HOMEBREW Digest #3254 Mon 21 February 2000

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  AOL home brewing message boards (BsmntBrewr)
  enjoying yeast discussion plus question (John_E_Schnupp)
  Re: FAN/amino acids in yeast nutrient (patrick finerty)
  Re: liquid yeast in toronto (patrick finerty)
  Off Flavors/Wyeast/FAN/Pitching/Skunkiness/Water ("A. J. deLange")
  Liquid Yeast in Toronto ("Rob Jones")
  Decotion heat source...does it matter? (William Macher)
  FAN and fusel alcohols (Dave Burley)
  Pitching Rates (KMacneal)
  Airstone Carbonation (Dan Listermann)
  high temperature wort settling ("Stephen Alexander")
  contaminated yeast/Fusels/Yeast  (starter) Questions ("Stephen Alexander")
  more pitching rate ("Alan Meeker")
  contamination (Aaron Perry)

* Beer is our obsession and we're late for therapy! * AOL members: Visit the AOL Homebrewing boards before they're gone! * Go to aol://5863:126/mBLA:185893 * Entry deadline for the Mayfare Homebrew Competition is 3/15/00 * See http://www.maltosefalcons.com/ for more information Send articles for __publication_only__ to post@hbd.org If your e-mail account is being deleted, please unsubscribe first!! To SUBSCRIBE or UNSUBSCRIBE send an e-mail message with the word "subscribe" or "unsubscribe" to request@hbd.org FROM THE E-MAIL ACCOUNT YOU WISH TO HAVE SUBSCRIBED OR UNSUBSCRIBED!!!** IF YOU HAVE SPAM-PROOFED your e-mail address, you cannot subscribe to the digest as we canoot reach you. We will not correct your address for the automation - that's your job. The HBD is a copyrighted document. The compilation is copyright HBD.ORG. Individual postings are copyright by their authors. ASK before reproducing and you'll rarely have trouble. Digest content cannot be reproduced by any means for sale or profit. More information is available by sending the word "info" to req at hbd.org. JANITORS on duty: Pat Babcock and Karl Lutzen (janitor@hbd.org)
---------------------------------------------------------------------- Date: Sat, 19 Feb 2000 00:04:55 EST From: BsmntBrewr at aol.com Subject: AOL home brewing message boards Greetings brewers, I would like to invite any AOL based HBD subscibers, Pat says there's a bunch of you, to check out the AOL homebrew message boards. Yes they are out there but impossible to find. In fact I can't find the boards without my "Favorite Places" link. Pat Babcock is a moderator on the boards and regularly participates. Marty Nachel, author of Home Brewing for Dummies, is also a another notable regular contributor as well. The boards are no substitute for our beloved HBD but are a great resource as an addition to it. One of the best features is that there are atleast 37 different catagories of brewing topics that you can post to or just browse at your leasure. To get there open your Favorite places and click on the "new" button. You will be prompted to enter a name for the new link and the "internet address" Just copy and paste the following line of text into the internet address field and save it. aol://5863:126/mB:185893 To get there just click on your favorite places option then click on the link you just created. If you have trouble doing this email me and I'll send you a hyper link in your mail. No flame suits required, we're a pretty easy going bunch. Pop in and say hi. Brew On! Bob Bratcher Roanoke, VA Star City Brewers Guild <A HREF="http://hbd.org/starcity">http://hbd.org/starcity</A> Return to table of contents
Date: Sat, 19 Feb 2000 00:46:00 -0800 From: John_E_Schnupp at amat.com Subject: enjoying yeast discussion plus question Digest 3250 is full of yeast info. >From: "George de Piro" <gdepiro at mindspring.com> >I find it safest to not provide continuous aeration, but rather >to aerate for several hours, let it ferment out, and feed and aerate again >the next day. This has worked for me. Results may vary, and I'm sure their >are others who will chime in with alternate techniques that provide good >results. I use stir and aerate continuously. I use a HEPA filtered aquarium pump to get fresh air into the top of my starter vessel (4L wine jug). I do not bubble the air thru the starter. Use a two hole stopper and pump air in one hole and attach an air lock to the other. The stirring action will provide enough (I told) aeration. I typically start with a smack pack into about 1 pint. Approximately every 24 hours I add another quart. I usually add 2 quarts. I stop the aeration several hours after the final quart and keep the stirrer going. When the bubbling has slowed, I stop the stirrer so that the yeast can settle. I like to allow at least 24 hours for this but have gone less. On brew day I drain the spent liquid and add a fresh quart after I have the mash going. By the time I'm ready to pitch the yeast is at full trot. I used to think that folks who said they had lag times of 2-4 hours were nuts, now I know better. >From: Spencer W Thomas <spencer at engin.umich.edu> >You want 8mg/l of O2 dissolved into the wort. The 1.7 g of O2 in the >carboy divides out to 90g/l, assuming 19 liters of beer in the carboy. >So, yes, there is plenty of O2 in the headspace. How about that! I made an aeration tube for the drain from my brew pot. I used the tip from a butane lighter. I used one of those grill lighters. The fuel tip was brass and the opening is very small. I drilled the correct sized hole in the as long as it takes to fill empty the brewpot. My drain is 3/8" copper so it takes a little longer. I've never noticed anything that would indicate that I'm not getting enough aeration. >From: "Parker, Mike" <mparker at CaseServices.com> >You