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Question: "Piet and I brewed 10 gallons of Weizen together. Thus, the wort was the same, they were cooled to the same temperature and pitched with the same yeast at 75°F (O.G. 1.058). Jim took his 5 gallons home and fermented in a regulated refrigerator/fermenter at 68°F for three weeks. F.G. = 1.014 at 68F° Jim bottled 1.5 gallons of this with 76.5g of corn sugar and carbonated in the bottle for 2-3 weeks at 68°F before entering it in competitions. In contrast, Piet fermented in two steps. The primary was done at ~70°F in a 7-gallon bucket that was sitting on the concrete basement floor (trying to take out access heat) for 8 days. During the first 4 days of primary, the fermentation was very aggressive and yeast/liquid blew through his airlock. Piet had to cover the airlock with a big beaker and clean and replace it each day. The secondary was also at ~70°F in a 5-gallon Better bottle carboy, on cardboard (no longer in direct contact with cold floor) for 13 days. Afterwards, Piet bottled all 5 gallons primed with 200g corn sugar. FG = 1.015 @ 70°F
These two examples both turned out very good but also very different. All that tried them or judged them thought so. Jim's version had stronger banana and lower clove aroma than Piet's. Jim's cloves were present in the taste but not harsh. Piet's were a bit higher cloves in the flavor, especially aftertaste. Our question is, why did they come out so different?"
Master Calvin responds: "The problem answering this one is that we have not just one but a few separate things that were different in the fermentation and racking processes, along with incomplete temperature data for the fermentation, as well as a blowoff problem in one but not the other.
For fermentation, Jim has the better setup, a steady 68°F fermentation chamber. That's not to say that the beer itself was 68°F, and it probably was higher during initial fermentation stages, but at least the process is probably repeatable. On Piet's fermentation, we only know that the beer was 70°F at the start. Who knows what temperature the basement floor was, or how much of an effect the basement floor had versus the (perhaps warmer) ambient air in regards to cooling the wort/beer in the fermenter. For a proper comparison, it would be better to have measurements of the actual beer temperature in each, since the fermentation "chambers" are so different.
I suspect, from an educated guess, that Piet's setup is more prone to temperature swings than is Jim's setup. Jim's refrigerator might do a better job of moderating the internal temperature via better heat transfer if it's a forced air type refrigerator, as compared to what might be nearly still air in the open basement. The overflowing airlock also is an indication that maybe Piet's fermentation was warmer than Jim's, and probably by more than the headline 2°F. And having to clean up an overflow every day is not good, either, from a sanitation point of view. (In this regard, FermCap is a product you can use to control this.)
The second difference: Racking to secondary. I don't personally see a reason to do this for a Weizenbier that is expected to be cloudy anyway, and Jim didn't do it. Racking always increases the chances of infection, though that's hopefully a slim chance in your brewery, yet such an infection from this or other sources can be a cause of increased phenols that could supplement the clove aroma that's already in there. Racking to secondary also increases the chance of oxidation unless you are racking to a vessel (e.g. keg) that has been properly and completely purged of oxygen, and oxygen in the beer is never desirable. I imagine it's probably pretty hard to completely purge oxygen from a Better Bottle as opposed to a keg that you can fill with no-rinse sanitizer and then empty with pure CO2 behind it.
A note about blanketing a container with CO2 before racking: a common homebrew practice is to blast a bit of CO2 into the container before racking, in order to provide a blanket of denser CO2 over the beer. This works, but only partially. CO2 is denser than air, and cold CO2 from evaporation out of liquid is yet denser. But as you blow the CO2 into the fermenter, it mixes to some extent with air and forms an imperfect, high-CO2 layer as it settles, not a pure-CO2 layer. What is less realized is that left for a while, the CO2 completely mixes with the oxygen to form a uniform mixture in the container; they do not separate out from each other. Hence, a quick CO2 blast is a help, but it's an imperfect solution for keeping oxygen away from the beer.
In summary, in the case of these two beers, my guess is that the fermentation temperature was the primary culprit. The fact that Piet's was blowing through the airlock is an indication that the beer could have been fermenting several degrees warmer than Jim's, and this could explain the difference in cloviness that the judges found. Different temperatures with Weizen yeast give significantly different balances of clove versus ester.
In talking with professional brewers just last weekend, one indicated that he kept his temperatures down to reduce cloviness in the balance. This is yeaststrain dependent, though. The effect of temperature is also different for esters versus phenols for a given yeast strain. Not only that, if esters are reduced too much, the balance turns to cloves, and so with some strains (so I have read) the beer might seem clovier than at warmer temperatures just because of the shift in aroma balance. So don't take either "warm=cloves" or "warm=esters" as gospel. Find the temperature that gives you your best result with your preferred yeast strain, and stick with it from then on."
Last modified: September 07, 2016 2:21:46 AM UTC.
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