HOMEBREW Digest #4402 Mon 17 November 2003

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  Plastic vs. glass FG/Congrats to Pacific Gravity ("Chad Stevens")
  Non-digest version? ("Greg 'groggy' Lehey")
  Re: Refractometer specific gravity conversion ("Greg 'groggy' Lehey")
  re: Refractometers (Michael Owings)
  slightly OT- sparkling wine (Mike Ward)
  link of the week - Nov 15, 2003 (Bob Devine)
  RE: origin of Hops (Don Van Valkenburg)
  RE: bottle washer ("Jim Yeagley")
  cloudy beer with Wyeast 1028 ("Dave Burley")
  brewing habits (Darrell.Leavitt)
  Corny keg cleaning ("Jeremy Lenzendorf")

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---------------------------------------------------------------------- Date: Fri, 14 Nov 2003 20:24:16 -0800 From: "Chad Stevens" <zuvaruvi at cox.net> Subject: Plastic vs. glass FG/Congrats to Pacific Gravity Recently someone posted they observed a consistent 2 point disparity between side by side glass and plastic fermentations. I had noted the same 2 point difference on a couple of glass/plastic (I've only done a couple) ferments but had disregarded the phenomenon as anomolous. I have had the same (or greater) disperity in side by side glass/glass and plastic/plastic fermentations. What's interesting is that, while the gravities at the end of primary may diverge, they always seem to converge by the end of secondary. For example: side by side five gallons per pale of the same batch, 1.076 OG, WLP 510 Bastogne yeast, intentionally oxygenated one pale, no o2 for the other. After 14 days o2 pale was 1.024, no o2 pale was 1.032 (even more robust effect than I anticipated). After 14 days in secondary, both halves of the batch were at 1.022 FG. No major differences in ester profile noted by the way. Could it be that his plastic ferments received better oxygenation than his glass ferments? Steve Alexander and I have had some offline chat regarding this and Steve's (typically) exhaustive input follows. My assumption was that, because yeast can pump out some heat and because plastic is marginally less thermally conductive than glass, the plastic ferments run warmer and as a result attenuate slightly more. I'm not certain Steve's number crunching bears this out. Has anyone taken temps on side by side identical glass/plastic ferments? What do y'all think? Chad Stevens QUAFF San Diego P.S. Congrats to Pacific Gravity for taking QUAFF's title as California Homebrew Club of the Year! Well deserved. - ----------------------- Steve's stuff: In fermenting 1.050 wort how much heat is generated ... Let's assume the wort ferments to 73% apparent attenuation. This translates to approximately [0.81 * 73] 59%. The rule of 81% is just an approximation and the real value for a mostly anaerobic fermentation will be pretty close to this. 1/ 59% of the extract was fermented or used as yeast biomass. 1.050 wort has a Plato of [ (258-(205*SG-1)) * (SG-1) ] or 12.4P. So the common brewing myth is that the extract has the same properties as a sucrose solution (Plato studied sucrose sol'ns). So 12.4% of the WORT mass is extract. 1Liter of water at 20C weighs 998.23gm and the wort weighs 1.050 times as much or 1048.1gm/L. This means that the wort has [0.124*1048.1] or 130gm/L of extract 2/ This wort has 130gm/L of extract. 3/ (fm 1/ & 2/) the yeast uses 76.7gm/L of extract. Balling's empirical formula is that anaerobic fermentation involves: 200gm carbos + 1 gm Nitrogen compounds => 10gm yeast + 97.5gm EtOH + 93.5gm CO2 So 201gm of extract produces 97.5gm of Alc and 93.5gm of CO2 Ignoring a tiny bit of water used to hydrolyze maltose etc, this means that 191 gm of the 201gm of extract was fermented (95.0% of the lost extract is fermented). The other 10gm (9 of carbs, 1 of nitrogen cmpds) end up a yeast trub. 4/ 72.9gm/L of extract was fermented (95% of 76.7gm/L) and the remaining 3.8gm/L of extract is used for yeast biomass and consists of 0.38gm of nitro-stuff and 3.42gm of carbs. Glucose fermentation releases 0.59kJoule/gm. M&BS states that yeast biomass carbos (90% of the extract used for biomass) releases about 6kJ/gm. The fermentation and the more exothermic yeast biomass energy release (72.9gm/L * 0.59kJ/gm) + (3.42gm/L * 6 kJ/gm) or 5/ 63.5kJ/L is the heat produced with about 2/3rd from fermentation and 1/3rd from yeast biomass carbos! One small (gram) calorie is 4.184 Joule so this is