HOMEBREW Digest #3530 Mon 15 January 2001

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  Computers in HB & the Wonder of the Steam Age (Tom smit)
  Oops & steam age (Tom smit)
  Pumps ("Bill Frazier")
  Dropping time (Tom smit)
  Peristaltic pump source ("Fred L. Johnson")
  dry sanitizing + tasting notes (Smallaxe27)
  Looking for Pyramid Snowcap Clone ("Bernd Neumann")
  Eighth Annual America's Finest City Homebrew Competition ("Peter Zien")
  Resources needed (Ray Kruse)
  Homemade Peristaltic Pump (Ken Schwartz)
  Speaking of Andy Walsh ... (Demonick)
  RE: Recirculation problems with RIMS (Paul Shick)
  Phil's bottom and polypropolyene ("Eric Ahrendt")
  Re: Peristaltic pump source ("Sean Richens")
  fermentation cabinet (Doniese)
  Bad Boy On Holidays ("Helen Pay")
  Re: 6% alcohol limit (Jay Pfaffman)
  HSA is good for beer? (Jim Adwell)
  Yahoo! Finance Story - Yahoo - StarLink contamination found in beer ingredient-FDA (Yahoo! Finance)
  re: dropping  (aeration really) ("Stephen Alexander")
  Dishwashing scum ("William Graham")

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---------------------------------------------------------------------- Date: Sat, 13 Jan 2001 17:30:57 +0000 From: Tom smit <tom at lunica-data.com.au> Subject: Computers in HB & the Wonder of the Steam Age Hi all, First, a question. Does anyone know of a decent HB software program for Macintosh computers? (Other than Brewmeister) Does anyone use a computer to *do* something to or with their homebrew? I mean monitor temperature or flow rate and turn heating or cooling or pumps on and off, or even just to track the length of a mash or boil and remind you to step the temp up for the next stage of a step infusion or dedoction mash? Reading G Wheeler & Protz's books about homebrewers not having the time to attend frequently to their brews throughout the night & day I thought of how cheap a computer of only 3 or 4 years ago can be picked up for a song. I bought an old Macintosh IIci (a '386 equiv machine) into which I can plug some Analog to Digital (& D to A) boards. Using these in my home brewing definitely intrigues me. *** DAYDREAM MODE _ON_ ***. If Yorkshire yeasts make such great beers surely someone can create the HB equivalent of a Yorkshire Stone Square & build in a few switches etc to let this run with only occasional human supervision? *** DAYDREAM MODE _OFF_ *** The gadget freak within me reads posts/sites re RIMS/HERMS etc avidly. Surely that is a dead certainty for computerisation??? Cheers Tom Smit Tiny Horses Brewery Return to table of contents
Date: Sat, 13 Jan 2001 17:33:50 +0000 From: Tom smit <tom at lunica-data.com.au> Subject: Oops & steam age Pressed Send key too soon. Somebody mentioned that they use steam for increasing mash temps. Sounds like a good idea to me. Could the poster kindly email me with a few more details of his Wonder of the Steam Age? Cheers Tom Smit Tiny Horses Brewery Return to table of contents
Date: Sat, 30 Dec 2000 14:54:06 -0600 From: "Bill Frazier" <billfrazier at worldnet.att.net> Subject: Pumps Sean Richens wants a peristaltic pump but finds the prices a bit high. Sean, I busted my rib cage back in 96 and faced an end to my brewing (lifting carboys was out of the question). So, I bought a peristaltic pump from Barnant Company for about $300.00. It's a complete unit with speed control that can pump over 2 liters per minute so you can empty a carboy in less than 10 minutes. Probably the best brewing money I've spent not even considering my old injury. I use this thing every time I brew or make wine. Now if you don't want to spend the $300 call up Barnant and talk to one of their engineers. They are very helpful. Just tell them what you are doing and they will fix you up. I'm sure you can just buy the pump head and hook it up to an electric motor you might have or could acquire. Shouldn't be too hard and the price should be well under $100. I've found that you do have to use Barnant tubing. The local hardware tubing can't handle the stress of the rotors and ruptures. I get over a year out of Barnant tubing. Of course you already know the beauty of peristaltic pumps. Nothing touches the wort or beer except the inside of tubing that fits in the pump, which is easy to sanitize with iodophor. Sounds like I'm a salesman for Barnant but I just like their pump. Barnant Company phone in the US or Canada 800-637-3739. Web site <http://www.barnant.com>. Email <barnant at mc.net> Regards, Bill Frazier Olathe, Kansas Return to table of contents
