Erlenmeyer Flask or Mason jar
- Thread starter McMalty
- Start date
Help Support Homebrew Talk:
bovineblitz
Well-Known Member
I got lucky and my neighbor "accidentally" ordered an extra at work in an order for his lab. Then that extra one accidentally fell into his truck on the way homeI really need to bottle a 6'er and take down to him.
I got mine similarly. A neighboring lab was closing down and giving away their glassware. I took a bunch for the lab and a few thing for me!
I dislike this comment because it is very illogical. I am also going to say it is a myth. I will explain...
- O2 is used within hours of pitching the yeast they do not require "constant" O2. (This is taken from Wyeasts site)
- Just because it looks like a tornado does not mean it has a vacuum and/or suction to it. It is a rotation that is mostly isolated to the liquid.
- When the yeast party starts, they produce CO2 creating positive pressure inside the vessel. In other words the flow of gas is out not in.
- I use bungs and airlocks on all my starters on a stir plate or not, I have never had a starter NOT work. I have also never seen an airlock get "sucked down" by negative pressure inside the flask/vessle, ever.
- The stir plate is able to make more yeast because the stir bar keeps the yeast in suspension continually and has little to nothing to do with aeration past the 1st few minutes of it being started.
If I am wrong or off base I would love to have someone with hard data/proof to show me, other than what "someone else told me"...because all of my basic observations say differently...
bigbeergeek
Well-Known Member
One gallon Carlo Rossi bottle, FTW. I refuse to drop that much money so I can eliminate a single transfer (and a single pot) from my process. To each their own, as is always the case in this obsession -- er, I mean hobby.
Hex
Well-Known Member
p. 134 Yeast
I use a 1L, then a 2L, then a 1G tea jug. And for each of them I use a different pad under the vessel, because they all sit at a different height on my stirplate.
![Craft A Brew - Safale S-04 Dry Yeast - Fermentis - English Ale Dry Yeast - For English and American Ales and Hard Apple Ciders - Ingredients for Home Brewing - Beer Making Supplies - [1 Pack]](https://m.media-amazon.com/images/I/41fVGNh6JfL._SL500_.jpg)
Zamial said:
Chris White's book "Yeast" explains it pretty. Yeah, technically that's a bit like saying "someone else told me" I suppose, though the guy owns and operates a yeast lab that doesn't just produce the 100B-cell count-vials for homebrewers like us, but also produces huge volumes of yeast for commercial breweries as well (not to mention a whole host of other services). If only Jamil Z, or especially John Palmer, had said it, I'd take it with a grain of salt and pursue a better source, but this is the field Chris White is educated in, and continues to live and breathe every single day.
However, the book isn't online and I'm not about to copy a bunch of pages out on my phone. It also didn't include a section with the academic papers proving the various elements that are probably needed to convince you - spanning subjects such as microbiology, fluid dynamics, etc (but with all the references cited, he might very well have provided the sources). Though he does delve a fair bit into the "why"s of things.
That's the reason many people use foam stoppers (and precisely why home brew stores sell them) - to allow for 2-way gas exchange without letting in beer-spoiling microorganisms. The other reccomendation (by both Chris White and now, knowledgeable homebrewers in general) and also quite widely used, is to sanitize a piece of aluminum foil and loosely cover the opening. I don't know if you use the Mr. Malty pitching rate calculator (which is based on widely available experimental data), but if you don't have a stirplate, the next most effective method is "continuous aeration" with an aquarium pump.
If you want to keep using an airlock on your starter, be my guest. But it's bad advice for other people who might use internet forums as their primary or even sole source of information. At least pick up Chris White's book (and perhaps some other reference material as well) if you're going to make posts that have the potential to wrongly influence people. You don't have to blindly believe everything (or anything) he says, but at the very least, it's important to read it before you dismiss it.
ok, i hear you. so can anyone corroborate this, b/c i don't know which way is correct. Do you need constant oxygen like the other poster stated or can you use an airlock. An airlock makes more sense to me, seems like the only way to ensure bacteria doesn't get in
McMalty said:
Like I said in the post above, a foam stopper is the preferred method to allow oxygen in without allowing bacteria in, but a sanitized piece of aluminum foil loosely folded around the mouth of the flask will also work. Bacterial infection and the benefits of oxygen in yeast propagation, are two entirely separate matters.
TANSTAAFB
Well-Known Member
Bacteria and wild yeast can't crawl, they can only fall, so a sanitized piece of foil is sufficient to keep the wild things out and allow the exchange of oxygen and CO2.
Not sure why Zamial has a problem with this but I will continue to follow the advice of the experts in the field (e.g., Chris White) and the plethora of experienced homebrewers who use this technique. I highly recommend the book Yeast to anyone who desires a better understanding of how to increase the health, vitality, and viability of their yeast.