sufficient heat energy to raise the fermenter temp by 15C [[63.5kJ/L / 4.184kJ/kcal] if you fermented in a thermos bottle !! - ----------- But wait! There's more! - ----------- I had an offline conversation with the poster and he was using plastic pales with loosely attached lids. I expect the plastic fermenter yeast were getting more oxygen - and it doesn't take much to make a difference - especially if you underpitch like most HBers. Plastic is a poor thermal conductor, but so is glass. Apparently neither one is such a good insulator so as to make much difference! (this surprises me). Soda glass has bulk thermal conductivity about of 1.35W/m/K while HD polyethylene is about a third that ~0.4 or 0.5 W/m/K. Many other plastics are much worse thermal conductors around 0.1 to 0.2 W/m/K. My hunch is that plastic buckets are a fair bit thinner than the glass but with a comparable total surface area. All told the pale is a better insulator but probably only by a factor around 1.5 or 2 times. The plastic pale should ferment farther above ambient temps than glass - but by how much ? We can ballpark the surface area of a carboy or bucket at 0.6m^2 or more and the thickness at 5mm or less. This means it would take at least (1.3*0.6/0.005) or 150 watts to maintain a 1degreeC(K) difference across the glass surface and at least 50Watts for the plastic bucket. These are low-ball estimates. A comparable sized aquarium can be maintained even 10C above ambient using a 25Watt aquarium heater. I've used a ~25W aquarium heater in a 5gal pale to maintain a ~18C difference (I was culturing lacto's using the pale as a ~100F water bath). So what is wrong ? Obviously the temperature drop across the pale/carboy itself is much lower than 1C since the power flux is so low. Somewhere else in the 'system' the wort is even more well insulated from the ambient. Poor connection to the air I think. If I'm close and a 25W heater can maintain a pale fermenter 18C above ambient then the thermal RESISTANCE of wort to environment is 18C/25W or 0.72C/W, but we calculated that the glass is only about 1C/150W or 0.007C/W or less and the plastic fermenter is about 0.02C/W or less. Thermal resistances are additive so these fermenters are a relatively small part (a few percent) of the thermal resistance of wort to the ambient environment. The takeaway is that wort temperatures really should rise significantly due to heat of fermentation & yeast growth. The difference in wort temp in glass vs plastic is pretty small. The temp differences above ambient should be only a few percent higher in a plastic pale. A 1/2 inch coating of styrofoam would be necessary to double the wort to ambient temp difference and this would provide abt 35 times the insulation as a plastic pale ! You could ferment in thin copper and you still wouldn't drop the temperature much. I think I'll perform an experiment or three and verify and quantify the results. Should be fun. -Steve Return to table of contents
Date: Sat, 15 Nov 2003 16:54:23 +1030 From: "Greg 'groggy' Lehey" <grog at lemis.com> Subject: Non-digest version? I've just subscribed to this digest, and I'm very impressed by the professional standard of most postings. It's a thing I'd like to read more often... only: I hate digests! It's a real pain to get a thread intermingled with other topics, and it makes it very difficult to follow the discussion. This is the only list I know which is available in digest-only form; couldn't people have a choice of digest or individual messages, like with other lists? Before you say "talk to the list administrator", the reason why I'm sending this to the entire list is because I suspect that there are plenty of other people out there who'd also prefer individual messages. Greg - -- Finger grog at lemis.com for PGP public key. See complete headers for address and phone numbers. Return to table of contents
