HOMEBREW Digest #4892 Fri 18 November 2005

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  more esters and "pitch low and let it go" (Matt)
  Re: Home Brewery Pictures, peristaltic pumps (Dylan Tack)

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---------------------------------------------------------------------- Date: Fri, 18 Nov 2005 09:51:08 -0800 (PST) From: Matt <baumssl27 at yahoo.com> Subject: more esters and "pitch low and let it go" A bit concerned that we're wandering off into a 2-person dialogue (especially given the out-of-sequence posts), let me rehash the main ester/fusel points rather than respond line-by-line. Hopefully I don't put words in Steve's mouth: 1. Steve first reported that BY&F says *ester production is independent of ferment temp if oxygen is controlled*. (i.e. temp matters in experiments only because it affects oxygenation.) The book apparently gives no reference with this statement though. 2. I said "this is great--if it's true we only have to worry about *pitching temp and not ferment temp* as far as esters go. We should email the authors of BY&F to ask for a reference." Steve said he would email them after reading the book a bit more. 3. I also suggested that since it's been shown that ester levels have some dependence on fusel levels, if esters are independent of temp then I suspect fusels would also be--otherwise the increased fusels would lead to increased esters. Steve said he didn't think so, for a lot of good reasons, and has fully convinced me that it is possible (maybe even likely) that fusels are dependent on temp even if esters are not. I do still *suspect* that if esters are largely independent of temp then fusels largely are as well, since whatever experiment is used to show the ester result must by necessity control many of the confounding factors Steve mentions, and therefore my original reasoning arouses my suspicion. Anyway, as Steve said, a test is called for rather than more speculation. Anyone have two ales fermenting in the fridge that were pitched yesterday night, and want to take one out? Cause that's all it'll take to get a decent data point as far as taste goes. - ------------ I mainly care about this because it is much more convenient for me to pitch ales (all I make) at a low temp and then let the ferment temp go uncontrolled, than to pitch at a low temp and then control the temp for the whole fermentation. And I want to understand the effects of this practice. >Back to perspective - The one paper indicates a 15% increase in >fusels w/ a 6C increase in temp. The most I've seen in a paper >is a 19% increase over 4.5C and these are without oxygen >control. Perhaps with cool pitching this percentage drops a fair >bit. That's not a show-stopper but be aware that fusels will >*likely* increase with temperature. This, to me, almost makes the point moot. Temp increases of 4.5-6 C are about what you might expect if you "pitch low and let it go," and the numbers Steve gives imply a maximum of 19% increase in fusels. In practice pitching low reduces the average temp in addition to perhaps better oxygenating the yeast, so it will almost certainly mean less than this 15-19% number, perhaps much less. That doesn't sound like a lot to me, for a reasonably well-made beer. As a sidenote, according to the excellent new book _Brew Like a Monk_ the vast majority of Belgian and American producers of high-quality abbey-style ales pitch in the mid 60s and let the ferment temp rise, usually to the mid 70s and not so uncommonly to 80+. Matt Return to table of contents
Date: Fri, 18 Nov 2005 12:18:29 -0600 From: Dylan Tack <dylan at io.com> Subject: Re: Home Brewery Pictures, peristaltic pumps > From: "Randy Pressley" <RANDYP at cityofws.org> > Subject: Home Brewery Pictures > > I thought it would be interesting to see folks brewery setups. Here is my setup: http://genome.uiowa.edu/~djtack/brew I recently made two major improvements to my brewery: a peristaltic pump, and a Superb burner for the boil kettle. Last weekend I brewed a 10 gallon batch of a Guinness clone on my new-and-improved system. There are a few interesting findings to report: After reading about them on HBD, I decided to pick up a Masterflex peristaltic pump. I bought several components separately on eBay, for a total of about $110. I totally love this thing! For those that aren't familiar with them, it works by putting the tubing inside a rotor housing, with metal rotors that squish the tubing, pushing the fluid along. There are several advantages to peristaltic pumps, but the main one in my setup is the flow can be precisely and repeatably controlled (the vendor says +/- 2%). The pump heads can also be stacked, to synchronize multiple channels. So one channel pumps sparge water in (to a Phil's sparger, which I also think is totally cool), and the other channel pumps sweet wort into the boil kettle. The result - a totally automatic sparge! I kept a fairly close eye on the system, but everything chugged along just fine. I could have taken a nap instead. This is light-years ahead of my old system - which required putting our living room furniture on the counter to get the HLT high enough to gravity feed, then constantly fiddling with the valves to control the flow rates, then dragging the boil kettle up a flight of stairs to a borrowed outdoor cooker. Not fun. On to the burner - I wanted to boil in the kitchen, but our wimpy Magic-Chef stove was no way up to the task. I decided to go with the Superb burner. At 35,000 BTU/hr, it is comparable to a household oven, and appeared to be an efficient design, so I figured (hoped) that the carbon monoxide would be manageable indoors. I plumbed it into the propane line that feeds our stove - and it works great! It ran for nearly two hours, with only an open window for ventilation, and the CO meter stayed at zero. I had been a little worried, because others on HBD had reported CO problems with the Superb burner. -Dylan Iowa City, IA Return to table of contents
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