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15

So it turns out: The proper amount of oxygen dissolved in wort is 8-10 ppm. Shaking typically yields around 4 ppm. It's possible to achieve as much as 8 ppm with plenty of headspace and LOTS of vigorous shaking. As an example, 5 minutes of shaking a 1.077 wort may only achieve 2.7 ppm. Siphon sprayers will be in the same range. Air with an Oxygen Stone ...


13

You should only aerate before the yeast have had a chance to really get going, so that they can consume all of the oxygen that's in suspension. It's really too late now, and will likely result in oxidized flavors. The yeast should be fine for carbonating your beer with simply the priming sugar, though.


9

You'll call forth the legendary dormant beast of HSA! That's hot-side aeration - introducing oxygen into the wort which could cause some compounds to oxidize. At least, that's the myth. HSA is a bit like santa claus, and autolysis, which although real, rarely affects homebrewers. If you splashed the entire wort like this then there's a good chance the ...


8

Aeration post boil and post cooling, but pre fermentation, is a good thing. Aeration post boil, but pre cooling, can result in hot side aeration, which can oxidize your beer. You can also aerate up to about 12 hours into fermentation, but usually not after that point. The point is not to "integrate" the yeast. Yeast use oxygen to synthesize sterols, ...


6

In short, depending on the age of the cake there should be no need to re-aerate the wort for growth purposes. Using the full on yeast cake will make fine beer without the need of extra O2 for yeast growth. The downside to this practice is that without some active reproduction going on you don't always get the true flavor profile of the yeast in the beer. ...


6

To quote from http://www.wyeastlab.com/hb_oxygenation.cfm: It was concluded that pumping compressed air through a stone is not an efficient way to provide adequate levels of DO. Traditional splashing and shaking, although laborious, is fairly efficient at dissolving up to 8 ppm oxygen. To increase levels of oxygen, the carboy headspace can be purged with ...


5

As far as I understand things, the yeast won't go through a serious growth phase in the bottle. The pressure and alcohol make for a harsh environment, and you shouldn't be using enough yeast to really consume any oxygen that you would add. At this point, you really want to avoid oxygenation, so that you limit oxidation flavors in the beer. Thus, you ...


5

If you're concerned about using good practice, you really shouldn't rack fresh wort onto a used yeast cake. The trub contains a lot more than just healthy yeast, and doing this doesn't allow you to control your pitch rate. I know that doesn't really answer the question, but it seems that your general procedure leaves more room for error than the oxygen ...


5

Sloppy Pouring. When my boil's done and cooled, I pour it between the carboy and my bottling bucket a few times, making sure it gets well-splashed. If you're doing a partial boil, you can often ignore aerating the wort, and just pour the extra water around to aerate, then add that to the wort in the fermenter. According to Palmer, this will get you to ...


5

Bubbling really tells you nothing other than CO2 is being released. It's not a reliable indicator of fermentation. In addition, if you ferment in a bucket and have a loose seal you won't see bubbles. Aeration is needed so that the yeast can use the O2 to synthesize sterols to build new cells. Because the cell count in dry yeast is so much higher than ...


5

The carbonation process occurs due to fermentation of the priming sugar. Fermentation is an anaerobic process, therefore no additional O2 is needed for carbonation to happen. You'll pick some up anyway through simply by racking. Excess O2 post fermentation will oxidize the beer and create stale flavors as well.


4

Upvote on the question, and someone will undoubtedly come by with a better answer, but here goes off the top of my head: Acetaldehyde (a-cee-tal-de-hide....nobody says it right!) is a precursor to alcohol. It is an intermediate compound that is formed prior to the formation of EtOH/ethanol during fermentation. So the weird thing is that acetaldehyde is ...


4

If you rack from your brew kettle to your fermentor with some tubing and racking cane you can get a wort disperser. These are little cone like things that go on the end of the tubbing and create a spray of wort as it enters the fermentor. Here is a link to one at NortherBrewer One of these combined with good ole' shaking in the carboy works pretty well for ...


4

My simple perspective on this one is that the oxygenation of the wort provides a catalyst for aerobic respiration stage in the yeast during which they strengthen the cell wall and generally make them healthy, happy and reproductive. Clearly if you are over-pitched, you are less concerned about the reproductive characteristic but you still want the happy and ...


4

The trub will settle naturally as the beer finished fermentation. Don't worry about it. Especially don't try to "fix" it now. That often results in more problems than you originally had. There has been at least one test I know of using wort with trub vs. wort with trub removed. The beer was a pilsner and the conclusion was that the beer with the trub ...