don't need a microscope for counts. You pull a 1 ml sample >sample from that, dilute x 10 again, and repeat for something like >6 times total. Then pour the last 10ml sample onto an agar petri >dish, let it grow a day or so, then do an eyeball count. If you >diluted right you should get around 10-100 colonies. Back-calculate >by multiplying your count by 1x10E<#dilutions> to get your count/ml, >then multiply by your starter size to get the total count. Never though of this. This sound like a very "quick and dirty" way to get a good idea of cell counts. I don't have a scope and wasn't really planning on it, but I've always wondered about what kind of cell count I was getting. I've never grown anything on an agar petri dish. I'm assuming that it would/should be obvious to tell the differenct between a yeast colony and a bacteria colony. IOW, wouldn't this also be a rough test for possible infections? Question: based on my above starter method, when should I pull the first 10 ml sample? When I'm ready to pitch or from the slurry before I add my final refresher wort on brew day? I would think the best time would be right before I pitch but at that point there's so much foam that it'd be hard to get all the yeast suspended into final quart of starter liquid. I would also think that 10 ml of very thick slurry should have more yeast than a slurry that hasn't had time to settle as much. Kind of a subjective thing I suppose, but adequate for a ballpark idea. John Schnupp, N3CNL Dirty Laundry Brewery (temporarily closed) Georgia, VT 95 XLH 1200 Return to table of contents
Date: Sat, 19 Feb 2000 09:42:40 -0500 (EST) From: patrick finerty <zinc at zifi.psf.sickkids.on.ca> Subject: Re: FAN/amino acids in yeast nutrient hi, i'm not really a yeast expert but i'm feeling brave so i'm going to give it a try. On February 18, 2000, Fred L. Johnson wrote: > To the yeast culture experts out there: > > Could someone provide a brief summary of > 1) the requirement for free amino nitrogen by yeast for growth, (i.e. > is free amino nitrogen "required" for growth or just to prevent fusel > alcohol production?) like all living organisms, yeast need to make nitrogen-containing macromolecules (proteins, nucleic acids) to survive. as such, they require a source of nitrogen. nitrogen can be supplided as free amino acids or as NH4Cl (ammonium chloride). free nitrogen should not be necessary if there are enough of all amino acids present in the wort. i know deamination reactions are nearly absent in bacteria when they are grown in a media containing sufficient amounts of all 20 amino acids (i prepared some 15N-Leu labeled protein this way last summer). obviously yeast aren't bacteria but i'm going to take a risk and assume they would behave similarily. the deamination reactions are used to make one amino acid type using a different type as the starting point. > 2) the amino acid requirements by yeast for growth yeast do not require amino acids for growth. rather, they can make them using only NH4Cl and a carbon source (glucose). in the lab yeast can be grown using a very simple minimal media containing NH4Cl, glucose, a phosphate source (usu Na(2)H(2)PO4) and a couple of vitamins (enzyme cofactors). > 3) the concentrations of the above that can be expected in all grain > worts, and can't really answer this but i can say it will vary depending on the type of grain you use. perhaps the company that does the malting has done an analysis of the amino acid content of their grain. > 4) the situations in which supplements to the wort might be required? the only time i ever hear about people adding supplements regularily is when making meads. in that case you have a very high gravity liquid that will require the yeast to ferment for a long time (ie, keep living for a long time). since honey doesn't really have much in the way of amino acid or nitrogen content the yeast need it provided to them. > In regard to the above questions, I have seen diammonium phosphate as > a common ingredient in "yeast nutrients". Is this to prevent fusel > alcohol production, or is this to enhance yeast growth, or are these > issues not related? i assume it is to provide yeast with nitrogen when the growth media (say wort prepared with DME) is defficient. when a particular amino acid type is defficient, deamination reactions will be employed to make that amino acid. i don't think providing yeast with something like NH4Cl will stop these reactions. however, i may be mistaken. > Protein hydrolysates and peptones are also typcially found in "yeast > nutrients". Apparently amino acid concentrations can be deficient at > times. I assume these are necessary under conditions in which amino > acid concentrations are low (musts?). I also have seen added thiamine > in mixtures of "yeast nutrients" or "energizers" for homebrewers. I > assume this is an essential amino acid that con be deficient in worts > (or perhaps only in musts). many hydrolysates such as peptones are made from yeast. it is sort of strange to grow yeast on hydrolysates of yeast but they're really quite happy growing in it. when i grow yeast for brewing in the lab i always start with YPD: 10 g yeast extract 20 g Peptone 1 liter dH2O adjust pH to 5.8 with HCl autoclave 30-45 minutes and cool to 65 degrees C, then add 50 ml of sterile 40% glucose actually, for this last batch of beer i grew the yeast in YPD the whole time and simply collected the cells by centrifugation, resuspended in some wort and then pitched. i'd be curious to hear when people thought about using YPD the whole time like this as far as flavor of the beer