HOMEBREW Digest #4897 Sun 27 November 2005

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  RE: Dilution during fermentation ("David Houseman")
  RE: HBD: Odd final gravity (Steven Parfitt)
  re: Odd attenuation figures (stevea)
  hydrometers - bah humbug ! ("steve.alexander")
  Siebel Advanced Homebrewing Course Dates Announced! ("Lemcke, Keith")
  Lowering CO2 emissions, Cock Ale (mrgoodbeer)

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---------------------------------------------------------------------- Date: Thu, 24 Nov 2005 08:33:13 -0500 From: "David Houseman" <david.houseman at verizon.net> Subject: RE: Dilution during fermentation John, Nothing wrong with diluting more concentrated beers. This is done commercially. You want to use de-aerated water however so as not to introduce oxygen into the beer. Boiling water and sealing it so that it cools without contact to air will work, and sanitize the water you're adding. Also note that the flavor profile of the concentrated beer will be somewhat different than if you'd made the fully diluted beer. Kettle caramelization, hop utilization and ester formation are things to consider. But this is done commercially so you can as well, with success if you consider the variables. David Houseman Return to table of contents
Date: Thu, 24 Nov 2005 21:20:50 -0800 (PST) From: Steven Parfitt <thegimp98 at yahoo.com> Subject: RE: HBD: Odd final gravity David Houseman responds: On Monday, 21 November 2005 at 11:52:05 -0900, Alex MacGillivray wrote: > I don't want to call this a problem because it's really not. I'd just like > a little feedback from the community. > The last several batches of beer I've made, including an oatmeal stout, > have fermented all the way down to 1.010. ...snip... 98.6 is another reference point. David Houseman That number is =/- 1.5 degrees from what I understand. Now, if you know what your idividual normal temp is you can use that. Mine is 97.4 But even that varies from day to day and even during the day. I'd stick with an altitude corrected boiling point and freezing trippel point. Steven Return to table of contents
Date: Sat, 26 Nov 2005 23:53:31 -0500 From: stevea <steve-alexander at adelphia.net> Subject: re: Odd attenuation figures As GregL notes .... >I don't think that it makes sense to mention attenuation without some >idea of the grain (and cane) bill. Exactly an FG of 10 degrees (SG=1.010) may be wonderful or horrible depending on what you started with. Pete Limosani says he gets ... >Brown Ale O.G. = 1.050, T.G = 1.009 >Vienna O.G. = 1.055 T.G. = 1.006 >American Pale Ale O.G. = 1.050 T.G. = 1.005 >Bohemian Pilsner O.G. =1.048 T.G = 1.008. ... >All four of these are 3-10 points lower than expected. The apparent attenuation% values above are: <82%, 89%, 90%, 83%> so there is good reason to have "other" expectations. I'd go farther Pete. All four sets of hydrometer readings are almost certainly erroneous. "Normal" attenuation level for typical all grain 11-15P-ish wort is around 72-77%. Very unattenuative worts for bock beers and such may be down around 65% and very highly attenuative all-grain worts may touch 80-81%. Kunze discusses making "dietetic beer" in which an *extreme* mash regime results in 80-85% attenuation. You cannot obtain 89-90% attenuation from all malt brewing unless you have a high attenuating infection, add enzymes OR have made bad hydrometer readings. It is NOT the result of a little ~62C excursion or some other mashing mistake. Bad hydrometer readings are almost certainly the source of error. Kudos to Spencer (=S rulez). .. more on hydrometers to follow ... -S Return to table of contents
Date: Sun, 27 Nov 2005 05:44:51 -0500 From: "steve.alexander" <-s at adelphia.net> Subject: hydrometers - bah humbug ! A hydrometer is a simple application of Archimedes principle; that the bouyant force on an object is equal to the weight of the displaced fluid. When a hydrometer floats at equilibrium the downward force due to gravity equals this bouyant force described by Archimedes. The mass of the hydrometer is a constant, often controlled by the manufacturer by placing lead shot in a glass bulb, they also affix an "almost constant cross-section area" tube above the expected fluid level for an expected fluid density. For example, I have a cheap circa 1985 beer/wine hydro. It has ~32 gram mass and a paper fiducial graduated over about 12.4cm which relates SG readings from 0.990 to 1.170. The diameter of the tube is 0.8cm giving a cross section of 0.502cm^2. The hydrometer is clearly marked Sp.Gr.,T=60F, indicating calibration to specific gravity against the density of water at 60F. Density is mass per unit volume, while "specific gravity" is the ratio of the density of a material to the density of water(Dw). Water has a density near 1gram/cc, but more on this later. As the hydrometer reaches equilibrium in 60F water we expect the manufacturer has adjusted the paper slip so the 1.000 mark matches the fluid level. This means the submerged volume (below the 1.000 mark) times Dw must equal the hydrometer mass. Since the hydrometer mass