Occasional aeration in yeast starter

[Bokonon]

I haven't built a stir plate yet, but just today I was looking for something and came across my old X-10 home automation stuff. I've got an aquarium pump, hepa filter, and airstone already, and in previous batches I would leave the stone in the starter and plug in the pump every few hours for a few minutes. Well sometimes I would forget I had it plugged in for a few minutes so it would foam out the top.

So today I hooked the pump up to an appliance module and have it set to kick on for 2 minutes every 5 minutes. I'll see over the next few hours how the schedule is working, if it foams up too much I'll have to cut it down to a 1 minute duration or a 10 minute interval.

Not sure if anyone has tried something like this before but I thought I would throw it out there. I'm sure eventually I'll actually build a stir plate since I should have everything necessary (minus the stir bar), but I'll have to find the box that has all my electronic components in it from when I moved a while ago.

 

[Bokonon]

Ok quick update here. I've had this going for a few hours and I marked the outside of my container (I use a 1 gal growler) with a piece of masking tape to monitor the foam level. It's been increasing at a rate that within 8 hours or so it should likely come out the top, so I've cut it down to run every 10 minutes for 2 minutes.

If I'm not able to find any equilibrium before I go to bed I might just change it to run for a few minutes every 30-60 minutes so it doesn't blow out when I'm sleeping tonight

 

[Iordz]

I think that's a great idea. If you make a stir plate you could somehow incorporate this. That would really lead to great starters. Not only will you be continuously aerating but the yeast will be kept in suspension for the duration too.

 

[Bokonon]

Ok so 2 minute duration every 10 minutes seems to be the minimum thats possible. It made it through the night but I think theres some improvment that could be made. I've switched to a 3 minute duration every 10 minutes, and I'll report back with how this goes.

 

[Philip1993]

Ok so 2 minute duration every 10 minutes seems to be the minimum thats possible. It made it through the night but I think theres some improvment that could be made. I've switched to a 3 minute duration every 10 minutes, and I'll report back with how this goes.

If you've got any electronics skill, pair a 555 or 556 timer with a relay. That'll do just about about interval you want.

 

[Bokonon]

If you've got any electronics skill, pair a 555 or 556 timer with a relay. That'll do just about about interval you want.

When I said the minimum thats possible that wasn't what I really meant. I meant the maximum I would set and leave running overnight without my watchful eye. With the X-10 gear I can program events to happen on the minute, or if I don't have the unit programmed and just execute commands from my linux box then I can have it send events at any time (with about a delay of 1-1.5 seconds)

I've got the electronics skill to use a timer and relay to do this, but all my gear is in a box in a room that is filled with boxes from when we moved. I ran across the X-10 gear when I was looking for something else so I knew which box that was in (and it was towards the front of the room)

I'm not sure I'll have any way to know for sure how well this does, but using Jamil's pitching calculator I'm shooting for somewhere between "Simple with O2 at start" and "Continuous Aeration"

 

[ohad]

Wouldn’t this constant aeration of the starter make it into vinegar?
I did something similar, but much more basic method, a couple of days ago and the starter went sour. I'm a beginner to brewing in general, and even more so when it comes to starters, but isn't that a bad thing? Or do you pour out all the liquid from the starter and use only the sediments?

 

[ScubaSteve]

Seems like 2 or 3 minutes every 10 mins is quite a bit! You could have it come on for a few minutes every hour and be more than fine! Those diffusion stones can dissolve a LOT of oxygen in a short period of time, especially into a container as small as a 1 gal growler. Does your setup disrupt the wort enough to effectively "stir" it?

 

[Bokonon]

Seems like 2 or 3 minutes every 10 mins is quite a bit! You could have it come on for a few minutes every hour and be more than fine! Those diffusion stones can dissolve a LOT of oxygen in a short period of time, especially into a container as small as a 1 gal growler. Does your setup disrupt the wort enough to effectively "stir" it?

Unfortunately it doesn't quite stir it, so I've taken to doing what I did before I had the pump/stone and swirling it around every time I pass it by. Which amounts to at least 3 times a day but probably more like 5-6 times.

From the MrMalty pitching calculator help page

Continuous Aeration
Continuous aeration provides more oxygen for your starter and results in more yeast growth and better yeast health. This is usually done by continually pumping sterile filtered air into the starter via an aquarium pump. The pump continually adds air into the starter and the top of the starter is covered with aluminum foil.

In my setup if I would provide continuous aeration it would end up foaming out the top in no time. So I'm just trying to get it as close as possible to continuous aeration.

Using the pitching calculator with 5.75 gals at 1.070 it tells me I need:
w/ simple stater: 4.2L
w/ simple starter with O2 at start: 3.15L
w/ Intermittent shaking: 2.42L
w/ Continuous aeration: 2.1L
w/ stir plate: 1.58L

so I'm expecting levels between intermittent shaking and continuous aeration.

 

[Shockerengr]

Wouldn’t this constant aeration of the starter make it into vinegar?
I did something similar, but much more basic method, a couple of days ago and the starter went sour. I'm a beginner to brewing in general, and even more so when it comes to starters, but isn't that a bad thing? Or do you pour out all the liquid from the starter and use only the sediments?

aeration won't cause it to turn to vinegar, only bacteria will do that. add'l air in a starter is good because it encourages growth of the yeast. The HEPA filter is inline with the pump to keep bacteria from contaminating the starter

 

[raceskier]

I find the breathable stopper on the starter flask to produce great results. Allows CO2 out and air in, but filters fine enough to keep out the nasties. I don't risk contamination from the additional handling steps.

 

[ohad]

aeration won't cause it to turn to vinegar, only bacteria will do that.

so if my latests starter was a bit sour (I tasted it to try and see that its not infected) .... was it contaminated with bacteria? is there never an option of sourness in beer from yeast fermentation?