is concerned. thiamine is vitamin B1. it is an enzyme cofactor. here's a nice link all about thiamie: http://chemistry.gsu.edu/glactone/vitamins/b1. > I would like to better understand the driving force behind fusel > alcohol production (which, of course, can be a flavor problem with > beer) versus the limitations on yeast growth. I wish > to better understand the issues behind making yeast versus making > beer, so that I can control these at the APPROPRIATE TIME during the > process. Culturing yeast for brewing is not the same as brewing beer, > and the two processes should not be confused. i think a simple guide is to grow the yeast initially in the best media you can produce. this probably means using something like YPD. prior to pitching, you will probably want to use wort, possibly supplemented with yeast nutrients if the wort is thought to be deficient. i thank those who are more knowledgable about yeast metabolism for being kind when they point out the errors in this post! -patrick in toronto - -- "There is only one aim in life and that is to live it." Karl Shapiro,(1959) from an essay on Henry Miller's Tropic of Cancer finger pfinerty at nyx10.nyx.net for PGP key http://abragam.med.utoronto.ca/~zinc Return to table of contents
Date: Sat, 19 Feb 2000 09:49:04 -0500 (EST) From: patrick finerty <zinc at zifi.psf.sickkids.on.ca> Subject: Re: liquid yeast in toronto howdy rod, you can get liq yeast from Brew-Your-Own, LTD. they're just down the street from the U of T at McCaul and Baldwin. Barry, the owner, is a pretty knowledgable and helpful guy. i was just there yesterday to pick up my shiny new Valley Mill... call them at 977-2289. -patrick in Toronto (std disclaimer...) On February 18, 2000, Rod Kwok wrote: > > hi, > i was hoping that someone on this news group could point me towards a > source for liquid yeast in toronto or at least in ontario. i've > contacted white labs (a while ago) and their closest source i think was in > ohio. i don't think i got and answer from wyeast. my problem with mail > order from the states is that the shipping rates are usually double (or > more) when the package passes the border. Return to table of contents
Date: Sat, 19 Feb 2000 15:11:02 +0000 From: "A. J. deLange" <ajdel at mindspring.com> Subject: Off Flavors/Wyeast/FAN/Pitching/Skunkiness/Water Wil Kolb asked about doping beers for training. This is invaluable. Some of the chemicals (acetaldehyde, diacetyl, ethyl acetate, ethyl hexanoate, geraniol, etc.) are readily enough available to anyone who works in a laboratory but will be difficult to obtain otherwise and they are somewhat expensive. There is a company in the UK called FlavorAktiv (I think that's how it's spelled) that sells nifty little kits for exactly the purpose Wil has in mind. The off flavors are bound up in powders in little capsules. Just add to water or megabrew and you're off and running. You know there has to be bad news here. The cost is astronomical - so bad that their literature suggests that several small breweries in an area may wish to pool their funds to buy one kit. Several home-brew clubs might do the same. For DMS offer Rolling Rock. For mercaptans see "to Dr. P" below * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Several of the times I've put the contents of a Wyeast package under the microscope I've found a thing or two that isn't a yeast cell. I've never had a bad result from proper use of a Wyeast product. Put those two facts together and I hope what is the essential truth will emerge. Wyeast cultures are not pure but grown up properly the occasional stowaway bugs haven't a chance. Note: I also find grains which are not barley in the malts I buy. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Let me have a whack at a couple of Fred Johnson's questions - I'm sure others can fill in where I'm thin. >1) the requirement for free amino nitrogen by yeast for growth, (i.e. >is free amino nitrogen "required" for growth or just to prevent fusel >alcohol production?) I'd say "both". Yeasts, like other living things, require amino acids for the formation of protein (including the enzymes we rely upon to turn sugar to alcohol) and thus need them to grow and reproduce. Some amino acids can be synthesized, some must be supplied. Because they are needed for growth yeast will synthesize them if they are not supplied. The problem is that synthesis sometimes uses pathways which branch to fusel production. Often the amino acid produced by this same pathway has an inhibitory effect on an early step. For example, valine blocks alpha acetolactate synthase slowing conversion of pyruvate to acetolactate and thus reducing the amount of isobutanol (and, as an added benefit, diacetyl) formed by the valine synthesis pathway. Thus, a hefty valine level is desirable in wort for two reasons. >2) the amino acid requirements by yeast for growth I'll leave this one to the experts but I seem to remember seeing 200 mg/L as a lower limit for wort. >3) the concentrations of the above that can be expected in all grain worts, and The following are some FAN numbers from my brewing logs. All are in mg/L Ale 217 Pils 352 Fest 369 Weizen 197 Pils 354 Pils 369 It's quite clear that the lagers have a higher level than the ales. All the lagers are decocted (but so is the Weizen) >4) the situations in which supplements to the wort might be required? I think a rule of thumb might be when it falls under 200 but that's a rule of thumb subject to all the caveats that go with rules of thumb. If you brew a tasty beer with a FAN of 100 pitched at a million cells/mL, enjoy it! Extracts