Date: Sat, 13 Jan 2001 19:01:17 +0000 From: Tom smit <tom at lunica-data.com.au> Subject: Dropping time Glen makes a good point re Dr Cone's 14 hr dropping schedule > Dr. Cone had much useful knowledge to share and I'm sure a lot of it came > from the commercial manufacture of beer, not a homebrewer's scale. G Wheeler in "Home Brewing" states that commercial conical fermenters can 'ferment a typical beer in 48 hours' In homebrew we should therefore drop rather later, especially those of us doing only 5gal batches. I guess this is when foam has just covered the top of the wort, or 24 hours? Tom Smit Tiny Horses Brewery Return to table of contents
Date: Sat, 13 Jan 2001 04:54:08 -0500 From: "Fred L. Johnson" <FLJohnson at worldnet.att.net> Subject: Peristaltic pump source Sean Richens is looking for a peristaltic pump that won't cost him an arm and a leg. I have found (and purcharsed) Masterflex pumps at LabX.com for a small fraction of their cost new. You can also find other brands here also. Another potential source is your local university's surplus warehouse. (I love these places.) I have used Masterflex pumps for many years and have never had a problem with them. (No affiliation.) You can also get new ones from Cole-Parmer, who unlike some other big scientific supply houses will set up an individual account for you. Oh, and most importantly, Masterflex pumps use a large variety of interchangeable pump heads. Most of the older Masterflex pump heads are designed to use only certain size tubing, so you choose a pump head depending upon the range of flows that you will need to achieve. Masterflex now makes additional pump heads which will accept many tubing sizes. If you do purchase a Masterflex with an older style pump head (which is likely if you're picking one up second hand), you really should use the tubing designed for these pumpheads, which is also available from Cole-Parmer, of course. You can check all this out at Cole-Parmer's website, although a regular paper catalog is much quicker to use. - -- Fred L. Johnson Apex, North Carolina USA Return to table of contents
Date: Sat, 13 Jan 2001 10:04:02 EST From: Smallaxe27 at aol.com Subject: dry sanitizing + tasting notes Just wanted to add my 2 cents worth. I've used the oven method for almost a decade now without any problems or complaints so far. I use 350 F for one hour (no gradual step up, just fire away) and cool with the oven door closed. I haven't yet had any bottles shatter when I stick to returnables. It's been my experience that if the foil caps are undisturbed, I can let the bottles sit for over a year and they will still be good to go! On an unrelated note, I had to share this story with the group. A friend of mine who I recently introduced to homebrewing, took a lady friend of his out for a beer. Thinking he'd show her what we get exited over about better beers, he ordered a Chimay red. Said lady had a taste and said "mmm, tastes kinda like Budweiser!" Steve G. Smallaxe Brewery Return to table of contents
Date: Sat, 13 Jan 2001 16:08:43 -0000 From: "Bernd Neumann" <homebrewz at hotmail.com> Subject: Looking for Pyramid Snowcap Clone Hi, Anyone have a good Pyramid Snowcap Ale clone receipe? -Bernd Neumann KB2EBE Middleburgh, NY Return to table of contents
Date: Sat, 13 Jan 2001 08:24:27 -0800 From: "Peter Zien" <pz.jdzinc at worldnet.att.net> Subject: Eighth Annual America's Finest City Homebrew Competition Dear HBD Brewers, Please consider participating in the following Homebrew Competition: Eighth Annual America's Finest City Homebrew Competition San Diego, California March 2 & 3, 2001 Entry window February 5-23, 2001 Complete rules and convenient on-line registration for contestants, BJCP judges, and stewards at the Competition website: www.softbrew.com/afchbc/ Contact Peter Zien (pz.jdzinc at worldnet.att.net) for a hard copy of the entry packet. Sponsored by the Quality Ale & Fermentation Fraternity (QUAFF) Return to table of contents
Date: Sat, 13 Jan 2001 11:30:46 -0500 From: Ray Kruse <rkruse at bigfoot.com> Subject: Resources needed I'm looking for an all grain brewer in the Birmingham/Pelham area of Alabama who would be willing to donate some spent grain. Just to satisfy the curious, I make dog biscuits from some of my spent grain and recently sent some to my sister. Her dog loved them and she wants to try her hand at making some, but she doesn't brew, and the crushing/mashing/sparging process is more than she wants to go through. Please contact me directly. Thanks Ray Kruse Glen Burnie, PRMd rkruse at krusecontrols.com Return to table of contents
