Yeast starter - Airlock or foil?

Hey all - I just did my first yeast starter last night - been just dumping the vial from my LHBS into the fermenter with decent results until now. I've read many posts about Yeast starters and the main question is should I use an airlock or sanitized foil? I used foil on the one last night..

Personally, I use a foam stopper. It allows oxygen in, but nothing bad. Since oxygen is helpful for yeast growth, it works really well. Airlocks don't allow oxygen in, so I don't see much point in using one, except to see CO2 escaping, which is sorta silly. I've also used the tinfoil method, and it works pretty well.

+1 on tinfoil, but I just picked up some foam stoppers for my 2000 ml flask.

I used an airlock until I got a stirplate from stirstarters, now I use foil, I am constantly acquiring new equipment, almost weekly, lol

I use foil too. Never a problem. Knock on wood.

Another vote for foil...

+1 on foil, but this foam stopper thing is sounding good. Any links to foam stoppers?

There has been a lot of discussion on here about this. As far as I can tell, the best solution is just foil. An airlock is essentially a one way valve that lest the CO2 out, but no O2 in. At least with foil there can be some diffusion of O2 in.

I have a 100% success rate using foil. Fold it to a 3x3 or so square, spray it with Starsan, fold it loosely over the top and you are good to go. Cheap & effective. Montanaandy

BioBeing said:

There has been a lot of discussion on here about this. As far as I can tell, the best solution is just foil. An airlock is essentially a one way valve that lest the CO2 out, but no O2 in. At least with foil there can be some diffusion of O2 in.

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Right, and foam stoppers let oxygen in but provide an essentially impenetrable barrier for bad stuff, and they also allow CO2 to escape. Seriously, they're like $1 each, even cheaper in some places. For my money, they're much better than tinfoil. The only downside is that if you build too big or too vigorous a starter for the container the starter is in, the krausen can potentially get in it, and either push it out or dry it out. The stopper can then get stuck in the neck of the flask. I know because this has happened to me.


Anyway, here's what I'm talking about:
http://www.northernbrewer.com/default/foam-stopper-35-45mm.html
http://www.northernbrewer.com/default/foam-stopper-46-50mm.html

"foam stoppers let oxygen in but provide an essentially impenetrable barrier for bad stuff, and they also allow CO2 to escape"

How so? Everything that I have ready (and I have read a great deal on this) recommends using foil and indicates that the ability of bacteria to enter is negated by the escaping CO2 which provides a fairly sterile environment. Again, I base my statements on personal experience and I have had a 100% success rate on each starter using foil. Believe me if foil did not work I would switch to something else but it works great.

I asked my LHBS guy who has been in business for 30 years why he does not carry the foam stoppers and he indicated that he ran into sanitation issues with them when he did carry them so he stopped carrying them. It is pretty common for a starter to foam up past the neck of the flask and if the foam stopper is saturated with wort it would become a potential breeding ground for bacteria. Montanaandy

Well, actually we used to use foam stoppers in the lab for bacterial growth. I have nothing against them, but foil is just generally more readily available.

Montanaandy said:

"foam stoppers let oxygen in but provide an essentially impenetrable barrier for bad stuff, and they also allow CO2 to escape"

How so? Everything that I have ready (and I have read a great deal on this) recommends using foil and indicates that the ability of bacteria to enter is negated by the escaping CO2 which provides a fairly sterile environment. Again, I base my statements on personal experience and I have had a 100% success rate on each starter using foil. Believe me if foil did not work I would switch to something else but it works great.

I asked my LHBS guy who has been in business for 30 years why he does not carry the foam stoppers and he indicated that he ran into sanitation issues with them when he did carry them so he stopped carrying them. It is pretty common for a starter to foam up past the neck of the flask and if the foam stopper is saturated with wort it would become a potential breeding ground for bacteria. Montanaandy

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Like I said, they're not always a perfect solution, but they're what I personally prefer. I never said tinfoil didn't work. I'm not sure why they would be hard to sanitize - you can either dunk them in sanitizer, or just boil them in the neck of the flask.

As with everything in brewing, there are a million ways to do everything

foam stopper all the way.. but they aren't for beakers, etc.

+1 on foil.

I must be a hobo.. i use paper towel to cover the top then put a rubber band on it to keep crap from falling in it but allowing O2 in and CO2 out

I've seen a coffee filter used as well. Bacteria don't have legs, they need to arrive on dust particles, so as long as you use something to keep dust out you are going to be fine.

Foil for me nowadays.

