HOMEBREW Digest #4329 Fri 22 August 2003

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  priming lagers (HOMEBRE973)
  Sigh. Another worm... (Pat Babcock)
  RE: Sanitizers and Septic ("Bridges, Scott")
  CO2 being poisonous (Ed Benckert)
  Water composition affecting Cold Trub formation? (FRASERJ)
  Dr. Cone 2003 ("Sweeney, David")
  CO2 tank safety (Calvin Perilloux)
  unknown hops (Peter Collins & Sara Wilbur)
  Re: How much priming sugar per bottle ("Tracy P. Hamilton")
  DO Concentrations (mabrooks)
  "waxy" starches (sedam)
  anti-foam ("Kevin Kutskill")
  Dr. Cone Responds- Yeast Flavours- Denny Conn ("Rob Moline")
  BeerSmith 1.1 Software Released ("Brad Smith")
  Dr. Cone Responds-Yeast Flavors-Steve B ("Rob Moline")
  Dr. Cone Responds-Yeast for very high-gravity beers-Al Korzonas ("Rob Moline")
  Dr. Cone Responds-Lager Pitching Temperature-David Lamotte ("Rob Moline")
  Gump and Knowing It All ("Rob Moline")

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * The HBD Logo Store is now open! * * http://www.hbd.org/store.html * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Beer is our obsession and we're late for therapy! * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * IN PROGRESS! * * * * * * * * * Dr. Clayton Cone Fortnight of Yeast * * 8/11/03 - 8/22/03 Yeast Questions Answered * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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 cannot reach you. We will not correct your address for the automation - that's your job. HAVING TROUBLE posting, subscribing or unsusubscribing? See the HBD FAQ at http://hbd.org. 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 or read the HBD FAQ at http://hbd.org. JANITOR on duty: Pat Babcock (janitor@hbd.org)
---------------------------------------------------------------------- Date: Thu, 21 Aug 2003 10:34:55 -0400 From: HOMEBRE973 at aol.com Subject: priming lagers I am curious what is the general view on priming lagers (beers that have actually lagered at 32 F). Do most people let the beer warm to room temperature, then prime? Do you store the primed beer at room temp. or between 50 and 60 F, which was the fermentation temp? Thanks, Andy in Hillsborough Return to table of contents
Date: Thu, 21 Aug 2003 11:41:42 -0400 (EDT) From: Pat Babcock <pbabcock at hbd.org> Subject: Sigh. Another worm... Greetings, Beerlings! Take me to your lager... Folks, my apologies regarding the variable Digest timing of late. The servers are spending the majority of their time processing the product of those who have nothing better to do than write worms and viruses - to the extent that there is little processor time left for much else. Bear with. I am manually triggering Digests when I see the gap. On a positive note, the mail coming in indicates that a bunch more ISPs are filtering such rot at their doorstep. This should mitigate a lot of the traffic the worms generate. Next, they should set their mail systems to simply quietly kill viruses, rather than respond back to the falsified address. This would reduce the traffic to the minimum... - -- - God bless America! Pat Babcock in SE Michigan pbabcock at hbd.org Home Brew Digest Janitor janitor@hbd.org HBD Web Site http://hbd.org The Home Brew Page http://hbd.org/pbabcock [18, 92.1] Rennerian "I don't want a pickle. I just wanna ride on my motorsickle" - Arlo Guthrie Return to table of contents
Date: Thu, 21 Aug 2003 11:46:44 -0400 From: "Bridges, Scott" <ScottBridges at sc.slr.com> Subject: RE: Sanitizers and Septic Sorry lost the original posters name.... >>Does anyone have information on using >> sanitizers and it's effect on the septic system? I'm hoping that the >> relatively small amounts I use for five gallon batches once a month or so >> shouldn't be too detrimental. > >I do not have some sort of authoritative study where people threw iodophor >in their septic system and studied the results, but it's pretty easy to see >the scope without even crunching the real numbers. > >If you are mixing iodophor to taste-free sanitizing levels, and then pouring >that dilution into a septic tank of several hundred gallons, you are again >diluting this so low that the few organisms you might kills off will >regenerate within minutes, if not seconds. I don't have any studies either, just personal experience. I've lived in a house with septic tank for the last 17 years. I've been brewing with various degrees of regularly for almost 15 yrs. I've gone back and forth with numerous brewing cleaners and sanitizers along with regular laundry and dishwasher detergents. I've never had a problem. YMMV. Scott Return to table of contents