Date: Sat, 13 Jan 2001 09:45:01 -0700 From: Ken Schwartz <kenbob at elp.rr.com> Subject: Homemade Peristaltic Pump Sean Richens wants a cheap peristaltic pump. Disclaimer: I have not built this nor have I even thought it through but it might get ya started. Get one of those slow speed, high torque motors like the ones used for Mix Mashers. At the end of the shaft, attach a square of plywood. On this square of plywood you have installed four small casters exactly in the center of the four edges. You have also cut off at 45 degrees as much of the corners off as possible, leaving just enough flat edge to mount the casters. (since the corners stick out farther than the edges, we have to clear these back). On the base to which the motor is mounted, you have attached another piece of plywood, with a concave circular cutout. The radius of the cutout is exactly the same as the distance from the shaft center to the outermost point on the caster wheels (all four wheels ideally the same distance). The circular cutout spans maybe 120 degrees of arc, and the cutout is mounted perpendicular to the motor shaft, using two long screws and a spring. The spring is place between the cutout and the base so that you can press on the cutout and it will pop back to position. This will allow adjustment and provide back-pressure against the casters (see below). The center of the cutout arc should coincide as closely as possible to the center of the motor shaft. Use silicone tubing, laid into the circular edge of the cutout. Maybe it will stay by itself, maybe you have to restrain it. Silicone is used because it's heat resistant, inert, and soft & flexible. Check http://www.mcmaster.com for this stuff. How it (supposedly) works: Now as the motor turns the casters meet the tubing, first pressing into it till it's flat, then rolling along the cutout arc, pushing the contents along. Before one caster leaves the cutout arc, the next engages, so the contents are always moving as long as the motor is turning. The spring mounting of the cutout ensures that a tight pressure exists between the cutout and the caster and takes up any error in construction dimensions. Flow rate is determined by motor speed, cutout radius, and tubing diameter. I leave the rest up to y'all. - -- ***** Ken Schwartz El Paso, TX Brewing Web Page: http://home.elp.rr.com/brewbeer E-mail: kenbob at elp.rr.com Return to table of contents
Date: Sat, 13 Jan 2001 08:45:21 -0800 From: Demonick <demonick at zgi.com> Subject: Speaking of Andy Walsh ... From: "Stephen Alexander" <steve-alexander at worldnet.att.net> > ... I owe thanks to Andy Walsh for sending > several of the paper's supporting this view. ... Any of you Aussies seen or heard from Andy Walsh? He was the original Aussie on this group IIRC. I met him once in Oz in Jan 95, and Dave & Chryl Draper (when he was there), Ken & Evi Willing, and Chris Pittock - fine folk all. Welcomed me into their home (Willing's) and city (Sydney) and didn't make too much fun of my accent. Andy, Ken, Chris, (I know where Dave is) if you're lurking out there contact me and let me know y'all are hardy and hale and still full of piss & vinegar & vegemite (http://www.ozchannel.com/vegemite/vegemite.html). Domenick Venezia Venezia & Company, LLC Maker of PrimeTab (206) 782-1152 phone (206) 782-6766 fax orders demonick at zgi dot com http://www.primetab.com Return to table of contents
Date: Sat, 13 Jan 2001 12:48:32 -0500 From: Paul Shick <shick at jcu.edu> Subject: RE: Recirculation problems with RIMS Hello all, Now that my brewery is finally up and running at the new house, I feel I've earned the right to participate in the HBD again. Five-plus months away seems like a long time... Nathan Kanous writes about his reasons for wanting to recirculate during his mash (all good ones!) and his problems with compacting the grain bed while doing so. He asks if it matters if he recirculates through the compacted bed as best he can, then stop for a mashout, stir the bed to uncompact it, then sparge as usual. Nathan, I'm pretty sure that stirring the bed will undo any clarification you achieved during your recirculation, kicking loose lots of particulates as you loosen up the bed. Unless you recirculate enough to let the grain bed filter these out, your problems with wort clarification aren't likely to go away. My suggestion would be to try to go with the low pump flow rate that you mentioned. Unless you're running a heating device (burner or electric) that risks scorching the wort, I can't see any drawbacks to