com/yeast.pdf
In the presence of oxygen, such as in the early stages of fermentation, the yeast metabolizes the sugars to essentially carbon dioxide and water with little alcohol formation. This is why there is little or no alcohol content in breads and naturally carbonated soft drinks.

http://www.preparedpantry.com/howyeastworks.htm
As the yeast cells feed, they expel carbon dioxide and alcohol. The carbon dioxide gas rises through the bread dough and is captured by the gluten structure in the dough to form air cells. The alcohol and other excretions impart a “yeasty” flavor to the dough. Master bread bakers manipulate the ratio of carbon dioxide to alcohol—usually with temperature and acidity--to control the rise time and the flavors in the breads.
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Old 06-01-2006, 04:41 PM   #6
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Your vial/venturii thing is cool. Very clever. But with the O2 generation a straight connector to the venturii input of the powerhead should still work without losing CO2.

(Any CO2 that bubbles out the vial will of course skew the results of your oxygenation of yeast, since presumably you'll be measuring effectiveness by deriving dissolved CO2.)

Just a thought.
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Old 06-02-2006, 01:03 AM   #7
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Quote:
Originally Posted by BillyZ

Yeast can do all this with or without oxygen, but using oxygen makes the processes easier for the cell. Yeast use oxygen in the biosynthesis of the compounds that make up their cell membranes that allow them to process sugars for food and grow. Being able to process food and grow more efficiently allows them to reproduce more effectively also. Without oxygen, yeast cannot reproduce as fast.
(from http://www.howtobrew.com/section1/chapter6-9.html)

From that I draw the conclusion that the purpose of aerating it is to allow the yeast to reproduce to a high volume community to allow for a faster fermentation. Given that your goal is to stabalize and prolong the fermentation process therefore getting more use out of each batch of co2 brew then you wouldn't want this initial burst of population growth. (right?)
Bugger!!!! Your right!!! I'll mull this over and post back later on. I'm still going ahead with the experiment though : >

Thanks for your help BillyZ
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CZCZ your right on the money - I have drawn up some plans and ran them past a friend of mine who is a hydraulics engineer. He's not a tank guy but is pretty good at seeing potential problems in my little tinkerings. I think I can mix it e.t.c no problems. But as you said, measuring the success will be difficult.

Basically I am just going to set it up with a control next to it and see which one lasts the longest. I can also grab one of those beer-alcohol-measurey-jiggers (??Hydrometer?? maybe?) to see if the alchohol level in the expired brews is higher in the control.

If it runs for six months I'll declare it a success ; ) (And probably get a species off Pleco named after me - Soon you'll all have a little SkullJug swimming around your tanks.

I am using the move as an oppurtunity to build a website for my tank and will include a ful llist of photos of the experiment - As I said give me a month or two and I'll have some results.

Quote:
Originally Posted by czcz
Your vial/venturii thing is cool. Very clever. But with the O2 generation a straight connector to the venturii input of the powerhead should still work without losing CO2.
I can't hook it up directly - Because I am using suction rather than the pressure that the brew creates there is too much risk of it compressing the bottle and sucking the brew into the tank!!!!! I didn't design the Vial-Thingy (Got to think of a better name) for this experiment - It just happens to be useful.
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Old 06-02-2006, 06:02 AM   #8
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Just a fwiw, I had that same concern with the venturii effect, but as long as the mix is producing gas it works fine, in my setups at least. Have been doing it this way since late last year.

Certainly better safe than sorry, of course.
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Old 06-02-2006, 11:04 AM   #9
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Quote:
Originally Posted by SkullJug
Basically I am just going to set it up with a control next to it and see which one lasts the longest. I can also grab one of those beer-alcohol-measurey-jiggers (??Hydrometer?? maybe?) to see if the alchohol level in the expired brews is higher in the control.
To accurately measure the alcohol level you'll need to take an accurate measurement of the specific gravity with a hydrometer both before and after.

OG = Original Gravity
FG = Final Gravity
DG = Differential Gravity
AM = % Alcohol by Mass
AV = % Alcohol by Volume

DG = OG - FG

AM = ((DG * 1.05)/FG)*100

AV = AM/.79

The hydrometer method isn't 100% accurate but is "close enough" for home use. An explanation can be found here:
http://science.howstuffworks.com/question532.htm
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