Date: Sat, 15 Nov 2003 18:00:59 +1030 From: "Greg 'groggy' Lehey" <grog at lemis.com> Subject: Re: Refractometer specific gravity conversion On Thu, 13 Nov 2003 06:17:03 -0600, bcarpenter wrote: > William Frazier writes: > >> Bob Hall has had poor results using a refractometer to determine the >> specific gravity of wort "So what's the deal? Any tips from >> refractometer >> users would be appreciated." > > While the subject is on the table, is there such a thing as a quick and > easy chart to show refractometer readings with a corresponding specific > gravity number? > > All I have been able to locate is (for me) a very complex math formula > for conversion. I am an artist and gosh darnnit, it's just over me > head. Take a look at http://www.lemis.com/grog/brewing/Brix-to-SG.html. It's based on one of those formulas, and it assumes pure sucrose (cane sugar) solutions in each case, not maltose or dextrose. For maltose, the Brix values will be about 2.5% too high. Also, SGs measure weight, not sugar, so there's no really accurate conversion for worts. Greg - -- Finger grog at lemis.com for PGP public key. See complete headers for address and phone numbers. Return to table of contents
Date: Sat, 15 Nov 2003 11:35:57 -0600 From: Michael Owings <mikey at swampgas.com> Subject: re: Refractometers I use one of these routinely, and have had greate results. Like Jeff Renner, however, I used to have issues caused by evaporation when I tried to use the refractometer during the boil. Cooling the sample fixes the problem (I use a method similar to Jeffs). It's really a great way to monitor the gravity of the wort during the boil and only takes a few seconds or so to get a reading. Lewis Bonham's published equations work well for determining gravity during fermentation, however I have found that using my instrument the readings tend to be low by 2-4 SG points (about .5-1P) as checked against a narrow-scale hydrometer. Typically, I split the difference and add a fudge factor of around 3 SG points when interpreting the results. This fudge factor may vary with the instrument used and/or brewery, so YMMV. Promash has a calculator built in which works quite well for determining gravity during fermentation using a refractometer. I also have a program I wrote a while back (before this feature was built into PM) that calculates the same thing. If there's any interest, I can post it on my website. I use the "truncated" version of the equations published on the HBD a while back, but the results are pretty close to the promash calculator. Hope that helps -- m ==== Teleoperate a roving mobile robot from the web: http://www.swampgas.com/robotics/rover.html Return to table of contents
Date: Sat, 15 Nov 2003 15:17:05 -0500 From: Mike Ward <mikey at aei.ca> Subject: slightly OT- sparkling wine Sorry for the OT post. My usual sources of info are dry on this one. Alongside my three beers taps, I have separately carbonated 20 litres of dry white wine in attempt to provide sparkling wine on tap for SWMBO. To get a champagne-type level of carbonation, 30 psi keg pressure seems to be required. So far so good. When dispensing at this pressure through a typical tower style tap, obviously I just get a gusher of foam which eventually settles into a glass of now flat wine. I have tried putting up to 15 feet of restrictor tubing (all refrigerated) in attempt to drop the dynamic pressure at the tap to a level that won't gush. No joy. I spoke with a gentleman in the keg business (kegman) who advises that kegging wine cannot be done, and went on to say that I was poisoning myself with lead being leached out of the tap................ Any ideas how to avoid the gushers? TIA Mike Fellow MontreAler to Alex and John Return to table of contents
Date: Sat, 15 Nov 2003 13:58:06 -0700 From: Bob Devine <bob.devine at worldnet.att.net> Subject: link of the week - Nov 15, 2003 Let's say you like beer and have access to an expensive photomicrographic system. What would you do? ;-) http://micro.magnet.fsu.edu/beershots/beerphotos.html http://micro.magnet.fsu.edu/beershots/index.html If you don't think beer pictures are enough, here are more: http://micro.magnet.fsu.edu/cocktails/ Bob Devine Return to table of contents
Date: Sat, 15 Nov 2003 13:23:01 -0800 From: Don Van Valkenburg <brewing at earthlink.net> Subject: RE: origin of Hops This is an excerpt from an article I wrote for Brewing Techniques in 1995: "The hop, or Humulus lupulus (lupulus: a little wolf, alluding to the tenacity with which it clings to any support), is native to three major continents: Europe, Asia, and North America. Hops are classified in the plant family of Cannabaceae, which includes the genera Cannabis and Humulus . The genus Humulus includes two major species: Humulus lupulus and Humulus japonicus (an annual Japanese hop that produces few resin glands and is of no value to brewers)." The complete article is at: http://calferm.org/edu/hops/Pedigree.htm Don Van Valkenburg Return to table of contents