keeping the wort recirculating slowly. Even with a natural gas jet burner going (on low,) my system seems to work well at about one half to one gallon per minute, with no signs of scorching. These sorts of rates should be low enough to avoid compacting all but the most finicky mashes (those with large quantities of oatmeal, for example.) A slow recirc rate should still give you the kind of clarity you're looking for, and has the added benefit of being less susceptible to HSA problems. (I can't believe I raised that issue in my first post back!) Good luck sorting out your pump problems, Nathan. Can you let us know how things work out? Paul Shick Basement brewing (at last) in Cleveland Heights, OH Return to table of contents
Date: Sat, 13 Jan 2001 12:50:29 -0500 From: "Eric Ahrendt" <rock67 at peoplepc.com> Subject: Phil's bottom and polypropolyene In HBD #3527 Dan comments: "Phil's' Phalse Bottom is made from polypropylene and I can tell you that after almost ten years of making them that they do not deform ( I deform in the the process of making them) until the temperature almost reaches 300 F. This is very unlikely to be reached in a brew kettle even at the contact point and even if steam is traped under the bottom. Steam of this temperature would require more than 50 psi to hold it back. We have yet to hear our first complaint about a bottom deforming due to boiling." First off, this is certainly not meant to be a criticism of Dan's products - certainly he knows more about them than anyone and I'm sure that his claim of no complaints is true. Actually, I've never seen a Phil's Phalsie. However, polypropylene is a borderline material choice for this application. Depending on the grade and filler, the heat deflection temperature of polypro isn't too much higher than boiling. HDT depends on stress, and I guess we can say that there is little or no stress on the false bottom during the boil. At any rate, the boiling temp of the sugary wort solution is pushing the limit of polypropylene. Once again, not a criticism. Obviously many hours or real life testing have proven the material properties to be adequate in this application. I simply wanted to point out the limitations of polypro as I am all too painfully aware of them. I can't say any more since my customer is certainly listening. I'm sure that Dan uses the material for the same reasons my employer does - it's cost and processability make it very attractive. Eric Ahrendt Fremont, OH Return to table of contents
Date: Sat, 13 Jan 2001 12:00:23 -0600 From: "Sean Richens" <srichens at sprint.ca> Subject: Re: Peristaltic pump source Thank you to Fred, Kevin and Eddy for their input. Cole-Parmer can start out pretty cheap, but even one extra bell or whistle (and who can refuse?!) gets the price screaming up. Bill at Moving Brews is proposing a nice little diaphragm pump, which should be sanitizable enough. It also has adequate "gadget factor" for a closet gear head. Sean Return to table of contents
Date: Sat, 13 Jan 2001 15:10:19 EST From: Doniese at aol.com Subject: fermentation cabinet I have a question for Forrest (FridgeGuy), or anyone else with experience in such things. Living where I do (in the Pacific Northwest), and fermenting where I do (my garage), maintaining the proper fermentation temperature for my ales is, for most of the year, a matter of keeping the temperature warm enough. I solved this by building a simple insulated fermentation cabinet, and heating this with a very small forced air heater (through a duct). It has worked well for me so far. Soon I will be moving to a larger (10 gal) SS conical. I will be building a larger cabinet, constructed and insulated using the same design as Forrest used for his cold room (see HBD around July if you missed it - very informative). I'll be using the same method for heating, but would like to add the option of cooling for summer months and the occasional lager. My idea is to make it possible to attach my small (maybe 3.5 cubic ft) dorm fridge to the cabinet (details for a good seal are yet to be worked out). The fridge itself is relatively new and in good condition. The cabinet inside dimensions will be approximately 24 x 24 x 50, or nearly 17 cu. ft. For temperature control, I'll use my Brewer's Edge Controller II, with the temp. probe in a thermowell in the side of the fermentor. My questions are these: assuming (eek) a well sealed and insulated cabinet, what sort of temperatures could this set-up maintain? Can it handle maintaining primary fermentation temperatures of 10 gal of a lager beer with an ambient temp outside the cabinet of, say 75 degreesF? (Hey, it happens occasionally here). What sort of problems might I expect? Any alternate suggestions? I'd appreciate any ideas or suggestions anyone can give. Oh, and for the record, I hope that all on the HBD realize our luck in having a guy like Forrest around, who not only is very knowledgeable in a subject that is important to us, but has freely shared his knowledge. It's folks like this that make the HBD invaluable to hombrewers of all levels!! Thanks Forrest! Private Emails are welcome, or reply to the digest if you like. Craig Jensen Wa. State Return to table of contents
