HOMEBREW Digest #2711 Tue 12 May 1998

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		Digest Janitor: janitor@hbd.org
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  Re: ruined malt/aldehydes & phenolics/phenolics&lag phase ("Steve Alexander")
  yeast energizer/nutrient ("Chris Storey")
  Hop Help Needed ("Frederick L. Pauly")
  Evaporation Rate? (Tim.Watkins)
  Rodenbach Grand Cru update (Ted_Manahan)
  An Apology to Scott (Troy Hager)
  Albuquerque/Santa Fe, NM & Denver/Boulde (GIBBONJJ)
  "thermal loading", 1/2bbl fermenter ("Eric R. Tepe")
  Dangerous Duvel, or Further Belgian Experiences... (Charley Burns)
  Instruments, pH Measurements (Jim Liddil)
  RE: Kegging in an Apartment (erikvan)
  DMS and kettle lids (Al Korzonas)
  George Bashing (Al Korzonas)
  Foam Once Proteins (Al Korzonas)
  trans-2-nonenal (Al Korzonas)
  re:redox ("Dr. Pivo")
  pH measurements part 2 (Jim Liddil)
  Suggestion ("Jim & Shelly Wagner")
  Thermal Loading & Snide Comments (Jim Bentson)
  trans-2-nonenal ("Mort O'Sullivan")
  Back to Boiling Basics (David lamotte)

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---------------------------------------------------------------------- Date: Mon, 11 May 1998 00:11:57 -0400 From: "Steve Alexander" <steve-alexander at worldnet.att.net> Subject: Re: ruined malt/aldehydes & phenolics/phenolics&lag phase George De Piro writes ... Subject: Is my malt ruined? > I'm just finishing up a 1.5 week home malting project. I finished mine about 2 weeks ago. Tho' only pale malt and light crystal were on the menu. Sorry to hear your Munich didn't turn out. I brewed a Preprohibition style American lager from some of this 6-row homemade malt and ~22% maize flakes (a la G.Fix and Jeff Renner). Which is coolly fermenting with Wy2035 at the moment. The mash got a positive iodine test after 20' at 60C + 15' at 70C. Apparently I got good diastatic power from my malt. One tidbit for the home maltster is that a crockpot set on low makes a rather nice crystal malt 'stewing' oven. Conventional ovens are the pits for good temp control in the range needed. The aroma of fresh crystal is also astonishing - quite a bit stronger than I had imagined. There is an offhand remark in M&BS noting that specialty malt loses it's flavor over time - so should be obtained fresh - I just never had such a fresh example to work with before. >In the old days, crystal malt was made by steeping finished pale malt >until a moisture content of ~45% was reached. You should change the >steep water quite often to avoid souring of the malt if you do it this >way (lest you make acid malt). Once the malt is appropriately wet, you >cover it and heat it to as close to 145-160F as you can to saccharify >it (just like mashing). After a couple of hours it will be noticeably >sweet and somewhat darker (keep an eye on it if you are trying to make >light crystal). You can then uncover it, let it dry, and raise the >temp anywhere from 170F to 350F to make the color crystal you want and >dry the malt. Easy! I guess I'll be trying this with some 2-row pale someday soon. Has anyone else ? Comments ? - -- Dave Burley also writes ... >Also, acetaldehyde is a major component in sherry along with lots of >other aldehydes.a Acetaldehyde is largely responsible for the >disappearance of the anthocyanins from red wines used to make sherry >as the acetaldehyde formed by the air oxidation of alcohol. >Acetaldehyde reacts with the anthocyanins and the complex >precipitates. There are at least two mechanisms proposed for the reduction of anthocyanins from wine. The most clearly demonstrated mechanism is a polymerization/oxidation reaction with bi-proanthocyanidin. The proposed acetaldehyde mechanism joins polymeric proanthocyanidins, but can either use free acetaldehyde, or acetaldehyde formed in a coupled reaction involving oxidized o-biphenols, rather than "air oxidation". See 'Plant Phenolics', E.Haslam, Cambridge Press, 1989 for the full story. - -- Another recent note I came across claims a relationship between the lag phase of fermentation and amounts of coumaric and ferulic acids added. The coumaric in normal wort could never reach the levels used in this test fermentation, and the amount of ferulic required would be a stretch too - tho' perhaps only 2X or 3X that of a weizen bier wort. The abstract didn't indicate whether the results of the two were additive, nor whether other phenolics were involved. It does lead to some interesting speculation on the true cause of lag phase tho'. Steve Alexander Return to table of contents