Billybrewer09
Well-Known Member
Ok guys..I am the one that posted about the yeast starter kit from Midwest....my question is why would they include a rubber stopper and air lock if it was not meant to be used..it even says in the directions to use them..FIW I don't use them I use the sanitized foil trick and the stopper and air lock on my 6.5 gal carboy
bovineblitz
Well-Known Member
The reason I prefer a foam stopper over foil is fruit flies. If your foil isn't tight, there's space for a fruit fly to get into your wort.. and fruit flies looove wort. I had a starter go bad because of this once. Temporarily I made the foil much tighter, and long term I picked up a foam stopper.
You have to keep it away from direct light tho, correct?
TANSTAAFB
Well-Known Member
Thanks for the heads up!!! One foam stopper on the shopping list and really tight foil until then...check
TANSTAAFB
Well-Known Member
Why? Light skunks hops, no hops in a starter. You need to protect beer fermenting in clear carboys and bottled beer by using dark brown bottles, but there is no issue with starters on the counter in broad daylight in a clear flask.
thegerm
Well-Known Member
You're just trying to make good yeast, not good beer. No need to worry about oxidation or esters or fusels or skunking or anything like that. Especially if you cool and decant the starter beer before you pitch the yeast.
Dont use the stopper and air lock for your starter. They have it in the kits because thats what everyone did in the 70's. Luckily with the advent of communication we have moved beyond those days and created a whole new set of problems.
Anyway- keep the airlock on the carboy and the starter covered with something else. As has been said, you are making yeast, not beer. I have made lots of yeast with media, fermcap and an aquarium pump. Works better actually.
I guess I just wanted to clarify my earlier posts a bit. I do not have a problem with the foil or the foam stoppers. I am sure they work well enough to grow a starter. I certainly am not recommending people use airlocks on their starters. (I also know that me saying an airlock is fine, is like screaming LIES!!! in a church because it goes against what we have been told/taught.) I was looking for the reason to not use an airlock.
The reason stated is for a gas exchange going into the Erlenmeyer flask which the airlock 100% stops from happening. I suspect the foam stopper will also inhibit gas exchange as it would require a positive pressure to move air through it. The reason that foil is used is because it is believed to allow gas exchange both ways and nasties only can fall down, not climb up, it is also cheap and just about every home has it on hand.
My question/issue/thoughts are based on MY observations and limited knowledge of how all these things tie together. I am certainly not a microbiologist or some yeast guru or even a physicist but this is how I believe things to work:
The stir plate creates a vortex. This vortex only effects the gas that is inside the vortex and just above the surface. This vortex will expose a large surface area of the wort to the O2 that is inside the flask. The yeast will use up all of the available oxygen within hours. At that point they will start to create CO2. When they start to create CO2 this will create positive pressure inside the flask. If there is positive pressure from inside the flask, I do not believe that there is any way short of an O2 stone, to allow O2 into the vessel. IDC if it is foil, foam or a breathable membrane. O2 can NOT get into naturally because the CO2 is coming out. (This is why open fermentation works...)
When I see some flawed logic I tend to question it. If we do not question things we will never learn. IMO if you cover the opening of your starter, you may as well use an airlock because no gas is getting in anyways. I am not trying to be right or wrong, I am trying to explain why I believe that "using an airlock on a starter being bad" is flawed logic, from my observations...
To comment on the foil over a non-stirplated starter, it is a much better choice than an airlock because you shake it whenever you walk by. Shaking a vessel full of liquid with an airlock on it is asking for a giant mess and an easy way for unwanted things to get into the starter.
I freely admit that I can be 100% wrong about this. I am looking for some hard evidence that the airlock is bad to use. This is like telling me sugar will only dissolve in tea when it is stirred clockwise. When I say that does not sound right to me, I would like a better answer than "X told me so" or "that is how we have done it for the last X years". I also am looking and having some trouble finding a real solid answer.
The reason stated is for a gas exchange going into the Erlenmeyer flask which the airlock 100% stops from happening. I suspect the foam stopper will also inhibit gas exchange as it would require a positive pressure to move air through it. The reason that foil is used is because it is believed to allow gas exchange both ways and nasties only can fall down, not climb up, it is also cheap and just about every home has it on hand.
My question/issue/thoughts are based on MY observations and limited knowledge of how all these things tie together. I am certainly not a microbiologist or some yeast guru or even a physicist but this is how I believe things to work:
The stir plate creates a vortex. This vortex only effects the gas that is inside the vortex and just above the surface. This vortex will expose a large surface area of the wort to the O2 that is inside the flask. The yeast will use up all of the available oxygen within hours. At that point they will start to create CO2. When they start to create CO2 this will create positive pressure inside the flask. If there is positive pressure from inside the flask, I do not believe that there is any way short of an O2 stone, to allow O2 into the vessel. IDC if it is foil, foam or a breathable membrane. O2 can NOT get into naturally because the CO2 is coming out. (This is why open fermentation works...)