Date: Thu, 21 Aug 2003 12:02:13 -0400 From: Ed Benckert <ed at ebonmists.com> Subject: CO2 being poisonous Tanksalot said: I don't believe there would be a "rocket" flying around your brewery. CO2 is the gas used in many fire extinguishers so it's not poisonous or flammable. No, not flammable, but very very dangerous. Heres a link to a MSDS (Material Safety Data Sheet) on CO2: http://www.hoopersupply.com/msds/co2.htm You dont need to be in a pure CO2 environment to suffocate and die (as is obvious). It IS poisonous in concentrations. Ever stick your head in your fermenting bucket and take a sniff of the beer, forgetting that theres a blanket of CO2 on it? I have. Burns your sinuses out, tears your eyes up as you vision goes dark for a second. I've done it. Thats not from not inhaling oxygen, it's from the CO2 messing with your system. Return to table of contents
Date: Thu, 21 Aug 2003 12:36:16 -0400 From: FRASERJ at Nationwide.com Subject: Water composition affecting Cold Trub formation? I moved from Westerville, OH to Pickerington, OH. Each had its own water supply. Since I moved, I have noticed that I no longer get a thick formation of cold trub after the counter chilling. How does water chemical composition affect trub formation? Is there a general rule of thumb on what I should add to my water to get my trub back (its affecting my beers clarity after fermentation)?? John M. Fraser Return to table of contents
Date: Thu, 21 Aug 2003 12:16:21 -0500 From: "Sweeney, David" <David at studentlife.tamu.edu> Subject: Dr. Cone 2003 Dr. Cone: My brain is about to explode with all of the biochemistry (they don't call it BICH for nothing!). I took it in college but try not to think about those horrible days. In Fix's book _Principles of Brewing Science_, George outlines a list of the most critical controllable elements of the brewing/fermenting process for homebrewers, for example, fermentation temperature, pitching volume, etc. Since I is a Aggie, I have trouble with lists larger than I can count on one hand. So my question is this: What are the top five controllable variables (in order of importance) with regard to yeast for the homebrewer? David Sweeney Texas Aggie Brew Club (TABC) Millican, Texas david at studentlife.tamu.edu [1067.2 mi, 219.8 deg] (Apparent) Rennerian Return to table of contents
Date: Thu, 21 Aug 2003 10:56:18 -0700 (PDT) From: Calvin Perilloux <calvinperilloux at yahoo.com> Subject: CO2 tank safety "Tanksalot" wrote about the dangers of CO2 tanks: >> Two years ago I had some 2.5# and 15# tanks refilled, >> and foolishly left them in the trunk of my car... Yow, I bet that was fun! I seem to remember that the safety release vales are supposed to release gas (much!) slower than a catastrophic decapitation, so no rocket effect for you, sadly, just Little Ice Age in the boot! I bet any bystanders were much impressed! (grin) On that note, I also read from some vague source that CO2 is less prone to the "rocket" effect because unlike nitrogen and many other common compressed gases, CO2 is in liquid/gas form in the cylinder, and the evaporation of the liquid provides a dramatic chilling effect and reduction of vapour pressure which attenuates the explosive evacuation effect. While that might sounds reasonable, the source did not mention the degree of this effect. Enough to reduce any damage substantially, or just a few insignificant percent? >> [CO2] is the gas used in many fire extinguishers so it's >> not poisonous or flammable. It's not flammable, and not *AS* poisonous as things like chlorine, but it is poisonous when present in amounts over a few percent. I think a Google check might find the official safety levels somewhere. I do know that when we converted our IT shop some years ago from R-12 fire suppression to CO2, we had some intense instruction on the risks. Unlike R-12, argon, or nitrogen, which simply displace air, CO2 in high concentrations can dissolve into your blood and cause some effects ranging from unpleasant to dire. But you're right, a whiff of even concentrated CO2 won't hurt you, er, except the pain from those stinging nostrils! Meanwhile, Keith