Date: Mon, 11 May 1998 08:23:41 -0400 From: "Chris Storey" <cstorey at nexicom.net> Subject: yeast energizer/nutrient Hello Brewers! I need to use some yeast energizer or yeast nutrient for my next brew. I was wondering what the difference is between them. Also, how and when should they be used. During the boil? After the boil? etc. TIA, Chris Storey Return to table of contents
Date: Mon, 11 May 1998 08:38:33 -0400 From: "Frederick L. Pauly" <flp2m at avery.med.virginia.edu> Subject: Hop Help Needed I've been trying to find a supplier that sells really fresh whole hops and have been dissappointed. I bought an 8 oz. bag of cascade, well packaged from a well known supplier and yet when I split a 10 gallon batch and dry hopped one half in the secondary with 1/2 oz for 2 weeks there was zero hop aroma and only a touch of hop character compared to the non-dry hopped half. Granted, it could be my technique. So I am asking for insight and suggestions for your favorite source of hops. Thanks Rick Pauly Charlottesville,VA Return to table of contents
Date: Mon, 11 May 98 9:45:23 EDT From: Tim.Watkins at analog.com Subject: Evaporation Rate? Hey all, The recent thread on evaporation rate has piqued my interest. It seems that the "big guys" (read: commercial breweries) recommend a 10% to 15% evaporation rate. It also seems that this is just about impossible in the home setup because of a variety of factors. One thing that hasn't been mentioned is the form of heat everyone is using. IIRC, the big guys use steam injection to boil their wort. Could it be that in the course of the steam giving up it's heat to the wort, that it will condense back into liquid, and thus replace *some* of the water that is evaporating? Could this be one reason why they seem to get less evaporation than we do at home? Is there anyone out there using steam injection at home who can comment on the above? Just a thought, Tim in Lowell, MA Return to table of contents
Date: Mon, 11 May 1998 07:42:18 -0700 From: Ted_Manahan <tedm at hpcvn2ax.cv.hp.com> Subject: Rodenbach Grand Cru update A few weeks ago I posted an inquiry as to what category to use for a Rodenbach Grand Cru clone. I recently entered the beer in the Oregon Homebrew Festival. The AHA guidelines were used, and they don't have a Belgian Red category. I used Specialty and Experimental. I was fortunate to have Fred Eckhardt as lead judge in that category. The "Homebrew Grand Cru" was awarded first place in its category. It was also runner up for best of show! One of the judges told me that during the judging there was a discussion of whether the beer was entered in the wrong category. The consensus was: "what else are you going to do with it?" Thanks for your help. Ted Manahan tedm at cv.hp.com 541/715-2856 Return to table of contents
Date: Mon, 11 May 1998 19:12:05 -0700 From: Troy Hager <thager at bsd.k12.ca.us> Subject: An Apology to Scott HBDers, Recently I posted a private email message from Scott Murman and because of this he has recieve a lot of flack. In no way did I mean to put Scott or his opinions (which I respect) in the firing line - but that is what happened and I would like to make my apology known in public as I have in private. -Troy Return to table of contents
Date: 11 May 1998 12:47:00 -0500 From: GIBBONJJ at apci.com Subject: Albuquerque/Santa Fe, NM & Denver/Boulde I'll be visiting Albuquerque/Santa Fe, NM and Denver/Boulder, CO during June. I would welcome suggestions from HBDers on good "not to miss" brewpubs to visit while there. Private E-mail is fine. Much thanks in advance, John Gibbons Allentown, PA Return to table of contents
Date: Mon, 11 May 1998 13:28:41 -0400 From: "Eric R. Tepe" <erictepe at fuse.net> Subject: "thermal loading", 1/2bbl fermenter Just a quick post, 1) on the burner debate I use a Cajun Cooker and it appears to burn well with little soot. I have brewed 3 batches (2-five gallon and 1-ten gallon) and used the tank for my gas grill. I don't think thats too bad. I bought it at Sam's for about $40. 2)Can anyone tell me what "thermal loading" is? Eric R. Tepe Return to table of contents
