Starter question? Maybe an odd one

So my awesome wife just got me a stirplate. Yesterday I started a pack of wyeast 1007 for a german alt to be brewed Sunday.

Here’s the fun part it went fine and as expected as I’ve made a few starters with out the stirplate. I had a HVAC company out in the morning and had to work all evening. Apparently when the tech turned the ancient gas valve on something broke loose and we got a slight gas leak. I came home from work and smelled gas. I called the gas company and they came and advised turning the gas off. I’ll survive til morning and my starter is crashing in the fridge.

My question is should I dump and start over incase any of that gas and that terrible smell got pulled in through the foam stopper?

I think you are good. the yeast produces its own gas, so it would be pushing gas out not drawing it in.
any other opinions?

Agreed. From my understanding there is very little to no O2 intake while on the stirplate. What I understand about the stirplate is that it is a mechanism to keep the yeast in suspension. I’ve been reading about stirplates and shear stress and plan on making my next starter WITHOUT the stirplate.

If there’s no oxygen exchange, then why use a foam stopper instead of an airlock?

I’ve done it that way for the last 2 batches and have gotten results as least as good as using a stir plate. Here’s my story…http://www.experimentalbrew.com/blogs/d … new-tricks . While people are there, read some of the posts by S. Cerevisiae.

Thanks guys. That was my thinking as well. So if the stirplate doesn’t actually pull in a lot of oxygen would adding some pure O2 from the airstone before be a good idea? Or am I crazy in thinking that there is a time frame where it switches from pulling air in vs pushing CO2 out?

Deadeye, and Chop, read the above referenced article.

I’ve done it that way for the last 2 batches and have gotten results as least as good as using a stir plate. Here’s my story…http://www.experimentalbrew.com/blogs/d … new-tricks . While people are there, read some of the posts by S. Cerevisiae.[/quote]
Denny, I just got the same media bottle and plan on brewing next weekend. I’m gonna give that method a shot!

I’ve done it that way for the last 2 batches and have gotten results as least as good as using a stir plate. Here’s my story…http://www.experimentalbrew.com/blogs/d … new-tricks . While people are there, read some of the posts by S. Cerevisiae.[/quote]

I’ve never owned a stir plate and don’t have any interest in buying one. I’ve always just given the flask a swirl when I walk by it, and I always get airlock activity in the fermenter by 6 hours. Denny, I posted the following reply (found below in quotes) to your last post about your blog and didn’t get any responses. I understand that dry yeast is chock full of energy stores and is ready to work on the wort immediately once rehydrated. I’ve only been homebrewing for 2 1/2 years, but I always have a faster start to fermentation with a yeast starter (even if starting with dry yeast) than just rehydrating and pitching. I know this goes against conventional thought. This is just what I’m seeing:

“Great information, Denny. Thank you. This article prompted me to try a couple of different things with my yeast starter last week. If yeast counts double every 90 minutes, then that means even if I kill half my yeast by failing to properly rehydrate it first, I’ll be back to my original yeast count in only 90 minutes, correct? This time, I was planning two batches with US-05. I figured if I gave the yeast starter a few extra days to really build up the yeast count (i usually start the yeast starter 3 days before brew day but went 6 this time), I would just split it and pitch half the starter in each batch. I had airlock activity in 4 hours and had to switch to blow-off tubes (even with 6 gallon primaries) by 12 hours. This is compared to a rehydrated packet of yeast on brew day that I typically see no activity for 16 to 24 hours. I know this is not using the scientific method as I wasn’t doing 2 identical batches with one pitched with rehydrated yeast and one with a starter, but it does support the idea that you can get a shorter lag time even with a dry yeast starter. I also think rehydrating yeast is a waste of time. Besides, if I kill the weaker yeast cells by failing to rehydrate and aggressively propogate the strong ones in a starter, didn’t I just invoke Darwinism and have a healthier and stronger population of yeast going into the wort? Thoughts?”

There’s definitely a benefit to adding oxygen to your starter, in that the yeast will reproduce much more quickly and achieve higher cell densities. Whether you use an airstone or just shake the heck out of your starter is up to you, but you’ll end up with more cells if there is oxygen available prior to anaerobic fermentation. So yes, there is a timeframe in which the yeast will use up oxygen inside the vessel or passing through a foam stopper (provided there’s a means for it to get into the wort), and switch to producing CO2.