are notorious for being low in FAN but the one or two I've measured did not confirm this. I seem to recall an article in one of the magazines where a whole bunch of extracts were tested. * * * * * * * * * * * * ** * * ** * * * * * * * * * * * Just got to put in my oar on the raging pitching level debate. There seems to be a feeling among some that if it's in a textbook or done by a megabrewery, it's wrong - that it's got to be artisanal to be good. Horse feathers! Megabrews are, like American movies and television, technically superb - just insipid. While the basic premise that eccentric practices can, and do, produce excellent beers is certainly valid there are few, if any of us, on this forum well enough grounded in the fundamentals that we can dismiss them out of hand. You'd better sweat through the Czerny before attempting the Goldberg Variations. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To Dr. P: Try the skunking experiment with half an hour of direct sunlight. With a beer that hasn't been brewed with preisomerized (I use American Budweiser for this demo) hops your panel shouldn't even have to taste the beer. I've had classes gasp as soon as the crown is removed. And my test tube is just as large as it needs to be! * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * For Jeff Lutes: Weird water report - not that the water is so weird but the data. As a brewer you don't care about ppb levels of heavy metals (you do as a consumer though). You need to know alkalinity (or bicarbonate level), sodium, potassium, hardness (magnesium, calcium). These are usually present in much larger quantities than things like zinc and are usually reported. Given this limited data I can only roughly estimate the alkalinity of the water at about 30 ppm as calcium carbonate and the bicarbonate level at about 36. Any magnesium, potassium or sodium present, and there must be some, would raise this estimate somewhat but I don't think by much because if the alkalinity had to go higher the pH probably would probably be higher than it is. In any event, the water looks pretty good for brewing. Given the estimated alkalinity level you should have no trouble establishing mash pH for the majority of brews and no trouble controlling it with high kilned malt or chalk where necessary. The low level of sulfate means that brews with high levels of fine hops can be done. For Burton style ales, Exports, etc., sulfate can be supplemented with gypsum, Return to table of contents
Date: Sat, 19 Feb 2000 09:51:21 -0500 From: "Rob Jones" <robjones at pathcom.com> Subject: Liquid Yeast in Toronto Rod, Contact Brew Your Own, downtown on McCaul St. Barry carries a good selection of Wyeast, White Labs and Yeast Lab, all fresh. He's also a good source (basically the only source in Toronto) of info and supplies on all grain brewing. Phone 416-977-2289 Good brewing, Rob Jones Secretary, Canadian Amateur Brewers Association http://realbeer.com/caba/ Date: Fri, 18 Feb 2000 09:41:59 -0500 (EST) From: Rod Kwok <rdkwok at zoo.utoronto.ca> Subject: liquid yeast in toronto Return to table of contents
Date: Sat, 19 Feb 2000 10:09:50 -0500 From: William Macher <macher at telerama.lm.com> Subject: Decotion heat source...does it matter? Hi All, Ok! I have a confession! My name is llib rehcam. This Macher thing is just a pseudonym I use to prevent fires when posting to the HBD, which I rarely do anyway...Oh my, a dilemma! Why am I using this Macher handle in real life? Or am I? Better cover this with my wife in the morning...but she is a refugee from napaJ...not sure if she counts...guess I better consult with selected posters from this forum later....It's just that as a young boy years ago I could not explain why a first name could be a last name. Yea, that must be it...which came first anyway? I love my HBD. I love my HBD...my morning chant on the way to my...my...my favorite reading spot! Gee, am I the only one that knows that Dr. Pivo is real and in another existence goes by the name of Jeff? My, my...what happened to Arnold Chickenshorts? He certainly had more substance to post here than many of us. Did we have to drive him away because he did not stand behind an identifier that made us feel comfortable? I keep thinking his name might be George...No, I mean the other George, the 2 + 2 one...Will I be flamed because my name seems real? Doubtful. Are you certain it is? George De' probably does have the ability to split beers in to the many taste components that are there. Should we drive him down because this is so, or because he thinks it is so? Chances are it is so. So? Would be nice if Al K. dropped by again sometimes. But three little ones can take so much of one's time...Dave B does go on and on...I am glad he is here even if he did stress the big "C" pretty heavy for a while. You know what "C" I mean... Steve A and A. J. your posts are always appreciated. I am sure even a bunch of us appreciate the spinning cat stories...Jack S. spins a tail or two too...or is that tale...oh...whatever...All the other regulars thanks to you too...alan and alan are you the same or different? This Belgian style ale I have been sippin' for a bit is pretty goo...on to my question, here, here! Decoctions by fire versus steam. I know most decoctions are done over a flame of some sort. Would it be likely that a decoction that was heated by injection of steam into the vessel holding the decoction would produce the same results? It would be easy for me to set up a steam heated decoction vessel, but much less convenient to install a burner to use as the heat source. My uncertainty