Date: Mon, 11 May 98 11:22 PDT From: cburns at egusd.k12.ca.us (Charley Burns) Subject: Dangerous Duvel, or Further Belgian Experiences... So now I know why they have those wire baskets around the corks on Belgian Beers... My buddies Victor and Jeff came over Saturday to get some help building a mashtun - ready to make the jump into all-grain brewing and wanted some guidance. Their bribe was a bottle of Grand Reserve Chimay and a bottle of Duvel. The Chimay was delicious with our barbecued sesame-honey-ginger chicken (marinated for 2 weeks - mmmmmmm). After hacking away at some copper pipe, we finally got to sit down with the Duvel. I had barely loosened the wire basket when FFFFOOOOOPPPPP!!! The cork nearly put my eye out as it whizzed past my face something just short of lightspeed. Even left a dent in the ceiling. So watch out! Open those things with great care or you may end up like that alternative music group "One Eye Blind....". Charley (leaning to one side as I open corked bottles) in N. Cal Return to table of contents
Date: Mon, 11 May 1998 11:50:54 +0000 From: Jim Liddil <jliddil at azcc.arizona.edu> Subject: Instruments, pH Measurements On the thread regarding Clinintest, Hydrometers, refractometers etc. I have a few opinions. I am surprised Dave Burley or anyone else never discusses the fact that regardless of the method one still should calibrate or standardize the test or instrument. I use the Clinitest and I like it particularly for testing things like my BigBrew barley wine. I don't have to waste 200 ml using the hydrometer. And I'm proud to say that after 7 days it is at <1/2% sugar as measured by the Clinitest. So it's not stuck. :-). BUT the Clinitest comes with no standards (i.e sugar solutions of known %). This is a one point test with no standard curve. I certainly would never run an analysis here in the lab with out doing an appropriate standard curve. Granted it has approval for what it is meant for (diabetics), but the package indicates that you should keep it in a dry cool place and not use it beyond the expiration date. If I get totally obsessed I'll dig up the original papers and make all the reagents up separately and prepare known sugar standards. The same applies to hydrometers and refractometers. They need to be calibrated. I know a number of people who have had problems in brewing only to find their hydrometer was out of wack. And if I recall BT never did publish a correction to the hydrometer calibration "procedure" that was in the magazine a few months ago. And anyone who has had the joys of P chem lab would certainly appreciate the need to calibrate a refractometer properly. And things do get dropped and a refractometer is not cheap. Nalge does make a polycarbonate hydrometer and I've dropped it three times and the calibration using water and know sugar solutions is fine. Do brewers use pH meters without calibrating them first? The new Barleywine book. Basic not much historical detail. An easy read. I guess if I was a newbie I would be more impressed. But to me it reads like the authors were going thorugh the motions. I like the Altbier book better. And the book Andy Walsh mentioned (beer:tap into the art and science) is certainly a good deal for the price. I did my own version of the pH vs Temp malt measurement. Quick and dirty and I'm sure many will find faults in the methodology but here is the data for all to review. University Water: Alkalinity145 Calcium 52 Chloride 14.5 Hardness 159 Magnesium 6.8 pH 8 Sodium 38.8 Sulfate 66 TDS 319 I also used water from a Barnstead Nanopure water system. The water read 17.7 megaohms resistivity. This is a system that produces pyrogen ultrapure water Type 1. The malt was the Czech Pils malt from St. Pat's of Texas. Malt analysis is on their webpage (www.stpats.com) pH Meter: Corning model 340 Resolution: 0.01 unit pH, 1 mV Accuracy : 0.01 pH, 1 mV Note: I know AJ mentions having 0.1 mV resolution but those units retail at more than $500 in the VWR catalog. Electrode: Orion/ROSS Sure-Flow Semi-micro Combination electrode Temp range up to 100 C. The electrode is 7 months old. The pH Buffers were pH 4 and 7 and come from VWR scientific. They are their house brand. The thermometer was a VWR digital traceable instrument with 0.1 C resolution. Meter was calibrated and pH and mV measurements taken: pH=4 189 mV pH=7 17 mV I prepared a pound of malt and then weighed out 13 grams samples into beakers. In the process I tried to keep the mix as uniform as possible though this is hard to do with ground malt. (an experimental short coming) I added 100 ml of either tap or ultrapure water to each beaker. The water was drawn from the tap or filtration system into polypropylene beakers and allowed to equilibrate for 1 hour prior to start of experiment. Samples were them mixed and temperature and pH measured. Temp 76 F (all samples) Tap water Mash Sample # pH/mV 1 6.58/43 