For the record, I’ve never used a foam stopper - my comment above was somewhat loaded. In theory it should allow more oxygen into your vessel, which makes it available to the yeast provided it can get into the wort (shaken or stirred), but it doesn’t do any good once CO2 starts building up in the vessel… might as well just use an airlock. I’ve been doing the same thing that Denny posted above - about a 1-liter starter in a large jug with airlock, shake it up really good from the start, and let it go. Shake it again whenever I walk by it.

I’ve never owned a stir plate and don’t have any interest in buying one. I’ve always just given the flask a swirl when I walk by it, and I always get airlock activity in the fermenter by 6 hours. Denny, I posted the following reply (found below in quotes) to your last post about your blog and didn’t get any responses. I understand that dry yeast is chock full of energy stores and is ready to work on the wort immediately once rehydrated. I’ve only been homebrewing for 2 1/2 years, but I always have a faster start to fermentation with a yeast starter (even if starting with dry yeast) than just rehydrating and pitching. I know this goes against conventional thought. This is just what I’m seeing:

“Great information, Denny. Thank you. This article prompted me to try a couple of different things with my yeast starter last week. If yeast counts double every 90 minutes, then that means even if I kill half my yeast by failing to properly rehydrate it first, I’ll be back to my original yeast count in only 90 minutes, correct? This time, I was planning two batches with US-05. I figured if I gave the yeast starter a few extra days to really build up the yeast count (i usually start the yeast starter 3 days before brew day but went 6 this time), I would just split it and pitch half the starter in each batch. I had airlock activity in 4 hours and had to switch to blow-off tubes (even with 6 gallon primaries) by 12 hours. This is compared to a rehydrated packet of yeast on brew day that I typically see no activity for 16 to 24 hours. I know this is not using the scientific method as I wasn’t doing 2 identical batches with one pitched with rehydrated yeast and one with a starter, but it does support the idea that you can get a shorter lag time even with a dry yeast starter. I also think rehydrating yeast is a waste of time. Besides, if I kill the weaker yeast cells by failing to rehydrate and aggressively propogate the strong ones in a starter, didn’t I just invoke Darwinism and have a healthier and stronger population of yeast going into the wort? Thoughts?”[/quote]

One thing I think you;re doing is overvaluing a fast start. There’s really no difference between a 2 hour start and a 2 day start if your sanitation is good. I don’t think there’s any value to killking the weaker cells, if indeed that’s what’s happening. Was the date code for both packs of yeast the same?

I agree with the importance of sanitation, and I believe I am very serious about sanitation, but I see a yeast starter as cheap insurance. I am very risk averse. If I just spent $30 to $40 on ingredients and other supplies and 4 to 5 hours of my time, I certainly am not going to be willing to lose a batch due to infection. Nobody is perfect with sanitation, and sooner or later, everybody gets a contaminated batch. As you stated in your blog, bacteria grows so much faster than yeast. I know for a fact that some types of bacteria can double every 20 minutes. If my yeast took 2 days to get going and I got a contaminant in there during cooling or transferring the wort, the yeast doesn’t have a chance at overwhelming that bacterial infection. I haven’t had a contaminated batch or stuck fermentation yet, and I feel a fast start is another tool to tip the scales in the yeast’s favor. Besides, there is less need to aerate with these higher initial yeast counts, and aeration, if you’re not careful, can be a source of contamination. Of course, some aeration is always necessary.

  Yes, all US-05 with same code and dating and purchased at the same time.  It's not just this yeast.  I have alternated doing yeast starters or not on different types of dry yeast since I started brewing, and it always seems like I have a much faster start with the starter even if I rehydrate 2 packets of dry yeast and don't do a starter.  Yeast is getting more expensive too.  If I can take one packet of yeast and build it up to get 10 gallons of wort bubbling in 4 hours versus 2 packets of rehydrated yeast and see nothing for 16 hours, I've also saved some money right?  One cup of DME is a lot cheaper than yeast.  

 Denny, you said it yourself, think less and experiment more.  You can't disagree with the idea that doing a dry yeast starter was an experiment, especially one that flies in the face of conventional thinking, right?    :D

One last thought: I like using a starter to proof my yeast. If I see activity in the starter, I know my yeast is not dead and I’m pitching in my fermenter yeast that is guaranteed to work. On another thread today, posters are sharing stories of having to repitch 3 days later because their packet of yeast was dead. So we’re going to reopen an air locked fermenter and expose the wort to contaminants again? No thanks. I’m not taking that chance.