Lemcke hopes for the day when we won't have CO2 tanks but will get bulk delivery, similar to heating oil, perhaps? >> I hope any & all service establishments who change CO2 tanks >> frequently will eventually move to bulk CO2 storage, which >> uses a lower pressure stationary CO2 tank that is filled >> from a bulk truck right at the service environment. Fine for establishments that use a lot of gas, and I know Keith isn't advocating that we homebrewers shift to such a system (or I hope not), but let's hope that it's a not a big trend that eventually makes CO2 standard delivery a large-scale thing and filling of smaller tanks lots less profitable. Sometimes it's hard enough for inidividuals to get tanks refilled as it is. Calvin Perilloux Middletown, Maryland, USA Return to table of contents
Date: Thu, 21 Aug 2003 14:19:22 -0400 From: Peter Collins & Sara Wilbur <sarapete at sympatico.ca> Subject: unknown hops Hi everybody, I have some hops that a friend of mine gave me from his garden and he is not sure what variety they are. Is there any way to tell their variety by looking or smelling? Also, I have had them zip-locked in the freezer for almost two years, are they still good? My initial plan was to use them for dry hopping a pale ale but if there are other better uses for them I am open to suggestions. Thanks for your time. Peter Collins Cambridge, Ontario Return to table of contents
Date: Thu, 21 Aug 2003 13:52:01 -0500 From: "Tracy P. Hamilton" <hamilton at uab.edu> Subject: Re: How much priming sugar per bottle A real simple rule holds: If a 5 gallon recipe calls for 3/4 cup priming sugar, use 3/4 teaspoon for a 12 oz. bottle. The reason this works is that 1 cup has 48 teaspoons and one batch has 48 12 oz. bottles. Adjust appropriately for different size bottles, or for different carbonation levels. 1 tsp for a Grolsch 16 oz bottle, for example. Or 1 teaspoon in 12 oz bottle for a hefeweizen. Tracy P. Hamilton Birmingham Brewmasters Return to table of contents
Date: Thu, 21 Aug 2003 12:13:34 -0700 (PDT) From: mabrooks <mabrooks12 at yahoo.com> Subject: DO Concentrations Date: Wed, 20 Aug 2003 09:53:19 -0400 From: Cairns Jim MTPROUS <Jim.Cairns at mt.com> Subject: Re: Do levels Date: Tue, 19 Aug 2003 12:20:27 +0000 From: "A.J. deLange" <ajdel at cox.net> Subject: DO Levels Gentlemen, One could always use the "Winkler Method" (circa 1888) of D.O analysis. It utilizes additions of divalent manganese and a strong alkali, results can be determined either visibly or via electrometric end point. Though not many analysts are familiar with this method, it is by far the most precise method available for determination of DO. I used this method on water samples years ago when I was in Grad school and believe me it is tedious. Come to think of it, I may just use it during my Fall water chemistry course instead of the all too cheap and easy method of the "Membrane probe". Wont the grad students love that! Matt B. Northern VA. Return to table of contents
Date: Thu, 21 Aug 2003 17:34:29 -0400 From: sedam at email.unc.edu Subject: "waxy" starches Clarifying point on starches...what can I say...I can't resist. There have been a couple of posts lately talking about "waxy" potatos and the wax/oil content of that and other starches. There's a bit of a nomenclature issue here, althought the content of the previous posts (mostly in yesterday's HBD) were spot on. Starch chemists (geeks that we are) use the term "waxy" to refer to grains/tubers having high amylopectin content. So you can have waxy corn, waxy potato, waxy rice, etc. None of these have excessive amounts of wax or oils. Just that if you analyze the starch content they'll usually have >95% amylopectin. I suppose they're called waxy because when you gelatinize the starches they will tend to "set up" firmer than the high amylose starch grains. Who knows...never trust a cereal chemist with marketing. As an aside, the high amylose starches are often refered to as "Hylon" starches...although this is the trade name of a corn hybrid from my former employer. Starchily yours, Marc - -- Marc Sedam Chapel Hill, NC Return to table of contents