is whether the flame actually caramelizes [oh, oh! Another spelling error? Tsk, tsk...] the grains due to overheating at the interface with the bottom of the pot. Would it be likely I could get the same result if I used steam to boil the grains rather than a flame under the pot holding them? With my setup the steam would not exceed about 220 degrees F. Gee I said grains...better cover that with "thickest part of the mash..." Fire VS steam for the decoction heat source. Any practical difference? Appreciate any opinions or experience. By the way, you know what really amazes me? Well, in previous travels I REALLY LIKED some of the beer in England, and in Belgium and Holland and Germany and the Chec Republic and France and...and... And I really DID NOT LIKE some of the beer in England, and in Belgium and Holland and Germany and the Chec Republic and France and..and... Bottom line is I know there is a wide spectrum of tastes out there in the real WORLD. I know that my homebrew falls within this spectrum somewhere. Tastes good to me, and to others (who may like it simply because the price is right). What do they know anyway? The spectrum is broad. My guess is many do not know how broad it really is...Under pitching of yeast [by our American standard] may not be as evil as some portray it to be. It is still a big world out there. Napal and napaJ are not the same place by the way. Refugees from napaJ are few and far between, that is what makes mine so special! Beer by any other name is just another pivo! Swingin' tails in Pittsburgh, Pa USA...or is that singin' tales? Better check our karaoke machine...this mike looks so much like a mouse...why aren't those speakers workin' as I sing into this thing???? What's goin' on here...How'd this glass get empty so quick. Which one of you kids has been sneakin' up here???!!! what's HBD mean...where am I? Have bun...ah... FUN! If i knew where I was I'd tell ya' Jeff! I need help! No, not the pivo Jeff! I mean the the Jeff we all revolve around! Jeff! Where am I....................? llib rehcam PS - Eric...or was that Erik? I want one of these pocket cobras...how'd you do that? Return to table of contents
Date: Sat, 19 Feb 2000 10:24:48 -0500 From: Dave Burley <Dave_Burley at compuserve.com> Subject: FAN and fusel alcohols Brewsters: Fred asks about FAN ( free amino nitrogen) and fusel alcohols and related subjects. FAN are non-protein, non-ammonia nitrogen which can be assimilated by yeast. This includes amino acids, amines and whatever low molecular weight organic compounds with nitrogen attached to a carbon including low molecular weight, LMW, peptides. FAN does not include 'ammonia' as far as I know. FAN is closely related in content, but not TSN ( total soluble nitrogen), which also includes ammonia/um compounds. FAN and TSN are important for yeast growth and low attenuation, since it relates to the health of the yeast colony. If you reduce the amount of FAN or TSN too much, such as putting too much sugar into an extract batch, you will reduce the nitrogen content too much and likely you will end up with an underattenuated batch. Yeast nutrients often add ammonium phosphate as a way of boosting TSN. As Fred notes, some nutrients add hydrolysed protein as a way of boosting FAN without adding salts and risking the precipitation of calcium with the addition of phosphate. Peptones are sometimes added and would provide LMW peptides for yeast utilization at the expense of higher MW proteins, not always a good thing. Although I have read elsewhere that yeast preferentially utilizes ammonia/um compounds until these are depleted and then goes after other sources of nitrogen, namely the FAN, M&BS says the ammonium ion ( often called "ammonia") may or may not be utilized, depending on the yeast strain and that it utilizes amino acid nitrogen preferentially. ( M&BS 2nd ed. p 596). When yeast uses an amino compound it removes the nitrogen ( deamination) and in the place of the N-H substituent is substituted an O-H or C=O. If this is a primary amine ( on the end of the carbon chain) it can form a a fusel alcohol. This is is an alcohol with a carbon chain longer than 2, so it is called a fusel alcohol, since it is part of the residue left after beer distillation. The lower molecular weight fusel alcohols are solventy smelling and have high vapor pressures, so can have a real impact on beer aroma even at low concentrations. Fusel alcohol formation is a function of yeast growth and amino nitrogen metabolism. Also: M&BS 2nd ed. p 599 "Since the yeast oxo-acid pool is derived from both carbohydrate metabolism and wort amiino acids, both may serve for generating these precursors of fusel alcohols." M&BS says ( 2nd ed p 601) "Apart from the particular properties of yeast strains, the principal factors leading to elevated fusel alcohols in brewery fermentations are 1) elevated levels of amino acids in worts 2) anaerobic conditions 3) high temperature 4) continuous agitation 5) large amount of yeast growth 6) high alcohol concentration" Apart from the continuous agitation comment, these are biochemical phenomena. Anyone care to explain how agitation causes the formation of fusel alcohols? Keep on Brewin' Dave Burley Return to table of contents
