HOMEBREW Digest #4627 Wed 13 October 2004

[Prev HBD] [Index] [Next HBD] [Back]

		Digest Janitor: pbabcock at hbd.org


                  Beer, Beer, and More Beer
      Visit http://morebeer.com to show your appreciation!

    Support those who support you! Visit our sponsor's site!
********** Also visit http://hbd.org/hbdsponsors.html *********

  Yeast carbohydrate consumption (Kurt Thorn)
  Fortnight of Yeast 2004 - Repitching Yeast ("Steve Smith")
  Kinetics and Thermodynamics ("Fredrik")
  Electric Brewery ("richard")
  Re: Kinetics and Thermodynamics ("Dave Burley")
  Syracuse Beer Shops (elal)
  News Scoop - National Beer Hall of Fame ("Dan Listermann")
  March Pumps ("Jay Spies")
  sequential sugar utilization by brewer's yeast (ALAN K MEEKER)

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * The HBD Logo Store is now open! * * http://www.hbd.org/store.html * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Suppport this service: http://hbd.org/donate.shtml * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Beer is our obsession and we're late for therapy! * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * A Fortnight Of Yeast * * Presented by the HBD in cooperation with Lallemand * * Questions submission: 10/11 - 10/22/2004 * * include Fortnight Of Yeast, 2004 in your subject line * * More info http://hbd.org/hbd/archive/4620.html#4620-3 * ********************************************************* 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. LOOKING TO BUY OR SELL USED EQUIPMENT? Please do not post about it here. Go instead to http://homebrewfleamarket.com and post a free ad there. 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@hbd.org or read the HBD FAQ at http://hbd.org. JANITORs on duty: Pat Babcock (pbabcock at hbd dot org), Jason Henning, and Spencer Thomas
---------------------------------------------------------------------- Date: Tue, 12 Oct 2004 23:49:25 -0400 From: Kurt Thorn <Kthorn at CGR.Harvard.edu> Subject: Yeast carbohydrate consumption Hi all - I just joined the digest after reading the archives for a while. I have one comment on the discussion about whether yeast consume carbohydrates serially or in parallel. In lab yeast strains (I suspect the same is true for brewing strains, but have no proof), if glucose is present in the media, the yeast will consume it preferentially. The presence of glucose shuts down the synthesis of the transporters for uptake of other sugars. I don't know if there is a hierarchy for other carbon sources available to the yeast, but I suspect that if so, it is a less pronounced effect. Best, Kurt Thorn Return to table of contents
Date: Tue, 12 Oct 2004 22:35:06 -0600 From: "Steve Smith" <sasmith at in-tch.com> Subject: Fortnight of Yeast 2004 - Repitching Yeast First, my apologies for such a basic question, but in my research I have noticed that some people suggest reusing yeast by pitching wort over the existing trub/yeast in a primary fermenter immediately after racking the beer that had been on it into a secondary fermenter, or by harvesting some of that yeast to use with the new batch of wort. Other people, including Wyeast and/or White Labs and John Palmer provide information for washing yeast when taken from the primary fermenter before repitching it. Or, if timing is right, it is preferable to harvest yeast from the bottom of the secondary fermenter at bottling time, or by top harvesting ale yeast as it is found in the foam during primary fermentation. I recently reused yeast for the first time. I opted to harvest a pint of yeast/trub (placed in a sanitized jar) from the bottom of the primary after racking off the all-grain beer, and repitched about half of the yeast/trub a couple days later in a different style beer that called for that same variety of yeast. The wort fermented practically over night (when I checked the gravity it had dropped to the desired level). Did I follow an acceptable practice, or am I likely to end up with off flavors in my second batch of beer off of the same yeast (consider that I used good sanitation)? I realize that autolysis could contribute to off flavors in the second batch if the yeast/trub was exposed to wort for too long a period.. I had fermented on the trub for eight days with the first batch, and plan on racking off the trub after five days in the second batch. Steve Smith Return to table of contents