Date: Thu, 21 Aug 2003 18:40:25 -0400 From: "Kevin Kutskill" <beer-geek at comcast.net> Subject: anti-foam Brian from Winnipeg mentions: >Hop Tech must love you if you are using it up at that rate. I found 1/4 tsp >of their product was lots, sometimes all it took was a few drops. It depends >largely on the wort and yeast. I've switched to FermCap now. Picked up a >lifetime supply from a defunct brew pub for a pittance. Call me the anal brewer. Hop Tech's directions state 1 tsp. per 5 gallons. Didn't think on trying less (which I will for the next brew session). It is nice to not worry about blow off tubes, though. I was originally looking for a source for FermCap, when I found Hop Tech's Foam Control. Anyone out there know of a good source for FermCap for a homebrewer? Kevin beer-geek at comcast.net Return to table of contents
Date: Thu, 21 Aug 2003 21:00:15 -0500 From: "Rob Moline" <jethrogump at mchsi.com> Subject: Dr. Cone Responds- Yeast Flavours- Denny Conn Dr. Cone Responds- Yeast Flavours- Denny Conn Dr. Cone, First, thank you so much for giving us some of your time. My question concerns yeast growth as it relates to flavors in beer. I have read several articles mentioning that yeast growth is important to flavor production in beer, and that the amount of yeast growth is related to the amount of yeast pitched. My own completely unscientific experiments have lead me to believe that I produce more "interesting' beers when I, for instance, repitch only part of the yeast slurry from a previous batch rather than the entire amount. The conventional wisdom in the homebrew world seems to be to use the entire previous slurry to produce short lag times. Is there a relationship between yeast growth and the flavors produced in beer? Is it better to pitch an entire previous yeast slurry, or is there a benefit to using a large, but not entire, amount of slurry? I apologize for the vagueness of the question, but I have no way to quantify the exact amounts I've been using. It's simply either "all" or "part". Thank you again. Denny Conn Denny Conn, Ester and other flavor component production or synthesis is a complex subject because there are so many variables taking place at the same time. You are right, ester production is related to yeast growth but not in the way you might think. The key element to yeast growth and ester production is acyl Co-A. It is necessary for both yeast growth and ester production. When it is busy with yeast growth, during the early part of the fermentation, it is not available for ester production. Ester production is directly related to biomass production. Everything that increases biomass production (intensive aeration, sufficient amount of unsaturated fatty acids, stirring) decreases ester production. The more biomass that is produced the more Co-enzyme A is used and therefore not available for ester production. Anything that inhibits or slows down yeast growth usually causes an increase in ester production: low nutrient, low O2. It has been noted that a drop in available O2 from 8 ppm down to 3 ppm can cause a four fold increase in esters. Stirring in normal gravity decreases ester production. Stirring in high gravity increases ester production. CO2 pressure in early fermentation decreases ester production. Taller fermenters produce less esters than short fermenters. High temperature early in fermentation decreases ester production. High temperature later in fermentation increases ester production. Low pitching rate can result in less esters. There are other flavor components such as higher alcohol that have there own set of variables. Stirring increases production of higher alcohols. CO2 pressure does not effect the production of alcohol. Amino acid levels in the wort effect the production of higher alcohols. Most of the higher alcohol is produced during the growth phase (exponential phase) of the yeast. I am sure that there are many other variables. I am also sure that there are beer makers that have experienced the very opposite with each of the variables. Pitching rates depend on several factors: (1) The speed in which you wish the fermentation to take place. Some professional brew master are in more of a hurry than others; desired beer style, shortage of fermenter space. Pitching rates would vary as a means to increase or decrease the total fermentation time. 10 X 10/6th cell population for normal fermentation rates. 