Date: Sat, 19 Feb 2000 11:41:14 EST From: KMacneal at aol.com Subject: Pitching Rates In a message dated 2/18/2000 12:26:11 AM Eastern Standard Time, "George de Piro" <gdepiro at mindspring.com> writes: << The flavors that most beers will acquire from yeast abuse (i.e., underpitching) are NOT pleasant to most people. If you like the solvent flavor of ethtyl acetate or the heady, harsh character of fusel alcohols, by all means underpitch your wort. Most people do not like these flavors, though. A "full-flavored" beer will express its fullness in malt, hops and balanced yeast by-products that result from a healthy fermentation. Messing with your yeast (underpitching and/or underoxygenating) will yield unpredictable and often unpalatable results. You most certainly cannot expect to harvest and repitch yeast from such a fermentation. This is really a pointless argument. Countless commercial brewers and brewing scientists have demonstrated the results of "proper" fermentation management. If a couple of homebrewers, whose beer most (none?) of us have ever tasted, wish to question these well-tried practices, that is fine. Be aware that these guys are in the minority, though, and unless you taste their beers and find them acceptable, question their assertions. >> Like I said in an early post, I follow the recommendations of the homebrewing texts and the Classic Beer series and pitch a 1 pint starter for ales, a 1 quart starter for lagers, and a 1 gallon starter for high gravity beers (scotch ales, doublebocks, etc.). I aerate the wort by pouring it through a strainer into the fermenter after chilling and then doing some stirring. The score sheets I've received from BJCP certified judges have never mentioned the defects George lists above. I can understand the need for commercial brewers to pitch large quantities of yeast -- they want to turn beer around as fast as possible and minimize potential sources of batch to batch variablilty. As a homebrewer with other things competing for my time, I find an acceptable trade-off between these alleged underpitching rates and the time and effort needed to grow large starters using accepted commercial practices. I have noticed underattenuation when pitching directly from the swollen yeast package vs. pitching with more yeast. I brewed the same recipe on consecutive weekends. I didn't plan ahead and pitched directly from the pouch on the first batch. The second batch was fermented on the yeast cake from the first batch. The second batch finished at least 10 points lower than the first batch Someone asked about pitching these starters into the wort. I pitch my 1 pint and 1 quart starters into the wort in their entirety (and yes, I add 1pint of wort to my 1 pint starter to get a 1 quart starter). If I'm pitching a gallon of starter, I will let the yeast settle out, decant the liquid off, add a pint of wort to the yeast cake and make sure it's active before pitching that. If I'm thinking ahead, I typically brew high gravity beers the same day I rack a batch into secondary so I can have the benefit of the yeast cake from the prior batch without going through the hassle of growing up another starter. Keith MacNeal Worcester, MA Return to table of contents
Date: Sat, 19 Feb 2000 11:59:50 -0500 From: Dan Listermann <72723.1707 at compuserve.com> Subject: Airstone Carbonation Aaron Perry (vspbcb at earthlink.net) writes about counterpressure filling a keg that had been carbonated with an air stone: <Last week or so I made a post in regards to using a counterphil on a keg carbonated with a carbonation stone. BAD MOVE!!! I'm not sure on the specifics of what went on, but the beer was some how pushed backwards??? sort of a reverse loop??? The CO2 usually is pumped into the headspace of the keg, with the stone, it bubbles up through the beer. I can't figure what's happening, all I can say is that it didn't work. I set it up and attempted bottling, failed, then bottled a braggot ( Regularly force carbonated-no stone) without incident. The braggot went so smoothly that I gave the stone carbonated brew a whirl again......Same thing!!!> I dont know, but it seems to me that he may have been trying to pass beer up through the dip tube with the stone still attached. This will not work as the stone offers a lot of resistance to flow for a liquid. This problem would even slow a picnic faucet to almost uselessness. To get the beer out the stone will have to be removed. If he wants to leave carbonation stones in the keg after it is carbonated, he should consider attaching the stone to the "in" tube and invert the keg for the carbonation process. This way the air stone will only pass gas, no beer and the "out" tube would not be clogged. Dan Listermann dan at listermann.com 72723.1707 at compuserve.com Return to table of contents
Date: Sat, 19 Feb 2000 11:11:40 -0600 From: "MrWES" <killshot at enteract.com> Subject: WATCH Brian Wrote... No. The directions on the labels are for commercial use. For homebrewers we recommend 2 oz. of PBW per 5 gallons of solution. Let me explain the discrepency. With cleaning and sanitizing chemicals, there are three main factors, concentration, temperature and length of time of exposure. Basically, if one of these three factors is decreased for whatever reason, another must be increased to obtain the desired effect. Commercial brewers are usually using PBW for CIPing a kettle or fermenter and the actual exposure time is often reduced. Therefore, they make it up with a higher concentration. I wrote... Brian is actually referring to a formula in the sanitation industry called WATCH: W =3D Water A =3D Aggitation T =3D Temperature C =3D Chemical Consentration H =3D Heat Each represent 20% of a successful cleaning and/or sanitizing regemine. If one portion the formula is missing or reduced, you need to increase the other to make up for it. Sometimes it's by design. Another words, if commerical brewers engineer their CIP (Clean In Place) systems for a quicker (shorter) contact time -- as to reduce downtime of the equipment, they may increase consentration, aggitation, or introduce heat to make the chemical more effective. Bill P.S. Nice to see you posting Brian :) Return to table of contents