Date: Sun, 14 Jan 2001 08:58:56 +1100 From: "Helen Pay" <hpay at optusnet.com.au> Subject: Bad Boy On Holidays Homebrewing is a safe hobby. At least when I am at home testing a new brew, giving it a nudge or what ever you like to use to describe perhaps having a few more than you should, I can't get into too much trouble. Rarely do I wonder far from the garage where my fridges are kept. Well I don't need to, the best beer in the world (your own) lives there. But on holidays, well even the best intentioned homebrewer is cast adrift. I am not the most popular boy in the house at the moment. Having gone out on Friday night to the Avalon Bowling Club for a few quick beers I failed to return at the appointed time. In fact I failed to return at all. My intensions were pure but unknown to me I was to be the victim of what can only be described as a premeditated and most vicious attack carried out in series by an endless stream of old friends. I was forced to drink just one more Tooheys Old and one more Tooheys Old and one more Tooheys Old and.........so it went on. Hungry and miserable, with all communications with mother shut down (she turned off the phone) I stumbled the streets way out on the wrong side of midnight hoping for a taxi to get me home. What miserable bit of the night that was left I spent on the lounge which has put my neck out horribly. I have been a bad boy and I am suffering. Jill's silence is causing me more bother than my neck. But Phoebe still loves me. Thank God for little daughters. I will be glad to get home to the safety of my homebrew!! Cheers Phil Return to table of contents
Date: Sat, 13 Jan 2001 13:50:00 -0600 From: Jay Pfaffman <pfaffman at relaxpc.com> Subject: Re: 6% alcohol limit Though some might couch it differently, my understanding is that the rationale for limiting the strength of beer was to keep poor people from being able to be able to get drunk inexpensively. So the reason that you can't buy Chimay is that someone didn't like people drinking inexpensive malt liquors. In Tennessee the %5 or %6 limit is still in place, but wine/liquor stores now carry strong beers. Here beer can be sold in supermarkets or beer stores, but wine and liquor must be sold in stores which sell only wine and liquor. It may be easier to have strong beers sold as wine than to have the definition of beer changed. On Wed, 10 Jan 2001 08:37:55 -0800, larry matthews <lmatt at ipass.net> said: > A small cadre of NC homebrewers are planning to lobby our state General > Assembly to alter the current definition of beer as being below 6% by > volume. Most other states have no limit or a substantially higher limit in > their definition. Trying to do some research on where the 6% limit came > from. I know it was developed after the state Prohibition was ended in NC > in 1935 (yes, after the National repeal). However, nowhere have I found a > rationale for the 6%. Some states have an even lower 3.2% level. Can anyone > point me to some website or a written source that will discuss this > rationale. I believe this will give me some insight into how to approach > our appeal to the General Assembly. > Larry Matthews > Carboy/Trub Member > Raleigh, NC 27606 > lmatt at ipass.net - -- Jay Pfaffman pfaffman at relaxpc.com +1-615-343-1720 (office) +1-615-460-9299 (home) http://relax.ltc.vanderbilt.edu/~pfaffman/ Return to table of contents