2 6.62/36 Samples were placed in water bath at 145 F for 30 minutes with occasional stirring. Sample reach 145 F after approximately 20 minutes. The water bath was setup at the pH meter so that temp was constant (+/- 1 F). pH/mV at 145 F pH/mV 1 5.85/84 2 5.84/84 Samples cooled on ice to 76 F pH/mV 1 6.15/65 2 6.16/65 Type 1 water mashes 76 F pH/mV 1 5.70/91 2 5.75/90 145 F 1 5.47/104 2 5.45/105 76 F 1 5.84/84 2 5.78/87 I left 13 grams of malt at 76 F during the whole test (~60 minutes) and after this time the pH/mV were 6.26/59 I checked the pH meter after the experiment and the buffer reading were identical to those at the start This experiment represents an N=1. Return to table of contents
Date: Mon, 11 May 1998 14:16:35 -0500 (CDT) From: erikvan at ix.netcom.com Subject: RE: Kegging in an Apartment In HBD #2709 Brian Paszkiet asked about kegging in an apartment: I used to be in a similar situation, until I got married. At the time, I tried laying kegs down, but the first time I did this, I woke up the next morning to find a damn good steam all over the kitchen floor! If you do lay your kegs down, make sure your keg gaskets are good, and sealed tight. But why not try a small chest freezer? You can get a 7cf for $250, and it occupies a 2x3 foot space. You can hold about 5 kegs, or a couple carboys. When you get more money, you can add chrome columns with faucets later. Works great! Good luck with your solution! Erik Vanthilt erikvan at ix.netcom.com The Virtual Brewery Http://www.netcom.com/~erikvan/brewery.html Return to table of contents
Date: Mon, 11 May 1998 14:24:23 -0500 (CDT) From: Al Korzonas <korz at xnet.com> Subject: DMS and kettle lids Jeremy writes: >On a related note: I think that all this concern over >covering the boil is BS. DMS is incredibly volatile. Unless you're >using a pressure cooker I don't see how you could keep it in if >you wanted to. I used to just crack the lid on my boils when I >used an electric stove and I didn't have excess DMS (IMO). I >recently did the experiment suggested here a few years ago and >collected the condensate from my lid during the boil and tasted it. >Water. I feel that Jeremy's experience should be considered as one datapoint. I have done the same and the condensate smelled strongly of cooked corn. Check the archives from about 93 or 94 and I believe it was Jim Busch who initially did this experiment and he too got a lot of cooked corn (DMS) aroma in the condensate. Might I suggest that perhaps the malt you used was very low in SMM (the precursor of DMS) or perhaps the room was filled with the smell of DMS and therefore the sample didn't smell much different than the room air... I really got different results than you did... I do agree however, that even a small opening in the lid should be good enough to prevent excessive DMS in the finished beer. Back when I used to brew on an electric stove, I had to cover the kettle about 90% and as long as I cooled the wort quickly, I didn't have any noticeable DMS in my ales. I think that as long as you cool the wort quickly and don't cover the kettle 100% you should be okay. Al. Al Korzonas, Palos Hills, IL korz at xnet.com http://www.brewinfo.com/brewinfo/ Return to table of contents
Date: Mon, 11 May 1998 14:48:26 -0500 (CDT) From: Al Korzonas <korz at xnet.com> Subject: George Bashing Dave writes: >My suggestion is let George explain it, if he can. Like >Scott Murman says, if past behavior is any example - I >doubt if he will provide any data to back this up, nor comment. If you knew George Fix like I know George Fix, you would clearly see how absurd your statement is. Dr. Fix has been more forthcoming with information that impacts us homebrewers than anyone in brewing. Day job aside, he can probably make a good living simply as a brewing consultant. The fact that he has time to answer questions here amazes me and when he *has* the time to post something here, it has *never* failed to be informative and immediately useful in my brewing. There's a nice way to ask for more information and a rude way. Your ways were rude... it's called "flamebait," incidentally. There are a number of things in his books that have either confused me or I wished that I had more information... I suggest you do as I did... wait until you meet him at a conference and then ask him personally. Then buy him a beer, because without a doubt you learned a lot more than just about what you had asked. I feel that all of you that have bashed George here in HBD owe him an apology! Al. Return to table of contents
