HOMEBREW Digest #5232 Tue 25 September 2007

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  re: Esters/4VG/N2 ("steve.alexander")
  Nitrogen ("A.J deLange")
  4vg (clove) production ("Spencer W. Thomas")
  Re: Stella Artois ("Doug Hurst")
  Effect of dissolved extract on volume (rather geeky) ("Bill Pierce")

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---------------------------------------------------------------------- Date: Tue, 25 Sep 2007 04:43:34 -0400 From: "steve.alexander" <-s at roadrunner.com> Subject: re: Esters/4VG/N2 Richard Lynch asks, > > -S, You when you wrote about the downside of > >underpitching, you mentioned that there are other ways > >to produce flavors from a yeast, that we must "torture > >our little buddies". Could you (or anyone) elaborate > >please? > > > > > You can find all the detail in the archive, but the short course is .... Yeast produce a majority of their esters right at the point where they get the signal they are running out of a some required nutrient. The yeast metabolism shifts from growth to maintenance fermentation and some storage carbo accumulation. The half-built fatty (short chain) acids the yeast were constructing for growth/reproduction are not only unnecessary but toxic. Perhaps for this reason the yeast produce a burst of enzymes just as growth ceases which, together with some energy and the abundant alcohols convert the fatty acids to esters, The esters are more soluble and less toxic. The same enzymes that esterify these short & medium chain fatty acids(carboxylic acids) will also esterify very short carboxylic acids like acetic acid.in beer together with the various fusels and so produce the aromatic esters in beer. Yeast produce some esters all along, but there is a big rise just as the fermentation trails and yeast growth stops, but of course the ester production spike requires that the yeast are producing fatty acids, that they have energy and that the normal levels of fusels and acetic are available. Adding fatty acids to the wort (or including excess trub) means the yeast don't need to produce FAs so far less esters. If carbohydrates (fermentable sugars) are the first growth requirement that yeast run out of then they may be energy deficient and produce less esters. If you underpitch then the pitched yeast - even if well aerated - will not have sufficient sterol and UFA to divide & grow until the end - so they will produce abundant esters (but maybe also not finish dry).. If you under oxygenate at a normal pitch rate, then again the yeast run out of sterols and so produce esters, but it's more likely IMO that the larger yeast mass will finish the sugars even if slowly. If you overoxygenate then you generally get less esters unless you run out of amino acids needed to fuel growth. The enzymes involved are very temperature sensitive so if you arrange to have the fermenter temp rise as the fermentation trails then you get more esters and also a more rapid finish. It's a rare event to have insufficient fusels and simple carboxylic acids to drive the process. Generally speaking the two most prominent cause of the cessation of yeast growth (reproduction halts but fermentation continues) in malt-wort are lack of sterols (derived from oxygenating the yeast) and lack of wort amino acids after the yeast have used these up. So my opinion is that using clean wort (no trub) boosting the mid-ferment temps and reducing aeration of a normal amount of yeast is a better method for more esters than is underpitched. At least be very careful about the extent of underpitching if you choose that approach. Yeast varieties are quite variable in the specific esters they produce and their ratios and amounts - so do select your yeast for ester aromas. > >I recently brewed a Hefeweizen using Wyeast 3068 and > >am a little disappointed with the results. It just > >doesn't have much of the intense yeast-aroma and > >flavor "kick" that says Hefeweizen. I fermented > >around 67F, pitched a quart of slurry from a > >propagator pack. I'm new at Hefewiezens, and would > >love to be able to make a Paulaner clone, any pointers > >would great, thanks! > > > > > 67F is pretty cool if you want esters, and you want big esters in a hefeweizen. I'd readily pitch at that temp, but slowly plan the temp rise to 75F or even 80F as the fermentation trails off, then back down. The 4VG clove flavor is the result of a yeast metabolism of ferulic acid. Wheat has more ferulic than barley and is released at or under low saccharification temps in the mash. I've heard reports that 4VG production is also temp dependent (more at higher fermentation temps) but that's uncertain. 4VG declines over a period of months at beer storage temps so hefe's are usually best fresh. Weizen yeasts seem to autolyze rather rapidly - so getting the beer off the yeast within a couple days of the mark is important. - -- > >Subject: Nitrogen in carbon dioxide cylindeers? > > > Although nitrogen is used in a mix when serving certain beers like Guinness, the literature claims that nitrogen destroys hop flavor in beer. I find this a bit surprising since nitrogen is so inert but .... -S Return to table of contents
Date: Tue, 25 Sep 2007 12:55:42 +0000 From: "A.J deLange" <ajdel at cox.net> Subject: Nitrogen The critical temperature of nitrogen is 126 K (about -147C) which means that at room temperature it cannot exist as a liquid no matter what the pressure so that consideration of vapor pressure does not apply. The good news is that the indicated pressure relative to the pressure when the bottle was full tells you how much remains. For example if originally filled to 14 MPa half the gas has been consumed when the gauge reads 7 MPa. The bad news is that one cannot get much into a small bottle because the compression ratio is approximately the ratio of the cylinder pressure to apmospheric pressure. 