Date: Sat, 19 Feb 2000 13:57:37 -0500 From: "Stephen Alexander" <steve-alexander at worldnet.att.net> Subject: high temperature wort settling Joe Gibbens asks .. >If the "hot break" gradually comes out of solution as the temperature >drops, where is the line drawn between hot and cold break? Generally hot break forms in the boil. You will continue to get additional cold break all the way down to the freezing point. It isn't a temp vs solubility issue since the particulate break is not in solution. The flocs are just forming big enough particles to sediment rather than stay in suspension. -S Return to table of contents
Date: Sat, 19 Feb 2000 13:17:28 -0500 From: "Stephen Alexander" <steve-alexander at worldnet.att.net> Subject: contaminated yeast/Fusels/Yeast (starter) Questions Nathan Lansing writes ... >Scott Laboratories will send you a "typical" analysis [...] >Cooper's also publishes this information. I'd like to commend ANY brewing yeast producer willing to release such analyses. >So what's the worry? Do you think large commercial breweies >are working with 100% pure pitching yeast? AB's microbiologic controls are legend. They are certainly not tolerating the levels of contamination you quoted for Danstar. >They acid wash each pitching. Wrong. Acid washing is performed after several brewing cycles by micros and small breweries and will cause abnormal growth patterns afterwards. Acid wash yeast must be regrown to a normal state, or at least the resulting beer must be mixed with normal beer for QA reasons. Acid washing does not eliminate wild yeast (perhaps the most pernicious infection problem - difficult to ID or treat). The big boys I suspect keep separate pitching cultures from plated out and recultured yeast. >Even if you had a laboratory and picked a single cell and grew it in >autoclaved flasks under sterile conditions, wouldn't you be pitching it >into a rather unsterile fermenter? Right. A well sanitized fermentor is only stop-gap, which is why most of us can't repitch forever. === D.Burley writes ... >George De Piro says that when you >get high growth rate you always get >high fusel alcohols and believes it >is an absolute. Not so. As I >understand it, If the supply >of simple nitrogen from things other >than amino acids is sufficient, then no >amino acids will be deaminated >and no fusel oils formed. I can't agree at all. The model originally developed by Ayrapaa 4 decades ago and repeatedly verified since is that there are two mechanisms for fusel creation. The one Dave is apparently aware of is the Ehrlich mechanism which goes back many decades further to 1906 (yes - it's the "magic bullet" Ehrlich). The other is a synthetic mechanism which is dependent in the synthesized oxo-acid pool. The Ehrlich mechanism is related to a large consumed oxo-acid pool and certain carbo fermentation products control the rate. Both are fairly directly related to yeast growth rate. If amino acid concentrations are high, then the synthetic mechanism is almost halted. If low, and nitrogen is available, and growth is occurring , then the synthetic mechanism is dominant. Dave is wrong about this too. The amino acid level is the controlling factor, not the nitrogen level. If both the aminos and nitrogen are present, yeast selectively use the amino acids. There are other fusel mechanism, such as the reduction of proprianate to n-propanol, and ones related to catabolism of odd-chain fatty acids. These may be factors under special circumstances. Forcing yeast to use inorganic nitrogen to synthesize oxo-acids also reportedly has bad flavor consequences in beer. Bottom line. I don't have figures which separate out the relative contributions of the two major synthetic mechanisms of fusels, and this is probably very strain dependent. The graphs I have seem show a very strong correlation between cell growth RATE and fusel production RATE - just as George de Piro said. My experience is that worts low in amino acids (like bad kits) can produce horribly fusel-y beers. Also yeast in barleywines often also produce obnoxious levels of fusels because of the high amino acid levels and high ethanol content. Two different mechanism to the same bad result. My advice to Dave is to retire his beloved half century old DeClerc to the antiquarian book collection. Even M&BS doesn't contain a modern accounting of fusel production. My advice to brewers is to choose a different yeast if fusels give you problems. The yeast strain is a major factor in fusels. But try to keep the amino acid level appropriate (not too high or low) for the yeast growth required. You can't avoid the growth, but you could slow the rate (ferment colder for example). - -- One other related point. It's largely the growth RATE rather than the total amount of growth that matters most. Relates to the concentrations of oxo-acids in the case of fusels, and to other flavor effects too. Note that if we pitch REALLY big as in lager brewing, then 75% of the final yeast cake is new growth, if you pitch really small, as from a smack-pack, then maybe 99% of the final yeast is new growth. The difference in flavor is not likely due to the difference of 75% vs 99% new yeast growth. Adding an extra 32% (100*(99/75 -1)) of off-product doesn't give the sort of night-and-day differences that underpitching causes. === Jeremy J. Arntz asks ... >I am interested