When I see some flawed logic I tend to question it. If we do not question things we will never learn. IMO if you cover the opening of your starter, you may as well use an airlock because no gas is getting in anyways. I am not trying to be right or wrong, I am trying to explain why I believe that "using an airlock on a starter being bad" is flawed logic, from my observations...
To comment on the foil over a non-stirplated starter, it is a much better choice than an airlock because you shake it whenever you walk by. Shaking a vessel full of liquid with an airlock on it is asking for a giant mess and an easy way for unwanted things to get into the starter.
I freely admit that I can be 100% wrong about this. I am looking for some hard evidence that the airlock is bad to use. This is like telling me sugar will only dissolve in tea when it is stirred clockwise. When I say that does not sound right to me, I would like a better answer than "X told me so" or "that is how we have done it for the last X years". I also am looking and having some trouble finding a real solid answer.
JNye
Well-Known Member
We are talking about atoms of gas. The idea is if you have gas exchange out, you will have some coming in. Think of how an airlock works. It only burps when the pressuse is high enough. If you are using the loose foil then CO2 is constanly flowing out at atmospheric pressure. Gas is slowly flowing in and out freely at atmospheric pressure.
thegerm
Well-Known Member
A loose fitting top allows for an exchange of gases since it is by design not an impermeable barrier. Even if there is a higher partial pressure of co2, o2 will get in there and work it's way into the solution thanks to the constantly exchanging surface of the liquid caused by the vortex.
An airlock's purpose is twofold, to keep bugs out, but also to provide a single direction flow of gases and prevent oxidation during later fermentation.
Now some o2 can pass through the liquid in an airlock, but it's orders of magnitude less.
The experimentation that has been done by JZ was with loose fitting tops, not with airlocks. You can infer the difference in having a free constant exchange of gases by using his calculator and viewing the difference in final cell count between a simple starter and stir plate starter. I think using an airlock would give you the same results as a simple starter because your airlock would be mostly blocking the inflow of o2.
Your starter will obviously "work" either way. One way will give you a much higher cell count however.
An airlock's purpose is twofold, to keep bugs out, but also to provide a single direction flow of gases and prevent oxidation during later fermentation.
Now some o2 can pass through the liquid in an airlock, but it's orders of magnitude less.
The experimentation that has been done by JZ was with loose fitting tops, not with airlocks. You can infer the difference in having a free constant exchange of gases by using his calculator and viewing the difference in final cell count between a simple starter and stir plate starter. I think using an airlock would give you the same results as a simple starter because your airlock would be mostly blocking the inflow of o2.
Your starter will obviously "work" either way. One way will give you a much higher cell count however.
Foam stoppers actually do allow for gas exchange. If that wasn't the case, at a minimum I should be hearing a "pop" when pulling it out, only to find an extremely carbonated starter, and at worst, the thing would keep flying out like a plugged-up airlock.
So there's a strong indication that at the very least, it permits gas exchange at a rate equal to or greater than the rate of CO2 generation by the yeast in a typical starter. The positive pressure therefore should be pretty minute, and should impair oxygen flow no more than with a loose aluminum foil cap or even an uncovered starter. I prefer to use the foam stopper because, while bacteria may not be able to maneuver around a foil cap, fruit flies certainly can. I used to make traps for them as a kid - with beer, no less - and it quickly became obvious that I needed to tape every possible seam down, because those guys can find their way through little holes and cracks that even seem too small for them.
I'd be interested to see if a foam stopper could handle a 5Gal batch without flying out though... it would definitely demonstrate that it is more than capable of handling both the CO2 outflow and much more than an equivalent inflow for any homebrew-sized starter.
I realize though that it still leaves the question of whether oxygen can even get past the tiny amount of positive pressure created by the constant CO2 generation. If some has access to some sort of O2 meter, it seems like an easy enough experiment.
However, if you're not just being stubborn and argumentative, I highly recommend you pick up Chris White's book, "Yeast." You can probably find it for about $10, and it's definitely a worthwhile read. I don't personally feel the need to second guess him on matters of yeast propagation anymore than I would have felt the need to debates Richard Feynman on a nuclear-physics related matter - not that I am comparing the two, as it's damn near impossible to even hold a dim candle to Feynman. But this is extremely simple science for Chris White, something so fundamental and so easily demonstrated to be wrong or right, that it almost seems like a waste of time to double-check him (and all his colleagues, competitors, and contemporaries) on this particular assertion. But if you disagree, he cites plenty of references in his book if you really need to review them, and also responds to emails from anyone (though it takes a week or two) if you're still not satisfied at that point.