20 X 10/6th or more for a quick turn around. (2) Temperature control. If lack of refrigeration is a problem, the fermentation needs to be spread out over a longer period by pitching with less yeast. (3) Health of the pitching yeast. If the pitching yeast has not been stored under ideal conditions (4C for less than one week) then larger pitching rate must be done to compensate for the deteriorate of the yeast. Increased pitching rates has its limits in trying to compensate for poor storage conditions. (4) When all other variables are under control you can use variations in pitching rates to achieve certain flavor profile that are of interest to you. Conventional wisdom regarding pitching rate can lead to problems. During each fermentation cycle the yeast will increase in size about three times, so if you use all the yeast from the previous batch you will soon be pitching with a huge amount of yeast. Professional brewers usually re-pitch with about 25% of the yeast from the previous batch. Proper handling of the yeast during storage (4C and <7 days) will minimize any problem with long lag phase. Start with a fresh culture of yeast after about five recycles for bacteria control and or after 10 - 15 cycles for genetic drift purposes. There are many who will say that they are proud of the fact that they have used the same yeast after over 100 cycles. More power to them. I wish that I could explain their luck. Good practices suggest frequent renewal with a fresh culture is a good policy. Thank you for your very good question. Clayton Cone - --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003 Return to table of contents
Date: Thu, 21 Aug 2003 22:12:58 -0400 From: "Brad Smith" <beersmith at beersmith.com> Subject: BeerSmith 1.1 Software Released I'm pleased to announce that BeerSmith 1.1 has been released. Its a very cool piece of brewing software with all of the features a home brewer or professional might expect... View the features and download a trial version at: www.beersmith.com Thanks! Brad Smith Return to table of contents
Date: Thu, 21 Aug 2003 21:21:33 -0500 From: "Rob Moline" <jethrogump at mchsi.com> Subject: Dr. Cone Responds-Yeast Flavors-Steve B Dr. Cone Responds-Yeast Flavors-Steve B If this is a naive question please forgive, but what is unique about the different strains of yeast that would allow them to create/impart different flavors? Is it something with the biological make-up of a particular strain or some other native charachteristic to yeast metabolism? As a follow-up can the yeast organism be sufficiently isolated to "breed" for particular flavor profiles? Thanks S Steve, This is a very complex subject that genetices and other researchers are only beginning to understand and believe me, I really have only a rudimentary understanding of what is going on inside the yeast cell. It is in the genetic make up of each strain. Each strain does almost the same thing as another strain (of the same specie). However over the eons of time each strain has had to express certain enzyme systems over others in order to cope with its particular environment: nutrient source, climate etc. With millenniums of time, these slight changes in the enzyme systems have become permanente fixtures in its genetic make up. These slight changes give you the rich variations in flavor by-products from strain to strain; the different abilities to handle the sugars especially maltotriose in the wort; the ability to function better at cool or warm environments; etc and etc. Many thousands of strains are in nature waiting to be discovered. It is up to interested parties (brewers, winemakers, bakers, researcher etc.) to go out looking for them. Pardon my clumsy way of explaining the various strains. These various strains can be identified only by DNA fingerprinting. The different genus, species and strains can and are isolated and can and are being breed or mated. With out much success. First, there are so many different strains in nature with all the wonderful characteristics that we are looking for that screening nature seems simpler than breeding. Breeding or mating can be done but it is not always simple. Some yeast are made to sporulate. The spores of different strains or species with favorable fermentation characteristics are mated. The off spring sometimes carry the best of both strains but often time they also carry undesirable weakness of one of the strains; slow fermentation rates, H2S production etc. Often times they change after several generations. The problems are the same with the fusion technique. The cell walls of two different genus are dissolved