Date: Sun, 16 Nov 2003 07:37:17 -0500 From: "Jim Yeagley" <jyeag at core.com> Subject: RE: bottle washer Using an old dishwasher is a great idea, but be sure to disassemble everything leading to the pump and thoroughly clean/sanitize. Seems there's a screen down in the bottom that protects the pump from chewing on various foodstuffs. If your washer is as old as the one I tried using, there's probably a good collection of nasties just waiting to spoil a good batch of homebrew. I ran hot water into it, mixed in an abundant amount of sanitizer, ran the heater to dry the bottles, and the nasties still won out. Might even be worth replacing the pump and hoses for good measure? Jim Yeagley Return to table of contents
Date: Sun, 16 Nov 2003 13:06:03 -0500 From: "Dave Burley" <Dave_Burley at charter.net> Subject: cloudy beer with Wyeast 1028 Brewsters: Tim writes that his first in a series of house reds was cloudy and the following batches reusing the same yeast recycled were clear. He remembers a similar past problem and he wonders if it was a yeast problem. Assuming that there is not a brewing problem, then the possibility exists of unflocculated yeast which could cause cloudiness which didn't appear in later brews when Tim collected the flocculated yeasts for his next brews. He effectively selected out the non-flocculating strain. A gelatin treatment on a sample of the first batch will perhaps show if the problem is unflocculated yeast ( clears with gelatin) or a starch problem ( black with iodine treatment). London breweries ( from which Wyeast 1028 is derived) in the good old, bad old days commonly used a blend of sometimes 4 ( or more) types of highly flocculant yeasts for flavor and non-flocculating yeasts ( so fermentation stays active and all yeast stirred up) to finish off the fermenation quickly. The non-flocculating yeast would, of course, explain the cloudiness as it would not fall out of the beer quickly. If this is the case, try chilling the beer or adding gelatin or other fining agent ( perhaps Isinglass from Sturgeon swim bladders to be traditional) to clarify it. If you want to preserve something like the original mixture then start with a fresh sample of 1028, skim the fermentation shortly after the rocky head develops to remove preciptiated protein, hops and such detritius and then a day or so later skim and preserve this skimming to start a new brew as they did in the olden times. Keep on Brewin' Dave Burley Return to table of contents
Date: Sun, 16 Nov 2003 13:51:00 -0500 From: Darrell.Leavitt at esc.edu Subject: brewing habits ...brewing a batch of "Chocolate Saison" today (a porter grain bill with a Saison yeast [4th use...]) and I got to thinking that we need to break free of our brewing habits. That is, while some things seem to work for us, we should not be comfortable in the belief that they should be applied across the board, as it will, with every batch. We need an inner brewing revolution of sorts ,...a re-evaluation of techniques that allows each brew to be genuinely new. In other words, if we come to the new brew session ... with old brew habits..., then we have neither broken free of habit.,...nor brewed a unique or new beer. Here is an example,...to bring it down a bit: Irish Moss: is there really any reason to add it (last 15 min) to a porter, or a stout? This is a habit, a brewing habit, that ..., while not making me a bad guy, or a bad brewer, may not be needed for this style. Anyone have any ideas as to why one should use Irish Moss in a porter. or a stout? Other brewing habits ....perhaps on the surface, equally innocuous,... should be discusssed here...at least among those who are serious about the hobby in particular ,...and their own habits in general. ..Darrell Return to table of contents
Date: Sun, 16 Nov 2003 18:37:33 -0600 From: "Jeremy Lenzendorf" <jlenzendorf at progeng.com> Subject: Corny keg cleaning Hello all, I have been given two given two Pepsi ball lock Corny kegs. The only problem is they have chlorine and/or calcium residue in them (they were used in a farm milkhouse). What can I use to safely clean them so they are beer-worthy? TIA, Jeremy Lenzendorf West Bend, WI Return to table of contents
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