Date: Mon, 11 May 1998 15:33:44 -0500 (CDT) From: Al Korzonas <korz at xnet.com> Subject: Foam Once Proteins HBD Old-Timers will recall the discussion of Foam Once Proteins (FOP) we had a couple of years ago. It seems to have been introduced again by AJ: >do it right, but nobody that I know does it right except Rhett Rhebold. >He mentioned to me once that he had learned at Siebel that protein that >participates in forming a froth during aeration is lost as a source of >foam in the final product. As a consequence of this when he oxygenates >he sets the flow so low that foam does not form at the surface. After our long (relatively unfruitful) discussions on HBD, I proceeded to test one aspect of foaming and head retention. I compared the protein content and head retention of two batches (an American Pale Ale and an IPA) that had been split into blowoff and non-blowoff fermenters (two worts -- four batches after splitting). Details of this experiment can be found in my Brewing Techniques article "When Fermentation Rears It's Dirty Head" published a few years ago. The bottom line (among other results) was that there was very little difference in protein as measured by Siebel and no difference in head retention as judged by a dozen BJCP judges. Now, as in the article, I suggest that this was not conclusive and that the level of protein loss may have made a difference in the head retention if the total level of protein was lower (i.e. if it was a style which inherently has lower protein levels). However, I assure you there was an incredible amount of blowoff, far more than you would expect from losses during aeration, and that my gut feeling is that head retention need not be a concern regarding aeration/oxygenation or blowoff. *Bitterness*, on the other hand, was significantly reduced in the blowoff batches and I would not be surprised if it was not also affected if a significant amount of wort was lost to foam duyring aeration/oxygenation. Al. Al Korzonas, Palos Hills, IL korz at xnet.com http://www.brewinfo.com/brewinfo/ Return to table of contents
Date: Mon, 11 May 1998 16:40:25 -0500 (CDT) From: Al Korzonas <korz at xnet.com> Subject: trans-2-nonenal Dave asks about trans-2-nonenal and how a 9-carbon compound got into beer... As it turns out, I happen to have brought my "arsenal" to work today for a completely different reason (my arsenal is MBS, DeClerck, Brewing Science edited by Pollock, Fixs' PoBS and AoBT, and the MBAA text). I needed to look no further than PoBS to find (on page 70) that: 1. I had misspelled it with "ol" at the end and indeed "al" is representative of aldehydes (Jeremy pointed this out to me via email and also noted that acetaldehyde is more accurately called ethanal), 2. it is formed via redox (thanks AJ) reactions from one of the higher alcohols, 3. 2-nonenal is O # H3C-(CH2)5CH=CHCH (where the "#" is actually a double bond), 4. it has a flavour threshold of 0.00011 mg/l, which Fix says is more than 100,000 times lower than that of acetaldehyde, and 5. it does indeed have a "papery-cardboard" aroma, according to Fix. So, I believe all my silly speculation about varying affinity for being oxidised could have been avoided if I had a second copy of PoBS here at work. Al. Al Korzonas, Palos Hills, IL korz at xnet.com http://www.brewinfo.com/brewinfo/ Return to table of contents
Date: Tue, 12 May 1998 00:00:23 +0000 From: "Dr. Pivo" <irv at wireworks.se> Subject: re:redox There has been some interesting, and highly speculative comments about "redox", and it's effect on beer. While I think that oxidation/reduction is essential to understanding some of the "finer " points of what happens to beer (in fact what happens to ANYTHING), most of these comments have centered around some very isolated events, and have dallied about, perhaps focusing attention on a few reactions, and missing the "big picture". In the midst of this A.J. De Lange has sent down, what seems like a clear light from heaven, in the clarity of what he his saying. I think, however that his comments are at the same time too complex for the average brewer, and over simplified in describing what is going on during the process. "too complex"? To the non- native Science speaker, the "Nernst" equation, might just as well be the "Nerd" equation. Trying to remember what is on which half of the equation, and who's on top or bottom of the "denominator", is not an easy task for those who don't do it routinely. As a continuing attempt to make chemistry understandable, and