and the cytoplasm, nucleus and DNA of each are mingled. The resulting off spring can carry the best of each parent but more often carry bad luggage from one of the parents. They often do not remain stable after several to many generations. Genetic engineering is the most promising approach to producing a designer yeast that will produce the ideal beer, but at this time our society will not accept this approach. Breeding is OK. GMO is not. Thanks for your good question. It was not easy to answer. Please ask more if my answer still leaves you puzzled or whets you appetite for more information. Clayton - --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003 Return to table of contents
Date: Thu, 21 Aug 2003 21:32:22 -0500 From: "Rob Moline" <jethrogump at mchsi.com> Subject: Dr. Cone Responds-Yeast for very high-gravity beers-Al Korzonas Dr. Cone Responds-Yeast for very high-gravity beers-Al Korzonas Dr. Cone-- When making a Barleywine or Doppelbock or Imperial Stout, is it better to use the entire yeast cake from a previous batch of lower-gravity beer or is it better to use just part of that yeast cake (half? 1/3? 2/3?) so that there is some growth? In a related question, I've read that a significant portion of the esters are produced in the growth phase. Can you confirm or correct this assertion and comment on whether strong lagers may benefit from a larger pitching rate for *this* reason? Thanks. Al Korzonas Al, From some of my replies to other inquiries, you have probably gathered that subject of pitching rate and flavor formations is very complex. Usually you have to pitch at a higher rate for high gravity beers. The general rule of thumb regarding pitching rate is one million yeast cells per ml. wort per degree Plato. This is a good guideline if you have good yeast storage and handling practices: 4 C. for <7 days. As you deviate from these conditions it would be wise to increase the pitching rate a little. If you have an accurate way to measure the yeast population and vitality in your yeast cake great. If you do not, then I would start with 1/2 of the cake the first time then adjust up or down as needed the next time. The opposite of what you read is usually true regarding the increase in ester production during the growth phase. During the growth phase the ester production is reduced because acetyl-CoA is used for yeast growth and not available for ester production. Higher pitching rates will result in higher ester formation because there is less growth before they reach the stationary phase. Higher pitching rates are also required for the yeast to reach complete attenuation. Higher gravity wort is less friendly to the yeast than low gravity wort. Also, the higher the initial gravity the higher is the ester production because there are in general more metabolites produced that can react with each other. Thanks for your good question. Clayton Cone - --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003 Return to table of contents
Date: Thu, 21 Aug 2003 21:39:35 -0500 From: "Rob Moline" <jethrogump at mchsi.com> Subject: Dr. Cone Responds-Lager Pitching Temperature-David Lamotte Dr. Cone Responds-Lager Pitching Temperature-David Lamotte Dr. Cone, I would like to add my thanks to you for your generous contributions, and to the previous posters for their thoughtful questions. From previous discussions on the HBD and a number of brewing texts, there appears to be two schools of thought regarding lager yeast pitching temperatures. One suggests that you pitch a lot of yeast at or below the fermentation temp (8-12C) in order to minimise that amount of esters etc produced. The other suggests that you pitch the normal amount at ambient room temperature and begin cooling down to your fermentation temperature once the first visible signs of fermentation begin. My concern with the second method is that the fermentation will proceed at too high a rate unless you have a large 'cooling power' available. Do you have any information on the effect that pitching temperature has on lager fermentations. Thanks again, David Lamotte Fermenting in Newcastle, NSW, Australia David, You are right to be concerned about controlling the temperature of a fermentation if you do not have adequate refrigeration. The higher temperature generates heat faster and must be removed to keep the fermentation from getting out of control. Usually the