Comments on: Aeration and Yeast Starters http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/ I love blog. Fri, 27 Aug 2010 18:12:41 -0400 http://wordpress.org/?v=2.9.2 hourly 1 By: Increasing Cell Counts in Starters - Page 2 - Home Brew Forums http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-196 Increasing Cell Counts in Starters - Page 2 - Home Brew Forums Fri, 18 Jun 2010 15:39:01 +0000 http://seanterrill.com/?p=1399#comment-196 [...] I don't know if you've seen this; it's come up in a few other threads. Aeration and Yeast Starters Nowhere near a 4x increase, but clearly agitation/aeration works. __________________ Beer is [...] [...] I don't know if you've seen this; it's come up in a few other threads. Aeration and Yeast Starters Nowhere near a 4x increase, but clearly agitation/aeration works. __________________ Beer is [...]

]]> By: To Stir Plate or Not To Stir Plate? - Home Brew Forums http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-184 To Stir Plate or Not To Stir Plate? - Home Brew Forums Wed, 09 Jun 2010 16:22:48 +0000 http://seanterrill.com/?p=1399#comment-184 [...] shaking is almost as good as a stirplate, and that direct aeration is the best technique of all: Aeration and Yeast Starters Overall it seems that agitation doesn't do much in and of itself (for a low-gravity wort, anyway). [...] [...] shaking is almost as good as a stirplate, and that direct aeration is the best technique of all: Aeration and Yeast Starters Overall it seems that agitation doesn't do much in and of itself (for a low-gravity wort, anyway). [...]

]]> By: Stir Plates and Pitch Rates - Home Brew Forums http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-177 Stir Plates and Pitch Rates - Home Brew Forums Mon, 24 May 2010 16:52:27 +0000 http://seanterrill.com/?p=1399#comment-177 [...] http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/ I have some problems with the methodology, but more importantly according to the write up the stir plate version (see updates, the original experiment lacked a stir plate) resulted in substatially more yeast than the aerated version. The opposite of the claim in the OP. Does Sean Terril say different things in the podcast than he does on his blog? __________________ http://remilard.mybrute.com [...] [...] http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/ I have some problems with the methodology, but more importantly according to the write up the stir plate version (see updates, the original experiment lacked a stir plate) resulted in substatially more yeast than the aerated version. The opposite of the claim in the OP. Does Sean Terril say different things in the podcast than he does on his blog? __________________ http://remilard.mybrute.com [...]

]]> By: Build a Better Stirplate « SeanTerrill.com http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-153 Build a Better Stirplate « SeanTerrill.com Mon, 26 Apr 2010 05:35:48 +0000 http://seanterrill.com/?p=1399#comment-153 [...] (39) Popular PostsAeration and Yeast StartersYeast Ranching and YouWater, Water EverywhereGood Beer, Easy BeerYeast Pitching Rate ExperimentBM2K9 [...] [...] (39) Popular PostsAeration and Yeast StartersYeast Ranching and YouWater, Water EverywhereGood Beer, Easy BeerYeast Pitching Rate ExperimentBM2K9 [...]

]]> By: Tweets that mention Aeration and Yeast Starters « SeanTerrill.com -- Topsy.com http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-150 Tweets that mention Aeration and Yeast Starters « SeanTerrill.com -- Topsy.com Fri, 16 Apr 2010 02:22:00 +0000 http://seanterrill.com/?p=1399#comment-150 [...] This post was mentioned on Twitter by Andy Murphy. Andy Murphy said: Not using an airlock after reading this starter experiment - http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/ [...] [...] This post was mentioned on Twitter by Andy Murphy. Andy Murphy said: Not using an airlock after reading this starter experiment – http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/ [...]

]]> By: webmaster http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-148 webmaster Thu, 18 Mar 2010 21:44:02 +0000 http://seanterrill.com/?p=1399#comment-148 If you’re compensating for the alcohol, then yes, you’re calculating the real attenuation. 75% would be very high for anything except maybe light lagers – that would correspond to about 93% apparent attenuation, or a 1.050 beer attenuating down to 1.004. 75% apparent attenuation is probably a realistic average for ales (1.050 OG, 1.012 FG), but that’s only 61% real attenuation. If you’re compensating for the alcohol, then yes, you’re calculating the real attenuation. 75% would be very high for anything except maybe light lagers – that would correspond to about 93% apparent attenuation, or a 1.050 beer attenuating down to 1.004.

75% apparent attenuation is probably a realistic average for ales (1.050 OG, 1.012 FG), but that’s only 61% real attenuation.