myself rediculous, I will present the following explanation of "oxidation- reduction, and potentials thereof".... "There are two guys standing outside in the cold, and one of them has a hot potatoe in his hands". That's it. Easy, huh? Now if the temperature difference between these two guys hands, is the "potenential" for the potatoe being passed (the potatoe is the electron, in case you haven't guessed that), you know that if the one pair of hands is colder than the other, sooner or later that potatoe is going to get passed.... the colder the hands, the more likely sooner. If the presumed recipients hands are actually warmer (here there is "negative" potential), that potatoe is going to be chucked right back at the sender.... no oxidation, because of their relative postion on the "redox" (hand temperature?) scale. Now the great thing about chemistry, is that these "guys" never get cranky, and refuse to play the potatoe game. In fact to draw the biological analogy farther, you can call these in real honest-to-god chemistry talk, two "species", and they always retain their respective "potatoe -passing/acceptance level" with respect to each other. Nice of them, don't you think? I hammer this simple analogy belatedly, because I continue to read comments like "X might have a greater affinity for oxygen than Y", even after Delange's nice description. Oxygen has nothing to do with it. While it is a great potatoe capturer in itself (REALLY cold hands!), the oxidation that is being described is just potatoe (electron) passing. Oxygen just happened to get tagged with the name of the offence. This is like calling all acts of malfiesance a "Hitler". If you say "Boy, that guy really did a Hitler", it doesn't mean that the guy with the Charlie Chaplin moustache, the boy scout shirt, and the spit polished boots was actually there. ...we just borrowed his name. Oxygen is a SYMBOL of potatoe snatching. This of course gets more confusing in brewing, since sometimes it IS actually oxygen doing the oxidizing. "over simplified"? There always seems to be certain reactions that are repeated again and again, in order to try and elevate the "art" of brewing to a science. One of them is the oxidation of ethanol to acetaldehyde (or indeed all alcohols to aldehydes). Another drum that is favoured in beating, is the influence of HSA on the finished product. In this model, the melanoidins are seen as the "universal redox middlemen". Are they mistakenly oxidized, they can not intervene, in the further oxidation of the beer (they've lost their potatoes, and shall readily scavenge new ones); are they left in there assumed "virgin" (read reduced- potatoe sated) state, they can prohibit further oxidation (by chucking a few spuds at intended offenders)... to actealdehyde.... er, nope. Not exactly acetaldehyde, which is the reaction we like to name, but it is another very SPECIFIC reaction that they can intervene in, that produces the "wet cardboard" taste, which is NOT acetaldehyde (but may or may not be related to one single 9 carbon unit, however the hell that got in there). I mean really. Do all of you out there have repeated problems with wet cardboard flavours, that HSA must be raised as a banner again and again? My personal experience, is that I spent many years unnesessarily pussy-footing around with my beer after reading about HSA effects (believe it was Miller's first book that had me treating the beer in my kettle like I was putting a quaqdraplegic to bed), and have since found the effect within my set-up to be "insignificant" between a bit of splashing, and escetic reverence. Now if you want to discuss "oxidation tastes", the most sure-fire way I know of sending a beer to an early "old-barrel" grave, is to have a secondary temperature, just a tad higher than your primary, and let the temperature creep up slightly (one degree is plenty) during the secondary. If that beer tastes fresh for ten minutes, I've never caught it (this is a recurrent problem each summer, when using a non electrified lagering cellar, and entails a LOT of carboy shifting). But of course, as radical tasting as this effect is, it doesn't resolve very well into an A-> B model of analysis, and never gets mentioned! Or how about "transport damage"-- I love the Ales in England, but have never tasted one outside of the Island that doesn't have that "edge". Nope, instead HSA get's thumped again and again, as "getting oxygen in causes oxidation" is a much easier concept to understand... even if the actual effects have