4

Well your aeration method will be more efficient if done while cool. As the warm wort won't hold as much dissolved oxygen. Furthermore, the warmer the wort the faster oxidative (staling) reactions will occur. When I make lagers I chill with my IC down to 65-70F, transfer to my fermentor then put it in my fermentation fridge overnight to get it to 50F ...


4

I would recommend using an anti-foam agent such as fermcap-s http://www.northernbrewer.com/brewing/fermcap-s-1-oz.html or if your LHBS carries another anti foam agent. I have used these with great success in the past to prevent boil overs and also cut down on the mess associated with fermentations that require a blow-off tube.


3

I don't know of any homebrewers that are actually measuring the ppm of O2 dissolved in their wort. The best practice is to get an O2 cylinder with a medical grade flow meter (not a pressure regulator, but a flow meter). Then experiment with time on the meter and good results in the final product.


3

There's a relatively inexpensive procedure, known as the Winkler method, that's used by ecologists to measure the oxygen concentration in streams and ponds. It relies on titration using sodium thiosulfate (among other chemicals). I don't think this test works on wort, however, due to wort chemistry. At the very least, titration would be difficult with any ...


3

It does not need to be 5.00000 gallons, don't worry about the small differences. You can aerate after pitching the yeast, so long as it's immediately after; the yeast need oxygen during the lag phase, but once alcohol starts being produced, you don't want to introduce oxygen at that point.


3

Oxygenating your wort using a tank is leaps and bounds more efficient (as well as more expensive) than agitation or splashing. Simply agitating or splashing your wort to oxygenate it will work for most average gravity beers (you're aiming for a minimum of eight parts per million of oxygen minimum), but will otherwise require a significant amount of effort ...


2

I don't have definitive evidence one way or another, but here's my thoughts on the matter. The two or three times I have pitched onto an existing yeast cake, I have always followed my standard aeration procedure and things have been fine. Good fermentation, etc. My thought is this: If you are going to pitch on an existing yeast cake (setting arguments ...


2

I pour my wort into a bottling bucket and then letting it freefall from the spigot into the fermenting bucket about 2 feet below it. It's easy and it works well for me. I put aeration on the "art" side of brewing as opposed to the "science" side b/c I have no idea how to calculate O2 parts per million in my beer... Also, I watched my buddy "shake" his ...


2

Well the reality is that you need some yeast growth to generate the proper flavor profiles with most all ale yeasts. If you underpitch any given ale yeast vs. super overpitching the ester profiles or main flavor characteristics change significantly. There is an interesting line to be drawn between how much growth and how much esters (etc) however. In the ...


2

I suggest listening to this particular episode of Brew Strong about Hot Side Aeration. It features Dr. Charles Bamforth, one of the foremost brewing scientists who is willing to talk to us homebrewers. He essentially dispels the majority of myths about HSA saying that it is far more important to avoid Cold Side Aeration. (Edit: Dr. Bamforth does not dispel ...


2

Too much oxygen in a starter is almost impossible, so long as you decant the liquid and don't pitch it with the yeast. If you plan to pitch the liquid (e.g. to kraeusen a beer or restart a stuck ferment) then don't stir at all since you'll be pitching oxidized wort. A vortex isn't necessary for oxygen uptake - just having the surface in continual motion ...


1

20C is 68F, which is normal-to-high ale temperature. Why do you think this is "low" for a lager? Lagers are typically fermented at about 50F, give or a take. Also, I wouldn't wait 5 days. You don't have to check the gravity to see if fermentation has started, just take off the airlock and look down into the bucket/carboy through the opening. A clear, ...


1

I agree with what mdma said about HSA, but I'd also like to address the foaming aspect. Foam in beer is formed by a matrix of proteins and carbohydrates. It's been said that these proteins only have the ability to form foam once. If you create too much foam in your wort, you could affect the head on your finished beer.


1

Previously I was mistaken. Yeast do not abide by the same rules as mammalian cells which I am familiar, who prefer aerobic respiration when there is oxygen. Instead when yeast are introduced into the wort (which is over 1% by weight sugar), regardless of the presence of oxygen, they immediately enter fermentation and begin producing ethanol. This is called ...


1

The whole purpose is to get air into the wort, so: This is especially true for a carboy, where there's a smaller opening (so not a lot of wild yeast and bacteria can get in). But even in an open fermentation bucket, as long as you're not splashing it out of there, give it as much as you can, then pitch plenty of yeast, and any wild bugs won't stand a ...



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