Mirilis said:

I must be a hobo.. i use paper towel to cover the top then put a rubber band on it to keep crap from falling in it but allowing O2 in and CO2 out

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My recent and very successful Trader Joes vintage ale yeast harvest used a paper towel and painters tape to hold it all together, and the yeast sediment looks perfect. Probably going to be freezing it this weekend!

Cheers

Lucas

I use foil

Thanks for all of the replies - It looks like I'll keep using foil...

I've been playing back and forth, but just recently learned I've been wasting my time as I've been making starters with 11.5g Dry yeast packets, and from what I read, it doesn't help generate more yeast.

BUT, I first ran the airlock which did NOT function well. I later used Tin Foil which worked but recently started using the form stopper and have seen an increase in the intensity of the beginning fermentation.

Again, I'm fairly new so it could just be the difference in types of beer I've been making but it seemed to me the starter was stronger with the foam stopper.

My 2pennies... Which aren't worth much.

I have just been using an orange carboy cap with an inline sanitary air filter attached....I will periodically push pure O2 through the filter to fill the head space....Works great for me

So, I just used tin foil on a starter for the first time, and I can now say that I do NOT recommend it. Prior to this, I had only ever used airlocks, and without an issue, but with my new stirplate I built, I didn't have a stopper that would fit in a 2L Erlenmeyer flask.

Tinfoil does let CO2 out, and air in - but you know what else it lets in? Fruit flies. So I found my nice 1.5L starter swirling around on my stirplate with a fruitfly doing the backstroke in the vortex.

This required me to take an extra trip to the LHBS and purchase more yeast for the sulfited mead that I couldn't just leave lying around, and while I was there I made sure to pick up a proper stopper as well. For those of you who are concerned about the "one-way valve" effect with an airlock, I recommend that you use an aeration stone and pre-oxygenate your starter with pure O2 like I do.

The coffee filter and rubber-band idea also sounds like a viable one to me, but it does remind me of that old experiment disproving "spontaneous generation":



I'm not saying that it will happen, but it could, and thats enough to discourage me from using anything but an airlock. Filled with cheap vodka, preferably.

We ordered a starter kit, came with the foam stopper. Worked pretty well on the first one, but it did get wet a couple times when I swirled the starter. Not sure how much contamination risk that causes, but it seems more convenient than foil.

Overpanic said:

So, I just used tin foil on a starter for the first time, and I can now say that I do NOT recommend it. Prior to this, I had only ever used airlocks, and without an issue, but with my new stirplate I built, I didn't have a stopper that would fit in a 2L Erlenmeyer flask.

Tinfoil does let CO2 out, and air in - but you know what else it lets in? Fruit flies. So I found my nice 1.5L starter swirling around on my stirplate with a fruitfly doing the backstroke in the vortex.

This required me to take an extra trip to the LHBS and purchase more yeast for the sulfited mead that I couldn't just leave lying around, and while I was there I made sure to pick up a proper stopper as well. For those of you who are concerned about the "one-way valve" effect with an airlock, I recommend that you use an aeration stone and pre-oxygenate your starter with pure O2 like I do.

The coffee filter and rubber-band idea also sounds like a viable one to me, but it does remind me of that old experiment disproving "spontaneous generation":

I'm not saying that it will happen, but it could, and thats enough to discourage me from using anything but an airlock. Filled with cheap vodka, preferably.

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Thanks for this! That really sucks but a good lesson for the rest of us. I just listened to a BN episode with the whites about head pressure on fermentation and I was going to use foil on my next brew instead of an airlock. Don't want a fruit fly beer. Going to try the cap with inline filter instead on the fermentor this time.

I used only foil until I had a fruitfly issue. Now I cut a piece of fabric from a paint strainer bag. I sanitize a rubber band, the fabric piece and a piece of foil. I attach the fabric to my flask with the rubber band and then cover it with the foil.

I've always used foil, and I've never had a fruit fly doing the back stroke in my starter. I see fruit flies in my house every now and then, but no issues yet.

Stauffbier said:

I've always used foil, and I've never had a fruit fly doing the back stroke in my starter. I see fruit flies in my house every now and then, but no issues yet.

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Me neither. I've been using the foil method since it first came into brewing consciousness on here 4 or more years ago. I've had much better starters and NEVER had a bugger in my starter, even when I've had them floating around.

If they're getting in, just maybe you're not crimping it tight enough around the rim or something.

+1 foil

Foil = Air Lock

So far I've been using bubble lock. I've found that out of 100 starters I make I inevitable find a fly/ant in the bubble lock in about 3% of them.