Date: Wed, 13 Oct 2004 08:33:15 +0200 From: "Fredrik" <carlsbergerensis at hotmail.com> Subject: Kinetics and Thermodynamics I wanted to wait and see what the fortnight response is, but since Dave Burley posted this comment perhaps others think the same... Thanks for your comments Dave, I am not sure if I was able to explain myself properly, it's always cumbersome to isolate something without posting all definitions and math but to put it in context. I don't suggest "energy states" as in equilibrium states. As the whole thing with fermentation is all about dynamics what I meant with energy energy FLOWS. And that is indeed kinetics.So here I think I was unclear. I promise to post details on this once it's done. The simulation will attempt to model the kinetics, not equilibrium things. The model is not some "FG = f(x)". The model is a set of DEs, that requires a numerical solution/simulation. The model will contains a number of made up functions that are supposed to mimic to my understanding yeast responses on external changes. The basic stuff, like depletion of sugar and production of alcohol is done, the problem is to get the fine structure right, to model the stress factors, and the exact attenuation. This is the hard part. I need to quantify and decompose the different stress factors, and model the exact dynamic biomass yield. I don't care if it's tricky, I've already comitted to at least try. Or actually, the fact that it's tricky is the whole point. As far as I know some sugars are parallell, but some are not. glucose fructose and sucrose are I think kind of parallell. But these sugars are supposed to depress the uptake rate of maltose and maltotriose. This is (among others), according to Dr.Cone from last years fortnight. Why activate yet another enzyme system (this is a cost) when there is plenty of easy stuff left? ( Analogies: The *idea* is no more strange than the fact that a predator always aims for the weakest pray. It's certainly less of an expense to catch the weakeast pray. However when the weak prays become rare, does the fit prays become favourable as well. It doesn't make sense running around the woods for a day looking for a one-legged rabbit. ) You can't plug maltotriose nor maltose directly into the glycolysis. There is an extra step of effort to prepare maltotriose than maltose. Add to this the lower genetic affinitiy for it. Further decreasing the effiency of uptake. The balancing I suggest is between efforts and gain. I suspect the offset that causes food to be left is stress and cost of staying active. I would assume (but I may be wrong as always) that trying to extract the last food, takes a bigger effort than it gains. So it goes dormant. I think this logic is crystal clear. If I have missed something let me know. I think the hard parts is to mimic the regulation that are genetically controlled. Quantify the effect of stresses etc. This seems to be the best candidate mechanism atm. Even if it's not perfect I have to work with the best I've go for the moment. I was hoping to get some further ideas/input by posting it here. /Fredrik " TRYING is the first step towards FAILURE" - -- Homer S Return to table of contents
Date: Wed, 13 Oct 2004 22:08:57 +1000 From: "richard" <richard_beattie at optusnet.com.au> Subject: Electric Brewery Hi !! I'm in the process of graduating to all grain and am setting up the brewery now. Batch size 5 gal - and I'd like to stay indoors - so my preference is an electric brewery. I've made a mash tun from an old esky (picnic cooler) - so mashing is taken care of - but my choice for HLT and Kettle was going to be a BRUHEAT style boiler - or something equivalent - bought off the shelf. BUT - they seem to be totally unavailable in Australia now - so only option is to convert some plastic buckets. A very kind Home Brew shop in Melbourne gave me the tip off to use a cheap electric kettle and pull the element out. I brought 2 from a large department store for under A$10 and they look like they will do the job. 2400W at 240V. The elements are actually shiny metal. Has anyone else used something similar? Any tricks for new players?? Any feedback much appreciated before I start to install. Also - anyone in OZ know a good supplier of plastic buckets. 20L ones seem easy to get but I'm looking for a 30L bucket for the kettle. Cheers. Richard Sydney Australia Return to table of contents
Date: Wed, 13 Oct 2004 09:33:28 -0400 From: "Dave Burley" <Dave_Burley at charter.net> Subject: Re: Kinetics and Thermodynamics /Fredrik, >( Analogies: >The *idea* is no more strange >than the fact that >a predator always aims for the >weakest pray. It's certainly less >of an expense to catch the >weakeast pray. However when >the >weak prays become rare, does >the fit prays become favourable >as well. It doesn't make sense >running around the woods for a >day looking for a one-legged >rabbit. ) Don't anthropromorphisize the yeast into a predator. Think of yeast as a catalyst promoting a chemical reaction ( which energetically is possible, but not kinetically rapid) via their enzyme and transport mechanisms. The yeast do not wait or make energy decisions or look for the weakest "prey". If you were to start with all the same concentrations of carbohydrates and look at the fermentation as it proceeds you will find some carbohydrates are disappearing more quickly and the final result may be there are certain carbohydrates left depending on many different conditons of the fermentation as well as the yeasts' genetic makeup. Point is, all of these carbohydrate reactions are proceeding at the <same time>, <NOT serially>, as you suggest in your comments. Some are just slower than others. As you commented, there are some secondary interactions due to the "interference" of certain sugars, but the point is all of these reactions are going on simultaneously Change your concept and model and it will more closely fit reality. Keep on Brewin' Dave Burley Return to table of contents