is ~32grams the submerged volume of water is about 32cc. Let's call the submerged hydrometer volume at SG=1.000, "V", and the hydrometer mass "M". We also expect that the manufacturer has correctly calibrated the paper markings for other SG values. For different SG liquid the submerged volume times SG*Dw must still equal M. The new volume differs from the SG=1.000 case by A * d, where A is the tube cross-sectional area and d is the upward displacement. The displaced volume is now V - A*d, and the hydrometer mass is still M so the displaced liquid must have a mass of M within a volume of (V - d*A) ... this means a density of Dx = M/(V-d*A) and an SG of Dx/Dw. So the SG marking at a distance "d" down the paper length should be SG(d) = (M/(Dw*V)) * (1 / (1- d*A/V) ) . For my old hydrometer the SG=1.100 reading is about 5.8cm down the paper so then we have SG(5.8cm) = (32gram/(~1gm/cc)*32cc) * (1 / 1 - (A/32cc)*5.8cm) = (1/( 1 - (0.502cm^2/32cm^3)*5.8cm)) SG(5.8cm) = 1/(1-0.09099) = 1.10009, close enough to 1.1 Note that the (M/V*Dw) term is exactly 1.0 (unitless) *if* the paper mark aligns with the liquid surface at SG=1.000 conditions, so the manufacturer can afford to be sloppy with the mass and bulb volume so long as they carefully align the paper scale. Sadly they are not and this seems to be a major source of repeatable error even in lab quality hydrometers. Note this is NOT a linear relationship of distance vs SG, but we can calculate that near SG=1.0, the vertical displacement is approximately dSG * V / A. So for a 1 degree (0.001SG) change the displacement change is about 0.001 * V / A. My cheap hydrometer thus has a displacement of about 32cc/0.502cm^2 = 0.637mm. That's a bit too small to comfortably read - this this one is marked every two degrees (0.002SG resolution at about 1.3mm spacing near SG=1.0). If we want greater resolution form a hydrometer we have two choices - increase the volume V, or reduce the tube cross-sectional area A. This is the approach in my Ertco lab hydrometers which have about twice the volume and half the cross-section, so 4 times the resolution, but note these both features which add to the resolution also increase the fragility of the instrument. I'm afraid that half a degree (0.0005) of resolution is about the practical limit for a glass instrument. Aside from fragility and limited resolution some other problems dog hydrometers. To read a hydrometer correctly one must read the paper slip at the level of the surrounding liquid surface. The liquid may variably 'climb' the tube, depending on surface tension, forming a meniscus and this distorts the view of the paper slip. The entire theory of measurement assumes only the hydrometer a uniform liquid are involved and CO2 bubbles attaching to the bulb surface distort readings considerably. Any dissolved gasses impact SG reading and this isn't accounted. Yeast in suspension has a mass of several grams per liter and since the hydrometer measures the density including the yeast, we are really measuring both. Just to heave another monkey-wrench into ones thoughts, the earths atmosphere has a density around 1.3mg/cc or 0.13% of Dw and this must be accounted for in the instrument design. What we are really measuring is the difference in bouyance above that already supplied by the atmosphere. I assume most hydrometers are merely adjusted to 1.000 in water with 1 atmosphere of air pressure above and this means that readings away from 1.000 of under normal pressure variation will have inherent error on the order of tenths of 1 degree. Temperature is it's own special Gordian knot. The glass exterior of the hydrometer has a very small, but not entirely ignorable temperature coefficient causing the volume to change slightly wrt temperature. For this reason all hydrometers have an operational temperature specification. The fluid, which in our case is primarily water has a very interesting change in density wrt temperature. Water is most dense at 3.98C(~4C) D4=0.999973 . When we get to 60F/15.556C, the density of water has dropped to 0.999014 - almost a full degree lower. The 1964 change in the definition of ml from the volume of exactly 1gm of 4C water to the current definition (1cc=1ml) means that nearly all the technical literature about hydrometers, like the several NBS circulars, is no longer readable. Specific gravity is defined as the ratio of the density of the fluid to that of water at 4C *OR OTHER SPECIFIED TEMPERATURE*. In addition to operational temp, hydrometers have a water reference temp to which they are calibrated. Nearly all US hydrometers are referenced to water at 60F/15.6C. In the UK it appears that beer/wort SG is measured & referenced at 68F/20C. Both read water at spec temp as 1.000, but Plato's tables indicate that the SG of sucrose solutions do not change in proportion to pure water as temperature varies, so the US hydrometer will read several tenths of a degree higher at 12P than the UK/20C referenced hydrometer !! In sum a well designed lab hydrometer may have resolution of about 0.5 degrees, but temp, pressure, gasses, and probably