HOMEBREW Digest #4859 Sun 02 October 2005

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  Re: efficiency ("steve.alexander")
  And another thing ! ("steve.alexander")
  Efficiency ("Chad Stevens")
  Grain Bill and Colour (Alexandre Enkerli)
  re: Hydrometers, Batch Sparging efficiency ("Mike Dixon")

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---------------------------------------------------------------------- Date: Sat, 01 Oct 2005 03:44:29 -0400 From: "steve.alexander" <-s at adelphia.net> Subject: Re: efficiency Ricardo Cabeza arrived at essentially the correct solution on the efficiency issue under the assumption that equilibrium is reached. *If* you sparge forever, then a continuous sparge collects 5-7% more of the extract into the boiler. I have microscopic differences w/ Chad in the details of his analysis; The extract has unaccounted volume, there is no need to calculate mass, since we are only interested in %effic, the 65% assumed efficiency already includes the sparge inefficiency, and some guys named Cauchy & Riemann have a much cleaner means of assessing the continuous case than any Microzaftig Excel sheet could ever produce [fergawdsakes Chad, at least exercise your HB frugality and use the free OpenOffice suite]. The problem is this - reaching equilibrium doesn't happen in a real-world sparge where sparge time is limited. I haven't run the numbers, but the direction of this correction is clear; batch isn't even as bad as Chad calculates. Diffusion of the extract from the grist to the wort takes time, and the rate of diffusion is dependent on the difference in the concentrations, well actually the concentration gradients overall, and so we expect the rate of extraction to fall as the wort-to-grist gradient drops. When time is limited the extraction is stopped, but that terminal rate of extraction (the amount of extract lost by limiting time) isn't the same for batch vs sparge. If we perform a batch vs a continuous sparge over the same fixed amount of time, then the batch will approach equilibrium more closely for each batch, (but at a higher SG, so a bit less efficiently as Chad's calc shows). For the fixed time period continuous sparge, there is less time to approach equilibrium, so there is a relatively greater efficiency drop for continuous as time is reduced. In all, if we limit the amount of *time* available for the sparge, then that 5-7% advantage for continuous will decrease and MAY even become negative(advantage to batch) in the extreme case. To do a proper analysis would require a numerical quantization of the diffusion. I have hopes that John Palmer will weigh in on this topic. I will point out that Chad's numbers are very good HB values for the water/sparge/grist ratios, however traditional commercial UK ale brewing uses more sparge water, up to 9 US gallons total water for the 10lbs ! And this will be used over 3, and possibly ever 4 cycles (first runnnings + 2 or 3 sparges!). Batch vs Continuous is a pointless argument - you can get very good efficiency with either, efficiency so high that your beer flavor will suffer ! I know - I used to seek that extraction efficiency grail; nowadays I seek better flavor, so I try to limit my efficiency. -S Return to table of contents
Date: Sat, 01 Oct 2005 04:26:51 -0400 From: "steve.alexander" <-s at adelphia.net> Subject: And another thing ! Special thanks to Fredrick for noting the recent JIB archives are open again. They had been for a couple years, then they were closed - so three cheers. If anyone thinks the brewing science articles are irrelevant should take a look at the most recent issue of JIB where there is an article on mash viscosity which has relevance to the discussion of extraction efficiency. For many years I have preached the your HB books are wrong and that the increased temperature of mashout has a negligible impact on mash viscosity. There are graphs to prove it in the several articles on mash rheology. http://www.scientificsocieties.org/jib/contents/current.htm -S Return to table of contents
Date: Sat, 1 Oct 2005 09:05:22 -0700 From: "Chad Stevens" <zuvaruvi at cox.net> Subject: Efficiency Ms. Burley (You're always calling us females - brewsters - despite 90% of HBD BREWERS being male ;o) you just had to throw down the gauntlet.... You can talk all the theory you want to, but for ME, in MY system, with the various methods and widgets for fly sparging I've tried over the years (and I realize at 18 years and a few hundred batches, my experience doesn't count for squat on this page) my efficiency is consistently lower with fly sparging than with batch sparging; fly = mid 60's to low 70's, batch = low 80's. And the efficiency I get with batch sparging is more consistent. Just dump the water in, mix, let it sit for ten minutes, run it off. Simple, no muss, no fuss. You can talk all the theory you want to, but I know from experience what works best in my system. For what it's worth (I still love ya man!), Chad Stevens QUAFF San Diego Return to table of contents
Date: Sat, 1 Oct 2005 12:41:08 -0400 From: Alexandre Enkerli <enkerli at gmail.com> Subject: Grain Bill and Colour Already sent a private message to Darrell about this but maybe it could be discussed here. Darrell was asking about using > the pils so as to get the lightest (if you want it), and use dark > malts to add color and flavor It might not be what he had in mind but it reminded me of the practice of some brewers (including pros) who add rather large amounts of very dark malts to a grain bill which would produce a rather pale beer instead of using the whole palette of malt types with just a touch of darker grains. Randy Mosher's /Radical Brewing/ contains recommendations on developing complex grain bills and it's hard to disagree with him that such a grain bill provides depth and complexity. Tried a few porters recently and they all tasted like a bunch of very dark malts were added to the base malt with nothing in between. These beers often have a rather harsh roasty character instead of a round overall maltiness with roasty highlights. Can't say these beers are incredibly interesting. Those brewers may have gotten the colour right, but they might as well put food colouring in a pale ale. Of course, it's cheaper to dump roasted barley in the wort than to mash many different grains, which might be a reason why some breweries use so much dark malt. It's harder to control a complex grain bill. But different malts can contribute a lot to the finished product, including mouthfeel, depth, and complexity. Some malt flavours may hide other flavours but, more interestingly, some combinations produce a completely new flavour which couldn't be achieved any other way. In fact, even hop-heavy beers can benefit from a complex grain bill. The malt flavours complement the hop flavours instead of competing with them. Thoughts? Alexandre http://dispar.blogspot.com/ http://www.livejournal.com/users/enkerli/ http://blog.criticalworld.net/ Return to table of contents
Date: Sun, 2 Oct 2005 14:09:18 -0400 From: "Mike Dixon" <mpdixon at ipass.net> Subject: re: Hydrometers, Batch Sparging efficiency In a previous digest Ricardo Cabeza demonstrated a mathematical calculation for batch sparging and an excel sheet output he uses for fly sparging. The biggest problem with the calculation was Chad calculated batch sparging on a no-sparge process. All water added to the tun in one large quantity. A batch sparge process would add sparge water in batches, or more than one addition, most times people do TWO batches. The calculation was not performed for that, and other than through experience I am not sure how it could be. Now as far as batch sparging creating a greater efficiency than fly sparging, that would only be possible if the fly sparging process was channeling at some point during the sparge or if the fly sparging process was performed too fast for the sugars to be rinsed from the grains. Both of which could certainly be the case. I have not batch sparged enough to see a definitive increase or a decrease in efficiency as compared to my fly sparging efficiency. However the beauty of batch sparging for the homebrewer as I see it, is the ability to obtain the wort as fast as the valve and plumbing on your tun will allow during and after the vorlauf. It also does not allow channeling so a single outlet filter point is all that is required due to the homogenous nature of the tun. One final note would be from Chad's later posting in point #2 about most homebrewers using Phil's sparge arm. No offense to Dan, but it is certainly not required to perform a fly sparge and I know very few people that use one. Just perf up some foil, place it on top of the grainbed and sparge away. If the homebrewer than changes the batch sparging the foil idea can go along for the ride... Cheers, Mike Dixon Wake Forest, NC www.ipass.net/mpdixon Return to table of contents
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