Date: Sat, 13 Jan 2001 20:00:11 -0500 From: Jim Adwell <jimala2 at ptd.net> Subject: HSA is good for beer? At the risk of opening up the debate about HSA again ( which is NOT my intention), I came across an interesting piece of information in a turn-of-the-century brewing book, and share it with you now. My motive in this is to find out if anyone else interested in old brewing practices has seen anything similar in other books (Jeff Renner, for example), or uses this technique in their own brewing. I don't have any idealogical horse to flog either for or against it. >From The Cambridge University Press: The Cambridge Manuals of Science and Literature - Brewing published 1912 by A. Chaston Chapman President of the Institute of Brewing Fellow of the Institute of Chemistry of Great Britain and Ireland Fellow of the Chemical Society >From Chapter V - Cooling, pages 66-67: "In the majority of breweries at the present day, both a cooler and a refrigerator are employed, but sometimes the cooler is done away with entirely or is replaced by a deep receiving vessel, a system which has much to recommend it, as I shall show later. It should be said, however, that the cooling of the wort is not quite the only function of the cooler. Certain of the constituents of the wort have the property of absorbing oxygen from the air at tolerably high temperatures, and this 'hot aeration' as it is called, to distinguish it from the cold aeration or absorbtion of oxygen by the cold wort while passing over the refrigerator, is very generally regarded as beneficial. It is true that some authorities have questioned its importance, but I think there is a general consensus of opinion that these more or less obscure oxidation changes are desirable and that they do exert an appreciable effect on the brightening capacity of the finished beer. It is fortunate, however, that these changes occur most actively at elevated temperatures, - about 180F., and it is very doubtful whether much if any advantage in this direction is gained by allowing the temperature of the wort on the cooler to fall below, - say 160F. A further function of the cooler is to permit of the deposition of the coagulated protein matters from the cooling wort and to leave the bulk of these behind when the wort is run down over the refrigerator. This insoluble deposit is technically known as the 'cooler sludge.' There can be no doubt that if the wort on the cooler could be reduced to a comparatively low temperature under conditions rendering bacterial infection impossible, the shallow vessel of large area has much in its favor. In practice, however, this is very difficult, and many brewers have found that they can secure the main benefits of a cooler without its serious drawbacks by substituting for it a deeper vessel of much smaller area. By spraying the wort pumped from the hop-back into such a vessel sufficient 'hot aeration' is secured, and if it is not possible to keep the protein sludge back as completely as with a cooler, the advantages on the score of diminished infection are so great as to render this consideration of little importance. Above 150F the wort is practically sterile, and the brewer should endeavour by every means in his power to ensure that the temperature of the wort when it reachs the refrigerator shall not be appreciably lower." Notes: "Cooler" refers to a cool-ship, i.e. a shallow pan of large area open to the outside air, and "refrigerator" refers to artifical cooling, whether by cold water or ammonia. I have left this as found, with no paragraph breaks; the book tends to have paragraphs 10 or more pages long. Overall, this small book is quite interesting, providing a concise overview of brewing in England circa 1912, and a few surprises, too. :) Cheers, Jim Jim's Brewery Pages: http://home.ptd.net/~jimala/brewery/ Return to table of contents
Date: Sun, 14 Jan 2001 05:13:31 -0800 From: Yahoo! Finance <refertofriend at reply.yahoo.com> Subject: Yahoo! Finance Story - Yahoo - StarLink contamination found in beer ingredient-FDA Darrell Leavitt (leavitdg at plattsburgh.edu) has sent you a news article - ------------------------------------------------------------ Personal message: Yahoo - StarLink contamination found in beer ingredient-FDA http://biz.yahoo.com/rf/010112/n12640670.html ============================================================ Yahoo! Finance http://finance.yahoo.com/ Return to table of contents