in yeast "ranching". I've been reading archives issues of >HBD about the culturing and freezing of yeast samples. These are two different things. For 'freezing' or cold storing a culture on an agar plate you should not be overly concerned about concentration of nutrients - as the growth is limited, surface and likely aerobic. For starter wort you should be very concerned about growth conditions and concentrations. >1. What should the specific gravity of the "base" wort be? > I've read 1.040, but I also believe that I've read 1.020. IMO 1.020 is fine when making up an agar plate for storage, but 1.030 or 1.040 is best for starter wort. Higher than 1.050 slows growth and know of brewers who won't repitch from even 1.055SG beer because the yeast isn't so energetic after this workout. Less than 1.030 and the sugars will form a low limit to the amount of yeast growth. >2. What recipe should be used for the wort? > Again I've read 2 Tablespoons of DME in a cup of boiling water. > What about hops? Calculate the SG by weighing rather than volume measuring the DME. Hops can have a MINOR antibacterial effect against a very few bacteria. Not only is it not worth the trouble, but it can also mask the fact that you do have infection problems in your starter media. It also could mask the off-flavors that you should be trying to smell and taste for when you separate the starter media from your yeast. IMO you should avoid hops in starters. IF you have an infection problem with your starter media the answer is to review and revise your sanitation procedures, not add bandaids. >3. I am also interested in how streaking for isolated colonies reduces or > eliminates mutations? It gives you the ability to select a colony developed from a single cell. If that cell was a mutation, the culture you grow from it will show defects like a sore thumb. Often the surface plate colony will look odd to begin with. Certain mutant, such as oxygen deficient mutations occur regularly at high rates (0.5%!) and so avoiding these means choosing culturing conditions that prefer normal growth - plating out won't help here. >4. Does anyone know of a good book on yeast propagation the is in-depth and >accurate, yet is semi-easy to read? I am especially interested in storing and >quality control. Rog Leistad has a nice little pamphlet for beginners, but the next step from there is the professional lit. Any university library should have some books intended for undergrads - perhaps labs practices manuals, that you should find very readable. Tho' they will probably not be specific to yeast, and certainly not brewers yeast. YKCK http://oeonline.oeonline.com/~pbabcock/yckco/yckcotbl.html has all of the materials you'll need and enough yeast cultures to keep you busy. The only 1stop shopping place I'm aware of for small orders. -S Return to table of contents
Date: Sat, 19 Feb 2000 14:43:41 -0500 From: "Alan Meeker" <ameeker at welchlink.welch.jhu.edu> Subject: more pitching rate Bret Morrow wrote in part: > Yeast pitching rates that get taken as gosple on HBD are > industrial-based. The goals of industrial based brewing are different > than my own. Bret, I think it is important to realize that this is only partly true. This is one of the things I was criticizing Pivo for - such black and white statements almost never apply to such a complex enterprise as brewing. We certainly share /some/ of the same goals as any large-scale commercial brewing outfit such as: Consistency Lack of off-flavors -from poor fermentation performance due to stressed yeast -from contaminating microbes getting a foothold -from autolyzed yeast Complete and timely fermentation All of these will be impacted to a significant degree by the yeast pitching rate. Of course, there are constraints on the big boys that we homebrewers aren't bound by - like the need to optimize throughput/turnaround time and optimize the use of raw materials in order to maximize profits. While these play a big part in determining something like pitch rate for the commercial guys they are still constrained by the quality factors I mentioned above. Also, saying something like "low pitching rates are fine" glosses over a number of important variables that could easily serve to negate such a simplistic statement. Things like yeast strain differences, how healthy are the pitching yeast? How well oxygenated were they during the growth of the starter (ie - how well charged in sterols and UFAs are they)? How are their glycogen levels? How well aerated is the wort they are going into? What is the SG of the wort? How's the FAN? What temp will the ferment be conducted at? What kind of beer are you trying to make? etc etc etc... All these variables and more come into play making it virtually useless to make any blanket statements regarding pitching rates. The advice to experiment within the realm of your own system is certainly good advice. I have done so and found that the closer I can get to commercial rates the better the quality of my beer. However, there are instances in which pitching rate may be a useful process variable for adjusting the final flavor of the beer. George De Piro and others have pointed out the case of Bavarian Weissens in which you can adjust the resultant ester profile by adjusting pitch rate. -Alan Meeker Lazy Eight Brewery Baltimore, MD Return to table of contents
Date: Sat, 19 Feb 2000 15:09:54 -0400 From: Aaron Perry <vspbcb at earthlink.net> Subject: contamination Cocci or not! Wyeast hasn't failed me yet !!!!!! Great brews!!!! Return to table of contents
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