most important, manufacturing tolerances mean that the accuracy is seldom as low as 0.5 degrees. It's rather unlikely that an $8 hydrometer will accurately read to within +- 1degree and +-2degrees is likely. Ideally we'd like to take hydro readings pre-boil, post chill, repeatedly through fermentation and at final kegging. Proper operation of a hydro, including degassing and temperature control, correct reading procedure is, I suspect, seldom practiced. More error. Hydrometers rank right up there with the iodine test as a tedious, error prone, difficult to interpret nuisance of a test. I hate 'em. We may as well see if a witch will float in wort as use these medieval monstrosities, Yes a hydrometer is vintage 18th century technology. -S Return to table of contents
Date: Sun, 27 Nov 2005 17:39:28 -0500 From: "Lemcke, Keith" <klemcke at siebelinstitute.com> Subject: Siebel Advanced Homebrewing Course Dates Announced! I just wanted to let homebrewers know that the 2006 Siebel Institute / Fort Lewis College Advanced Homebrewing course dates have been posted on our web site, and we look forward to another sold-out course next year! The dates for the 2006 course are July 24-28 at Fort Lewis College in amazing Durango, Colorado, and Randy Mosher, Chris White, Chris Graham and the brewers of Durango look forward to hosting the 2006 program. You can see complete course information on our web site at http://www.siebelinstitute.com/course_desc/homebrewing.html , and if you have any questions please drop me a line at klemcke at siebelinstitute.com. Thanks, and I hope we will see you in Durango!!! Keith Lemcke Vice-President Siebel Institute of Technology Return to table of contents
Date: Sun, 27 Nov 2005 21:58:38 -0500 From: mrgoodbeer at juno.com Subject: Lowering CO2 emissions, Cock Ale To lower your CO2 emissions, it should be possible to mash in an active compost pile, then boil in a solar oven. To make a hot pile, use 30 to 40 parts carbon sources (dry leaves, hay, paper, cardboard, etc.) to one part nitrogen (green leafy material, fresh manure, etc.) in layers of a few inches each, with some coarser material for air circulation. Add some garden soil or old compost as you build the pile to inoculate it with microbes. Add enough water to make it moist, but not soggy. It should breath, but when mashing, a plastic cover or a tarp would retain more heat. The pile is a good place for used hops, and spent grain if you don't have livestock. There should be various solar oven plans available online. I made Cock Ale three times from 1988 to 1996, once with chicken, then a couple times with holiday turkey leftovers. It is a strong, somewhat spicy ale with no hint of bird flavor. With long storage a tiny ring of fat collects on the bottle neck at the top of the beer, not a fault, but a mark of authenticity. Here is my recipe from the last time I did it. The Ghost of Thanksgiving Past, a.k.a. Old Wishbone Avian Ale 5 gallons S.G. = 1.057, plus wine & rum Simmer bones & scraps of small turkey ~6 hours with bay, cinnamon, & rosemary on woodstove. Bash bones with a clean hammer on a clean board, enough to expose the marrow. Marinate 3 to 7 days in 1.5 liters dandelion wine (I used Thunderbird once) with 14oz. raisins, 1 tsp. cinnamon, 1 tsp. nutmeg, 1 tsp. cloves, 2 tsp. ginger, 2 tsp mace, 3/4 cup light rum. It amounted to a 3 gallon punch bowl full. Cover with plastic wrap. Stir or slosh the marinade daily. A stainless pot and lid would do instead. Brew an ale: 10 lbs. pale ale malt 3/4 lb. crystal malt 64L 1/4 lb. dextrine malt 1.5L 1 tsp. gypsum mash about 3 hours with a slow rise from 122F to 158F, sparge. Boil 1 oz. homegrown Eroica leaf at 10 min. 1 oz. '' '' " 35 " 11 grams Fuggles pellets 4.5% 109 '' 1/2 tsp. Irish Moss 109 '' end boil 120 '' Cool, add Danstar Nottingham Ale yeast. Rack to another primary on day 10, add everything in marinade bowl. Rack to carboy 3 weeks later. S.G. = 1.020. Added 1/4 cup corn sugar to keep a little action going. Two weeks later, prime with 5/4 cup dry wheat malt extract, add some more Nottingham, bottle. I drank the last bottle about 5 years later, and it was still good. This is a curiosity to be sampled occasionally, like a barley wine. It's more trouble than most beers, but worth doing. Then there was the time an acquaintance strung up a deer in my apple tree and played around with it for an hour and left, and he never came back for it. So I thought, if I have to mess with this thing, I'm taking it all the way. So I cut, wrapped and froze most of the meat, and then made Bambibrau. Some details differed, but it was pretty much the same recipe and procedure. As usual, Tod Lewark between Clarksburg and Fairmont, West Virginia Wine is a constant proof that God loves us and loves to see us happy. - --Ben Franklin The man who worries morning and night about the dandelions in the lawn will find great relief in loving the dandelions. - --Liberty Hyde Bailey, Manual of Gardening, 1910 As he brews, so shall he drink. -- Ben Jonson, 1598 Return to table of contents
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