Date: Sun, 14 Jan 2001 11:08:50 -0500 From: "Stephen Alexander" <steve-alexander at worldnet.att.net> Subject: re: dropping (aeration really) Der Pivo sez .. << The upshot of this was, that overoxygenating in the beginning (as is often reccommended here) actually leads to premature beer staling, as while eager to absorbe oxygen, the yeast are certainly not putting EVERY molecule into sterol synthesis (this should be inherently obvious, but I shall leave the enzyme kinetecists to scratch their heads over it), and will oxidise things that you may not want getting oxidised. Perhaps the most reasonable approach would be to give them less O2 in the beginning, and then more when the cell wall building process is in greatest upswing. If you have a microscope and a Buerker chamber, this is the point where you have the greatest proportion of budding cells... at Suntory this was about 24 hours after the pitch (not 14). >> The statement suggestion, that "overoxygenating in the beginning [...] ) actually leads to premature beer staling", where overoxygenating means introducing more oxygen than the yeast can use, should cause no headscratching unless you pick up head lice from the author. Actually oxygenating beyond the amount yeast can use is always a bad thing. BUT note that the fermentation process creates a lot of stuff with great staling potential. If you want to compare the flavor damage of excess initial vs later (beer) aeration, try the trivial experiment. Aerate a wort , and a beer sample well.. If you can't tell which one has more flavor damage with one sniff your nose needs realignment. Aerating late carries greater flavor damage potential. The second suggestion, that the O2 is needed during cell budding isn't supported by evidence. Sterol is needed during the cell-membrane building. Oxygen is need to form sterols when the precursor conditions arise, that is squalene and glycogen are present. I've two studies but, one from a Czech book on brewing yeast and a more detailed study in JIB that point to a (dare I say it with Dave Burley absent ?) a stochiometric relationship between the yeast use of glycogen and the production of sterols from squalene. No glycogen = no(very little) sterol, even if O2 is present. If yeast are allowed to complete a fermentation & flocculate in an anaerobic (beer) environment they will normally build up massive stores of the storage carbohydrates, glycogen and trehalose, and also squalene the precursor to sterols. When they are subsequently pitched into wort they initially ignore the wort sugars(!!) and use their internal storage carbohydrates and produce sterols from the squalene, assuming O2 is available. In one study yeast sterol levels went from 0.1% to 1% in the first two hours and the levels of glycogen dropped dramatically at the same time(75%-90%). Also the fraction of UnsaturatedFattyAcids (which also require O2) rose from 10% to 50% of all lipids during that initial period. Yeast don't rebuild their glycogen reserves much till after catabolite repression ceases. After that the yeast modestly gain in glycogen, but there is no huge accumulation till late fermentation when growth ceases. In other words, glycogen, which may be the potential to produce sterol, is highly available in healthy recently flocced yeast only. If you don't aerate at their early 'kick-off' phase of fermentation, the yeast will use the glycogen anyway (gotta eat) and you've lost the best opportunity to create sterol. So if you are pitching dormant yeast, initial aeration seems an excellent idea. If you are pitching a starter at full krausen - that's a different story and you should probably wait till after catabolite repression ceases. This happens about the same time or a bit after the wort is CO2 saturated and the bubbler starts working for normal gravity all-malt wort. Maybe this is the 14hour figure of Dr.Cone. If you are adding sugar this point will occur later. Oh yes - by all means experiment - nothing is cast in stone or proven beyond doubt. Even HBers can get an indication of yeast glycogen reserves with an iodine test. Fix describes this in one of his books as a substitute for a viability test. Think conversion iodine test, but you are looking for/hoping for 'yeast starch' (glycogen). There has also been some work growing yeast on 'oxidative' carbon sources, ethanol and mannitol, sorbitol (the yeast respire/use O2) to very good effect re sterols and O2 consumption. -Steve Return to table of contents
Date: Sun, 14 Jan 2001 17:30:10 -0700 From: "William Graham" <geeks at att.net> Subject: Dishwashing scum Greetings - I was wondering if anyone could tell me how to get rid of "dishwashing scum" from my bottles. This is the scum ( not actually visible ) that is deposited by the soap and the sheeting additive in the dishwasher that severely limits head-retention. I was thinking that a soak in tsp would work, but I recall a previous post mentioning that tsp scum should be removed with vinegar. So how can I get my dishwashing-scummed, tsp-scummed bottles squeaky clean? Thanks, Bill in Golden, CO where the smell of boiling wort is in the air. Return to table of contents
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