never plagued the people discussing it (or have they?). Avoiding oxidation in general? I think there are two approaches... The modern industrial; which is to remove all manner of things which might not taste good when oxidized (even if they were terribly interesting in their non oxidized state) or the traditional; this was to keep a supply of the best little reductants available shoved inside the keg, that is, living yeast..... I'd just hate to think that homebrewer's are tending to opt for the first approach. (Hmmm, and I'm usually so silent.... must be the beer I am guzzleing. Couldn't find a glass, but it tastes just fine out of my empty "Nike" box.) Dr. Pivo Return to table of contents
Date: Mon, 11 May 1998 15:45:43 +0000 From: Jim Liddil <jliddil at azcc.arizona.edu> Subject: pH measurements part 2 Decided to do some more experimenting. I used a more "normal" mash thickness of 13 grams of malt in 30 ml of water. I preheated everything including my mash water and mashtun (beaker) to 150 F. I then added the malt and water to the beaker at 150 F and let it go for 30 minutes at 150 F. I took the pH at 150 F and it was 5.41 and the mV reading was 108. I then cooled the sample to 70 F in a water/ice bath (undershot 76 F) and took the pH/mV (5.69/92). The buffer mV for 4 and 7 respectively were 190 and 18. I did this in duplicate and surprisingly the numbers were all the same. Jim Return to table of contents
Date: Mon, 11 May 1998 18:57:20 -0400 From: "Jim & Shelly Wagner" <wagner at toad.net> Subject: Suggestion If you're able to ...before going any further....grab one of your brews, kick back and try to remember why we all started to participate on the HBD. We all have a common bond and there is by no doubt a wealth of experience and knowledge here. Lately it seems a lot of the replies given are either harsh, childish...or both. I do not know nor have I ever met the majority of you in person, and after what I've seen here lately...I'm glad. I have a lot of respect for most of you out there.....I wish I could say that for everyone. Most likely that beer you're drinking right now is pretty well-rounded......maybe it's time you should be. OK....my sermon is over...let's get back to talking about what we love!! Jim Wagner <<<<<<Stoney Creek Brewing>>>>>> **********Pasadena, Maryland******** Established-1994 ~~~~~~~~~~~~ Return to table of contents
Date: Mon, 11 May 1998 21:23:05 -0400 From: Jim Bentson <jbentson at longisland.com> Subject: Thermal Loading & Snide Comments Recently, there has been an "anti-Fix" thread that has been revolving around George Fix's post about excessive thermal loading during boiling. This post lead a few of our frequent posters to make some very general statements that gave the impression that Dr. Fix makes statements based on little supporting evidence and then doesn't follow up on critiques of his work (belied by his response in HBD 2710). I would like to go on the record here as saying that, based on my reading of the many of his peer-reviewed scientific papers as well as the three brewing books he has written and his numerous articles related to brewing, I believe that this certainly does not ring true with what I have found. Dr. Fix is a professional scientist and cites the pertinent technical literature in his work. I have great regard and respect for his contributions to creating a body of knowledge about the science and art of brewing, particularly for homebrewers. To be more specific I would like to comment on the following post as an example of the genre of remarks recently posted. In HBD 2710 the following appeared: snip.... >Dave B. added to the evaportion/"thermal loading" thread: >>My suggestion is let George explain it, if he can. Like >>Scott Murman says, if past behavior is any example - I >>doubt if he will provide any data to back this up, nor comment. >Amen. Marks' MEngr. handbook fails to even mention "thermal loading". The >term has a nice ring to but is deviod of meaning, even when taken in the >context of the posting. end snip... Unfortunately, this reference to the M.E. Handbook might seem to many readers as a validation of the claims against Dr. Fix. It is simply not true. Thermal loading is a common term used in the aerospace and mechanical engineering professions ( among others). Any text, including the 'Heating' Section of Marks Handbook discusses heating loads and cooling loads relative to buildings etc. The term 'thermal load' in a brewing connotation refers to the 'heating load'. The heating LOAD on the wort is the heating RATE delivered to the wort in BTU/hr. Again it is a VERY common term in the thermal science field. Simply stated, the higher the rate of heating the higher the thermal load. In brewing, higher heating rates ( higher thermal loads) lead to a more vigorous boil for a fixed volume etc.. I personally would like to see the level of this discussion return to a discussion of fact not of personality. I have no objection to the correction of real errors. We all make these without exception, but I strongly object to the unspecific type of sniping I have seen of late. Jim Bentson Centerport NY Return to table of contents