Basically I just want to know why a bubble lock isn't as good as an airlock. People say oxygen, but is there any science behind this? Sources?

Edit: Obviously yeast need oxygen to do their thing, but will 2 days in a sealed jar (bubble lock) vs a slightly sealed jar (tin foil/coffee filter) make any difference?

+1 foil for me (although I have never tried one of the foam stoppers).

One possible exception: I seem to recall hearing on a podcast (basic brewing or brewstrong), that you actually want an airlock for either brett or lacto, as oxygen is not their friend... haven't done a starter for either of those yet myself.

Montanaandy said:

I have a 100% success rate using foil. Fold it to a 3x3 or so square, spray it with Starsan, fold it loosely over the top and you are good to go. Cheap & effective. Montanaandy

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Same method same results here.

Foil = airlock. This idea that Oxygen will get into the starter when you use foil or foam smacks of homebrew myth. Considering that the yeast are giving off considerable CO2, that would tend to push any O2 right out. I suspect those in the "let oxygen in" camp have never checked or measured if it actually occurs, and if the O2 actually gets into the liquid.

If you really want more O2 into the liquid, you need to take active steps to (1) get O2 inside the jar, and (2) get that O2 into the liquid.

The reason you shake it or put it on a stir plate is to oxygenate it. If you use an airlock it kind of seems to defeat the purpose.

SpeedYellow said:

Foil = airlock. This idea that Oxygen will get into the starter when you use foil or foam smacks of homebrew myth.

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In fact I've NEVER seen anyone state this.

What WE DO SAY is the the tinfoil doesn't allow the ALREADY EXISTING OXYGEN which we put into the starter wort, to escape out the airlock, before it gets consumed by the yeast, as we want it to do. Not that more oxygen gets in. That what is in there doesn't get out.

Oxygen is used by yeast to produce the monounsaturated fatty acids that are used to build the cell walls and store energy. You don't use an airlock, because that is a one way mechanism - it allows co2 to escape without allowing anything back in. This defeats the purpose of a stir plate (which is aimed at continuous oxygenation).

Starters are meant to propagate yeast through the aerobic process, not through fermentation.

I use a crumpled up paper towel. I don’t know if it does any better than an airlock, but it’s convenient, cheap and easy.

I have struggled to reconcile the notion of a CO2 blanket with what I know about partial pressure of mixed gases. George Fix, in “Principles of Brewing” said that CO2 coming out of solution will initially stratify, but eventually gas diffusion will restore equilibrium. So it’s a race with CO2 floating out the air, even as it’s diffusing with the air. With the volumes of gas coming off, it should pretty well blast out the air, but as the reaction slows, the air will creep back in.

For example, when you bottle, there’s always going to be a little bit of air in the headspace. Eventually that air will go into solution according to the partial pressures of the nitrogen and oxygen when it ultimately equalizes.

The notion of a thin layer of CO2 keeping oxygen away is not right. In a practical sense the effect is similar. The volumes of CO2 in a fermenter will eliminate most of the oxygen. The airlock will (mostly) keep the air out.

Ultimately the question is “Does the air coming into the starter have any significant effect on the oxygen level of the wort?” My guess is no. Once the fermentation takes off, the air doesn’t have much of a chance.

Revvy said:

In fact I've NEVER seen anyone state this.

What WE DO SAY is the the tinfoil doesn't allow the ALREADY EXISTING OXYGEN which we put into the starter wort, to escape out the airlock, before it gets consumed by the yeast, as we want it to do. Not that more oxygen gets in. That what is in there doesn't get out.

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Several people in this thread alone said that they like foil or foam because it lets O2 in. My point is simply that using foil and making it good & tight as suggested in this thread (by you and others) is effectively the same thing as a bubbler airlock. Both work fine.

It sounds like you're saying that a bubbler airlock somehow encourages more O2 to leave the vessel as compared to tight foil. That makes no sense.

According to this article: http://www.maltosefalcons.com/tech/yeast-propagation-and-maintenance-principles-and-practices
using an airlock does indeed hinder yeast growth in a starter (cited from Ray Daniels in Figure 1). Take that for whatever you feel it's worth, but it does jibe with the commonly held theory.

If your crimping the foil down tightly then you're not going to allow much gas exchange. And keeping it kind of loose to allow gas exchange but keep out dust-borne bacteria could definitely allow a fruit fly infestation.

So how about an empty 3 piece airlock? That would seem to satisfy all the desired criteria. Of course you then have to have a stopper for the flask, if that's what you're using.