Date: Wed, 13 Oct 2004 11:14:45 -0300 From: elal at isn.net Subject: Syracuse Beer Shops Thanks to the excellent assistance of HBDers, I discovered the delights of two beer shops in the Syracuse, NY area which is about two hours drive from me here in Kingston Ontario. Galeville Grocery: http://www.genx40.com/archives/2004/august/galeville Party Source: http://www.genx40.com/archives/2004/october/partysource If anyone has any other upstate New York shops to check out, please let me know. I know that Buffalo and Rochester has one great one each that I intend to check out sooner or later but how about Utica or Rome or Albany? Any assistance with my quest for beer shopping heaven is appreciated. - -- Alan www.genx40.com Return to table of contents
Date: Wed, 13 Oct 2004 14:53:44 -0400 From: "Dan Listermann" <dan at listermann.com> Subject: News Scoop - National Beer Hall of Fame The people from the US Beer Drinking Team just called to tell me that the National Beer Hall of Fame will be located in Cincinnati very near the Downtown Convention Center in about 100,000 sq ft of prime commercial space. Projected opening date 9-06. Too cool! We will see if it comes about! Dan Listermann Return to table of contents
Date: Wed, 13 Oct 2004 15:11:32 -0400 From: "Jay Spies" <jayspies at citywidehomeloans.com> Subject: March Pumps All - Martin Brungard makes some interesting observations regarding the orienting of March and other mag drive pumps..... >>>I just checked the March website and confirmed that they specifically say that their pumps must be mounted horizontally. I have been into my March pump and can attest that they only have simple thrust washers at the shaft ends. They would not perform well in a vertical configuration.<<< Yikes! I know that many people here on the HBD, as well as B3 (sponsor of the HBD) use these pumps vertically mounted. I wonder if any other people can chime in who have them mounted vertically (or otherwise) who've had long-term experience with a non-horizontal configuration... Any pump failures/mishaps? I have 2 of these pumps and they're mounted horizontally, but that was by pure happenstance.... Jay Spies Head Mashtun Scraper Asinine Aleworks Baltimore, MD Return to table of contents
Date: Wed, 13 Oct 2004 16:51:35 -0400 From: ALAN K MEEKER <ameeker at mail.jhmi.edu> Subject: sequential sugar utilization by brewer's yeast In response to Fredrik's query Dave Burley wrote: "Perhaps part of the problem is /Fredrik's concept that somehow the yeast take in and consume carbohydrates serially. Not so. All the carbs are being processed in parallel. Some just more slowly than others." Actually, brewer's yeast do in fact utilize sugars in a sequential manner. Fructose and glucose are utilized first (Even though they are lower abundance wort sugars), before any appreciable processing of the major malt sugars, maltose and maltotriose, occurs. This makes perfect sense from the yeast's point of view because glucose and fructose are the 'easiest' sugars to use from a metabolic efficiency point of view. Maltose and maltotriose must first be converted to glucose (hydrolysis of these sugars liberates glucose) before this can be plugged into the metabolic pathway(s). Underlying the mechanics of this sequential utilization phenomenon are the specific transporter proteins that bring the sugars into the cell. It is not the case that all the transporters for all the various sugars are synthesized and present on the cell surface at all times. Such a situation would be energetically wasteful and would have been selected against during evolution. Instead, for reasons of efficiency, the yeast use the easiest substrates first, particularly glucose. In fact, when glucose is present the yeast cell actively shuts down any production of the proteins that are involved in the transfer and breakdown of maltose and maltotriose. This is why there is a delay in maltose/maltotriose uptake and metabolism; there are no transport proteins on the cell to bring these particular sugars in. It is not until the glucose has been exhausted that the maltose utilization genes are freed from glucose repression. -Alan Meeker Return to table of contents
[Prev HBD] [Index] [Next HBD] [Back]
HTML-ized on 10/13/04, by HBD2HTML v1.2 by KFL
webmaster@hbd.org, KFL, 10/9/96