So there's a strong indication that at the very least, it permits gas exchange at a rate equal to or greater than the rate of CO2 generation by the yeast in a typical starter. The positive pressure therefore should be pretty minute, and should impair oxygen flow no more than with a loose aluminum foil cap or even an uncovered starter. I prefer to use the foam stopper because, while bacteria may not be able to maneuver around a foil cap, fruit flies certainly can. I used to make traps for them as a kid - with beer, no less - and it quickly became obvious that I needed to tape every possible seam down, because those guys can find their way through little holes and cracks that even seem too small for them.
I'd be interested to see if a foam stopper could handle a 5Gal batch without flying out though... it would definitely demonstrate that it is more than capable of handling both the CO2 outflow and much more than an equivalent inflow for any homebrew-sized starter.
I realize though that it still leaves the question of whether oxygen can even get past the tiny amount of positive pressure created by the constant CO2 generation. If some has access to some sort of O2 meter, it seems like an easy enough experiment.
However, if you're not just being stubborn and argumentative, I highly recommend you pick up Chris White's book, "Yeast." You can probably find it for about $10, and it's definitely a worthwhile read. I don't personally feel the need to second guess him on matters of yeast propagation anymore than I would have felt the need to debates Richard Feynman on a nuclear-physics related matter - not that I am comparing the two, as it's damn near impossible to even hold a dim candle to Feynman. But this is extremely simple science for Chris White, something so fundamental and so easily demonstrated to be wrong or right, that it almost seems like a waste of time to double-check him (and all his colleagues, competitors, and contemporaries) on this particular assertion. But if you disagree, he cites plenty of references in his book if you really need to review them, and also responds to emails from anyone (though it takes a week or two) if you're still not satisfied at that point.
I agree that the foam will allow CO2 out with little to no problems, it is the in flow that I do not believe exists during the CO2 out gasing.
No, I am not being stubborn or combative. I am truly intrigued by this. I will more than likely see if I can get a loaner copy of that book. I also have some "lab people" I can ask that may hold a bit of greater input on the subject.
What I would really REALLY like to see is a time lapse video of a flask on + off a stir plate being filmed with a gas sensitive camera, so we can actually know if there is any in flow of air on any of these set ups. I do however seriously doubt I will ever have access to anything like this...I would not be shocked to learn that there was none on any of them.
No, I am not being stubborn or combative. I am truly intrigued by this. I will more than likely see if I can get a loaner copy of that book. I also have some "lab people" I can ask that may hold a bit of greater input on the subject.
What I would really REALLY like to see is a time lapse video of a flask on + off a stir plate being filmed with a gas sensitive camera, so we can actually know if there is any in flow of air on any of these set ups. I do however seriously doubt I will ever have access to anything like this...I would not be shocked to learn that there was none on any of them.
TANSTAAFB
Well-Known Member
Also not being argumentative, but if there is no O2 exchange then how do you explain the empirically proven results of twice the yeast growth in a stir-plate starter over a non-stirred starter? It seems to me that O2 is the only independent variable that is being manipulated. Thoughts? What else could account for the significantly greater growth?
TANSTAAFB said:
He seems to believe it's the fact that yeast is kept in suspension. Which is probably helpful, but it doesn't explain how continuous aeration with an aquarium pump is better than a repeatedly shaken starter.
I think I need to clarify again. I am not saying there is not any O2 exchange, I wholeheartedly, 100% believe there is but only at the very start. What I am saying is that the O2 is absorbed that is inside the flask and used by the yeast, then they start to create CO2. At that point there is no more "In flow" or "O2 transfer" because it can not enter the flask that is creating CO2 gas inside itself. A stirred starter will certainly have a greater O2 absorbing rate over a non-stired one while there is O2 inside of it...
It is this O2 rate at the start, as I mentioned above. Within a few hours the starter will use up the O2 inside itself and then the CO2 keeps any more O2 from entering. With a pump this changes things as you are introducing O2 but since the yeast is not kept in continuous suspension, you should get less cells than a stir plated starter but more cells than a shaken one.
BTW great discussion!
thegerm
Well-Known Member
It's just basic principles of diffusion, simplified further by the fact that starters are not under a pressure differential.
SpaceJunk
Active Member
In mushroom growing it is common to use Tyvek as a filter medium because it provides good two way gas exchange and can be autoclaved. It is secured on top of a flask for a liquid culture or placed over a mason jar and the ring screwed down over it for grain jars. The mailers that the post office uses are made out of Tyvek and is a good source for the material. Of course you are talking about much higher positive pressures so you may not want to secure the Tyvek too tightly.
Similar threads