Date: Tue, 12 May 1998 03:27:18 +0100 From: "Mort O'Sullivan" <tarwater at brew-master.com> Subject: trans-2-nonenal Dave Burley asks: >I would also like to know more about the science surrounding the >identification of this substance (trans-2-nonenal) and how a 9 carbon atom >compound got in the beer, anyway. Fusel oils? I doubt it. First, the aldehyde you and AlK have been bantering over is properly named trans-2-nonenal, not trans-2-nonenol. It is fairly well established that trans-2-nonenal is derived from fatty acids in the malt, and not from higher alcohols, as you seem to suppose. The basic facts that are agreed upon are: Linoleic Acid (C18:2) . . . (Oxidative degradation, several steps, via trihydroxyoctadecenoic acid) . . . Trans-2-nonenal (distinctive wet cardboard aroma detectable at fraction of ppb) What is not agreed upon is the exact pathway. One school of thought is that an enzymatic pathway involving endogenous lipoxygenase enzymes are to blame, while others believe the primary culprits are oxygen radicals in the wort/beer. Technically, both are possible, but one mechanism is probably more responsible than the other for off flavors in beer (I tend to agree with the latter view as lipoxygenase enzymes are very heat labile and are denatured early on in the brewing process, yet the wet cardboard phenomenon typically is not a problem until much later in the process--but there are good arguments for the other point of view as well). Also note that trans-2-nonenal is not the only degradation product of linoleic acid--just the most studied. There are a slew of other fatty acid-derived aldehydes responsible for stale flavors in beers and other food products. Hope this info helps. - ------------------- Mort O'Sullivan Edinburgh Return to table of contents
Date: Tue, 12 May 1998 13:46:30 +1000 From: David lamotte <lamotted at ozemail.com.au> Subject: Back to Boiling Basics A lot of good information has been presented recently on the effects of excessive evaporation during the boil, but I believe that some basics have been overlooked. Simplifying things greatly, you can think of the kettle as a closed system. The heat generated by the burner must all go into the wort and, the energy is absorbed as an increase in the frequency with which the various molecules vibrate, and we observe an increase in the measured wort temperature. The vibration of some of the molecules on the wort surface cause them to 'jump' out of the liquid and become "water gas" or steam. So the energy from the burner results in both a rise in wort temperature and the creation of steam. Once the wort reaches boiling point, its temperate cannot increase any further so all the applied energy appears as steam, which means that there must be a lot of molecular vibrations going on. Dr Fix has posted that excessive thermal loading during the boil may lead to flavour problems due to the reactions induced, and it does seem logical that the amount of evaporation during the boil should be an approximate measure of how much 'thermal loading' has occurred. Isn't it conceivable that the molecular vibration producing the steam could also facilitate the undesirable Millard reactions, and lead to the flavour problems ? A number of posters believe that the kettle geometry would influence the evaporation rate. This is true if we were only considering the evaporation that occurs when the air (and included water vapour) are at equilibrium with the water surface. When we are applying heat, it shouldn't matter whether we are boiling in a test tube or a shallow pan. The amount of heat applied results in a given mass of water going from a liquid to gas. But then I also agree that it probably doesn't matter much except for the lightest beers. David Lamotte Brewing Down Under in Newcastle, N.S.W. Australia Return to table of contents
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