higher the fermentation temperature the higher the ester formation. However, the more yeast growth that you have at the higher temperature the less acetyl-CoA is available for ester formation. So higher temperature at the beginning produces more yeast and less esters while higher temperatures during the stationary phase produces more esters. I am not sure that pitching a lot of yeast in order to minimize ester production is actually what happens. The lower pitching rate should give you less esters. Acetyl-CoA is necessary for yeast growth and ester production. When it is tied up in yeast growth it is not available for ester production. The total amount of new yeast produced is dependent on pitching rate. The lower pitching rate will produce more total yeast before it reaches the stationary phase than the high pitching rate. The final yeast population will be almost the same for both pitching rates. I am including some comments and references from my colleague Dr. Tobias Fischborn, a researcher at Lallemand research center and also on staff at Siebel Brewing School, just to give you some idea how complex the subject of esters , higher alcohol and other flavor components is. Tobias' comments: As always things are more complicated that they should be: Esters usually decrease with higher biomass production because acetyl-CoA is used for yeast growth (lipid synthesis). (Rose & Harris, Narziss, Kunze). But low nitrogen concentration also decreases ester production although less yeast is produced. In a high adjunct wort where the ratio fermentable sugar to assimilable nitrogen (C:N ratio) is high assimilable nitrogen is the limiting factor, excess yeast metabolites do not accumulate and so ester syntheses is lower. In 100% malt wort the C:N ratio is low, oxygen is the limiting factor and when growth ceases assimilable nitrogen is still abundant and yeast metabolites, including acetyl-CoA accumulate intracellularly and stimulate ester formation. (Rose, A.H. & Harrison,L.S.: "The yeast" Vol. 5, p. 43) Fusel alcohols: Anything that stimulates yeast growth causes an increase in the fusel-alcohol concentration in the fermenting wort. (Rose, A. H. & Harrison,J. S.: "The yeast" Vol. 5, p. 34). Low nitrogen content increases fusel alcohol production. In all 3 books they do not talk about pitching rate but other growth stimulating factors like oxygen, high concentration of unsaturated fatty acids and sterols. I agree that these are more important then pitching rate (only for this reason): If you have a low pitching rate and sufficient amount of oxygen you will oxygen you have the contrary effect that you will produce more esters compared to a higher pitching rate because you have more nutrients "available per cell" and the yeast is accumulating acetyl-CoA which stimulates ester formation. On the other hand if you have a very high pitching rate you have only limited yeast growth because you have only a certain amount of oxygen, usually 8 mg/L, which is used very quickly by the large amount of yeast; so most of the acetyl-CoA is not used for yeast growth. Unless you aerate during the fermentation, which you should not do, you will have more esters produced. Higher pitching rates are also associated with higher organic acid and acetaldehyde production. (Narziss,L.: "Abriss der Bierbrauerei", p. 211) Other than that pitching rate is still very important. You do not want to under pitch for various reasons. ----Tobias Fischborn Thank you for your interesting question. Hope that my answers stimulat you to ask more. Clayton Cone - --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003 Return to table of contents
Date: Thu, 21 Aug 2003 21:55:33 -0500 From: "Rob Moline" <jethrogump at mchsi.com> Subject: Gump and Knowing It All Gump and Knowing It All Now, Dave, anyone who knows me, I mean, really...REALLY (wink, wink!) knows me....like YOU know me, Dave.....knows... "The More I Know About Beer, The More I Realize I Need To Know More About Beer!" Gump! From: "Dave Burley" <Dave_Burley at charter.net> Subject: Gump and knowing it all Brewsters: Gump says he refuses to call me to inform me that he doesn't know it all. At least that's what I think he meant. {8< ) - --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.512 / Virus Database: 309 - Release Date: 8/19/2003 Return to table of contents
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