]]> By: agenthucky http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-146 agenthucky Wed, 17 Mar 2010 17:30:19 +0000 http://seanterrill.com/?p=1399#comment-146 I believe I was referring to absolute attenuation. When I figure my FG, I take into account the error from the alcohol present. This would be actual attenuation, correct? If that is the case, is 55% normal? I stand by my average of 75%. I believe I was referring to absolute attenuation. When I figure my FG, I take into account the error from the alcohol present. This would be actual attenuation, correct? If that is the case, is 55% normal? I stand by my average of 75%.

]]> By: webmaster http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-145 webmaster Tue, 16 Mar 2010 15:42:08 +0000 http://seanterrill.com/?p=1399#comment-145 I think the <a href="http://www.byo.com/stories/wizard/article/section/121-mr-wizard/931-is-it-possible-to-aerate-your-yeast-too-much" class="bodylink" rel="nofollow">Mr. Wizard column</a> you're referencing deals primarily with pure oxygen infusion rather than aeration. The saturation point for O2 in water is about 8 ppm at STP, but using oxygen it's possible to super-saturate the wort. At that point you may run the risk of oxidizing the cell walls themselves, but my understanding is that the risk is minimal at normal O2 concentrations. For example, the commercial yeast libraries are grown up by using continuous aeration (<a href="http://www.danstaryeast.com/library/aeration-and-starter-versus-wort" class="bodylink" rel="nofollow">ref. Clayton Cone</a>), although they also propagate below 1.002 SG to avoid the Crabtree Effect. In my own brewery, I have several yeast strains that have been propagated for multiple generations from aerated starters, and still provide excellent (and more to the point, consistent) fermentation performance. I also believe that it's a good idea to minimize stress by propagating yeast from the starter rather than the fermenter, and that's actually my normal practice. I'm going to be posting a full writeup of my yeast handling procedures in the near future, as soon as I have a chance to take some better photographs. I think the Mr. Wizard column you’re referencing deals primarily with pure oxygen infusion rather than aeration. The saturation point for O2 in water is about 8 ppm at STP, but using oxygen it’s possible to super-saturate the wort. At that point you may run the risk of oxidizing the cell walls themselves, but my understanding is that the risk is minimal at normal O2 concentrations. For example, the commercial yeast libraries are grown up by using continuous aeration (ref. Clayton Cone), although they also propagate below 1.002 SG to avoid the Crabtree Effect.

In my own brewery, I have several yeast strains that have been propagated for multiple generations from aerated starters, and still provide excellent (and more to the point, consistent) fermentation performance. I also believe that it’s a good idea to minimize stress by propagating yeast from the starter rather than the fermenter, and that’s actually my normal practice. I’m going to be posting a full writeup of my yeast handling procedures in the near future, as soon as I have a chance to take some better photographs.

]]> By: webmaster http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-144 webmaster Tue, 16 Mar 2010 15:40:43 +0000 http://seanterrill.com/?p=1399#comment-144 Three of the slurries (one sucrose, two DME) were allowed to compact fully, and I calculated the intermediate density by assuming that the fully compacted columns would have the density of 4.5 billion/mL cited by Jamil. All three, on a volumetric basis, compacted by the same amount (plus or minus 1 mL). Three of the slurries (one sucrose, two DME) were allowed to compact fully, and I calculated the intermediate density by assuming that the fully compacted columns would have the density of 4.5 billion/mL cited by Jamil. All three, on a volumetric basis, compacted by the same amount (plus or minus 1 mL).

]]> By: Fred L. Johnson http://seanterrill.com/2010/01/14/aeration-and-yeast-starters/comment-page-1/#comment-143 Fred L. Johnson Tue, 16 Mar 2010 11:13:15 +0000 http://seanterrill.com/?p=1399#comment-143 Regarding the method of estimating yeast cell counts from the volume of the sediment, I was referring to the variable density of cells within the column of the sediment. Certainly the cell density is higher at the bottom of the column than at the top, and I've not seen data to confirm that the average cell count per milliliter is the same for various volumes of semi-packed cells. WIthout validation of the method, one cannot reliably compare the measured values from one experiment to another in a strictly mathematical way. Regarding the method of estimating yeast cell counts from the volume of the sediment, I was referring to the variable density of cells within the column of the sediment. Certainly the cell density is higher at the bottom of the column than at the top, and I’ve not seen data to confirm that the average cell count per milliliter is the same for various volumes of semi-packed cells. WIthout validation of the method, one cannot reliably compare the measured values from one experiment to another in a strictly mathematical way.

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