14 MPa (approximately 2000 psig which is a typical fill level) is approximately 140 atmospheres so that each cubic foot of bottle capacity holds approximately 140 cubic feet of gas at room temperature. A bottle of beer mix the size of the typical 5 pound CO2 bottle will thus push a keg or two of beer as opposed to dozens of kegs from the same size CO2 bottle. As pointed out no-one pushes beer with straight nitrogen. The beer would be flat and unappetizing. What people do use is "beer mix" which is typically 60% CO2 and 40% nitrogen or "stout mix" which is 25% CO2 and 75% nitrogen. In both cases the object is to have some CO2 dissolved in the beer but to use the pressure of the nitrogen to drive it through long lines and/or through the "sparkler" in a stout or ale faucet thus producing the creamy head which is a must for Irish Stout and a desirement for other ales. I serve some lagers on mix as well. In the US (don't know about Oz) CO2 equipment and N2 equipment (regulators, hoses, connectors) are of different types specifically to prevent installation of one type of gas in a system intended for another). There is no fundamental reason that a CO2 bottle filled with nitrogen to below its working limits shouldn't be safe if allowance is made for pressure increase as temperature rises. In the US, however, a supplier would probably refuse to fill nitrogen (or any gas other than CO2) into a CO2 bottle. For starters his filler wouldn't match the CGA 320 connector found on all CO3 bottles here. Try a welding supply outfit. They should have CO2. In the states many of them have beer mix as well but it's expensive and it doesn't go far as I noted above. A.J. Return to table of contents
Date: Tue, 25 Sep 2007 10:54:39 -0400 From: "Spencer W. Thomas" <hbd at spencerwthomas.com> Subject: 4vg (clove) production The cloviest weizen I ever tasted was fermented at 62F according to the (professional) brewer. I forget now which yeast she used, but it was one of the "usual suspects." This beer had almost no banana and a huge clove profile. Personally, I liked it, but it was definitely outside the normal weizen range. Some others on this list may have tasted it -- it was brewed at Dragonmead and was on tap during the MCAB judging that was held there a couple of years ago. =Spencer in Ann Arbor Return to table of contents
Date: Tue, 25 Sep 2007 13:25:35 -0500 From: "Doug Hurst" <dougbeer2000 at gmail.com> Subject: Re: Stella Artois When I visited the brewery, there was a display with a sample of each of the ingredients in the sterile brewhouse. I can tell you to skip the crystal malt, add some rice adjunct and use a Northern European, Danish, or Carlsberg yeast strain. I'd stick to Saaz but don't bitter or aroma as highly as a Czech pils. I don't think they're dosing with solid hops, favoring the extracts instead. Hope this helps, Doug Hurst Chicago, IL Return to table of contents
Date: Tue, 25 Sep 2007 18:26:23 -0400 From: "Bill Pierce" <BillPierce at aol.com> Subject: Effect of dissolved extract on volume (rather geeky) I have a brewing spreadsheet, and occasionally I consider adding another bell or whistle to its various sections. This time I thought it might be interesting to calculate the weight of the spent grain, which led me to another issue altogether. During mashing a significant portion of the grain is converted to sugars that are dissolved in the runoff and ultimately boiled in the kettle. This reduces the weight of the grain, although not quite equal to the added weight of the absorbed water in the mash (if you do the mash you will confirm this). Of course the extracted sugars increase the weight of the runoff and the wort. But they also have an effect on volume. As extract brewers, we probably encountered the fact that when we dissolved the extract in the hot water there was an increase in volume (adding to the risk of a boilover if the kettle is not large enough). In the case of liquid extract we may have attributed the increase to the fact that LME is typically 20 percent water. But the phenomenon also occurs with DME, which has a very small moisture content. The amount of the increase is measurable. While the formula is not quite linear due to molecular interactions, the average figure I found (I wish I could recall the source; it's lost to me now) for the gravities typical of wort is that each pound of sucrose (or other sugar) adds 9.48 US fluid ounces to the volume (61.4 ml for each 100 grams, for the metrically inclined). As an example, consider a standard 5 gallon extract batch with 6 lbs. of DME in 7 gallons (pre-boil) of water. With an extract potential of 1.045, DME has 97.38 percent the extract value of sucrose (extract potential 1.04621). In terms of extract points, 45/46.21=0.9738. Multiplied by the weight, that results in the equivalent of 5.84 lbs. of sucrose (6*0.9738). To determine the weight of the water, multiply the volume of 7 gallons by 8.32487 (the weight of 1 gallon of water at standard temperature and pressure, according to a chemistry manual), for a total of 58.27 lbs. Add the weight of the sucrose equivalent for a total pre-boil weight of 64.11 lbs. (58.27+5.84). Calculate the extract percentage by weight; the value is 9.11 degrees Plato (5.84/64.11*100), or a specific gravity of 1.0364. As for the volume, the additional 5.48 lbs. of extract will add 51.62 fluid oz. (5.48*9.42) or 0.403 gallon (51.62/128), resulting in a total volume of 7.403 gallons (7+0.403), an increase in volume of 5.76 percent (0.403/7*100). If we check our math by calculating the gravity using the traditional method of gravity points, we have a specific gravity of 1.0364 (1+(6*45/7.403/1000)) or 9.11 degrees Plato, the same value we calculated for the percentage of extract by weight. In addition to the dissolved extract increasing the pre-boil volume, there is another implication for the all-grain brewer. The usual method of achieving the correct pre-boil volume is to calculate the target and sparge the grain until it is reached. It's possible (and relatively common practice) merely to prepare enough hot sparge water to ensure this occurs. But some brewers (and much of the brewing software out there) also calculate the total volume of water needed for both mashing and sparging. Now my question is whether the calculations and software account for the increase in volume due to the dissolved extract. So far as I can tell, all of the brewing software water-needed calculators do not. If we use the above example of a target pre-boil volume of 7.403 gallons, the sparge water volume should be reduced by 0.403 gallon. Otherwise, unless the brewer measures and monitors the pre-boil volume, he or she is likely to be oversparging. I'm wondering if there are any errors in my thinking and why the software many of us use doesn't account for this factor. While the error isn't extreme, neither is it insignificant. Brew on! Bill Pierce Cellar Door Homebrewery Burlington, Ontario BillPierce_(at)_aol.com Return to table of contents
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