HOMEBREW Digest #5145 Tue 13 February 2007

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  RE: Correct amount of hops for full-boil ("Tim R")
  Re:Temperature vs. alcohol tolerance ("-s.alexander")
  English Mild recipe help... (Michael Eyre)
   ("Elston Gunn")

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---------------------------------------------------------------------- Date: Tue, 13 Feb 2007 07:11:19 -0500 From: "Tim R" <tim.runnette at gmail.com> Subject: RE: Correct amount of hops for full-boil I believe Ray Daniels also addresses this topic in Designing Great Beers. I like ProMash (http://www.promash.com/) for simplicity. I've heard Beer Tools (http://www.beertools.com/) is also good according to this month's BYO. The only place I have not tweaked the numbers is in the case of late addition DME boils where hops are added early to a full-wort, partial-mash, low OG wort and then I add the DME during the last 15-30 minutes of the boil. I am sure this results in greater utilization. Return to table of contents
Date: Tue, 13 Feb 2007 08:09:09 -0500 (EST) From: "-s.alexander" <-s at adelphia.net> Subject: Re:Temperature vs. alcohol tolerance Bill Pierce asks about yeast performance vs temperature, Unfortuantely today I'm in hotel room and separated from my reference material; however there are some clear points (minus a few details), > I am posting this because of a currently ongoing discussion from the > Mead Lover's Digest, where someone has posted the recommendation to > conduct high gravity fermentations at a lower temperature of about > 60 F in order to increase the alcohol tolerance of the yeast. As > evidence they cite the claim that distiller's yeast, which is > normally fermented quite warm (as high as 100 F because there is > little concern about the production of fusels), exhibits higher > alcohol tolerance when fermented at 30 C (86 F). Alcohol tolerance is a bit of a misnomer. Common brewing yeast can ferment effectively into the mid-teens (say 15%ABV) with a little care and can ferment to the low 20s (20-22%) in studies where osmoprotectants are added. So common yeast are typically not up against their limitations even in wine. The osmotic pressure on yeast cells increase dramatically as they 1 mol of glucose to 2 mol of ethanol; a mol of maltose to 4mol of ethanol, and a mol of maltotriose to 6mol of ethanol. The increase in solute molar concentration in the fermentedd stuff makes it more difficult (as in requires more energy) for yeast to transport various ions from inside the cell to out. This is directly relatable to the concept of "water activity", Ac, in biology. Somehow in that semi-magical set of genetic mechanisms, yeast sense when they are no longer making enough overall energy to continue economically continue and they instead flocculate (in the case of commercial yeasts) and go dormant, stop fermenting. WRT temperature and whisk[e]y - the issue is probably related to increasing the rate of fermetation and thus improving the factory throughput. In Scotch Whisky the wort is in the normal gravity range(12-15P), common ale yeast - often from local beer breweries was traditionally used, so alcohol level is not very high. Also I can't recall Scotch distillers using such high fermentation temps as mentioned. I can't recall the gravity in US distilling but I seem to recall that it was somewhat higher. In both the fermentation is never quite allowed to finish as their are considerable (5%-ish) ethanol losses in open fermenters. Anyway the primary difference between a successful hi-grav ferment and a stuck one is the quality of the yeast cell membranes, not the temperaure. Yeast cell membranes require oxygen products - UFAs and stereols. UFAs are required for membrane permiability at LOW temps, and pitvching yeast (their O2 uptake phase) at lower temps causes more UFA production. This is the reason why it's a bad dea to pitch yeast into warm wort then then later cool the fermenter (esp for very low temps) when you want a clean ferment. Yeast do ferment faster at higher temps - up to some peak, but also product more objectional secondary products, so in beer and wine we always ferment well below the "fastest" ferment temp. Also removal of CO2 and the addition of certain osmoprotectants (certain amino acids) can greatly aid in a hi-alc brew. Yeast themselvees can produce trehalose as a stress reducing substance and tests have been carried out were yeast were heat treated (mmoentarily brought to a very high temp) and when they recover their trehalose levels are enhanced and they perform extremely well for a while. > The suggestion is > that mead and wine yeast exhibit similar properties and therefore > should be fermented cool in a high alcohol environment. Extending > the logic would lead to a similar conclusion for brewing yeast. I > must say I have never encountered this recommendation before in my > reading and study. Would someone else care to comment? Well the membrane intergrity is worse at high temps, but I don't believe that means it is better at very low temps. My hunch is that anything much below ~80F will produce similar results for S.cervis strains. Wine yeast have a greater ability to accumulate sterol than their ale strains cousins (among S.cerevis). Of course champagne yeast is a different critter - more closely related to lager yeast - and should be treated differently. Still the methods used to ferment hi-grav are the same. Be sure you have enough oxygen product (sterol & UFAs) in your fermenter or you cannot succeed. This may mean a well aerated starter or re-aerating yeast somehow or re-pitching. Drive off excess CO2 as it stalls the yeast energy pathway. Also incremental feeding (slowly increasing the effective SG) is used to acheive the very highest ethanol levels. I am not a mead maker, but I think that adding honey incrementally should mean that incremental feeding is much easier for mead than for all-grain brewing. later, -S Return to table of contents
Date: Tue, 13 Feb 2007 12:24:20 -0800 From: Michael Eyre <meyre at sbcglobal.net> Subject: English Mild recipe help... Hey all. Looking for a bit of help in an English Dark Mild recipe I whipped out the other week. It's on tap now and I'm getting a bit of a 'tang' out of it that I'd rather not have, sorta like the Guinness taste. I'd rather it was more mellow than it is. Here's the layout: 11 gallons, all-grain: 12lbs English Pale Ale malt 2.25lbs Dark Crystal 150L 0.4lbs Chocolate 2oz EKG 5%AA at 60min 1oz EKG 5%AA at 10min Safale S-04 One hour at 153 degrees single infusion. Batch sparged. 90minute boil. 3.2%abv all told and a nice dark, mahogany-ish brown color, just like I was shooting for. Bitterness seems right on par, with very little, just enough to balance. Low carbonation, at about 1.6-1.7 volumes, according to my regulator and charts. Thing is, it's that tang I get in the flavor that I'm not digging totally. Is that par for the style? Either case, it seems just a tad over the top, and I'd like to take the edge off of that. I'm basing this recipe of a lot I've seen posted, but mostly from data gathered from Ray Daniels book... I' guessing it's the Dark crystals that are doing this, but I'm not sure. Any ideas? Mike Return to table of contents
Date: Tue, 13 Feb 2007 17:09:55 -0600 From: "Elston Gunn" <elston_gunn at comcast.net> Subject: Is there a decent extract lager 'kit' available from one of the usual on-line retailers? Or a recipe? Or, is lager really not do-able in the extract world? I never brewed a lager, but have done several ales. Thought I would take advantage of these cold Minnesota days. Return to table of contents
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