When they say 'adequate aeration'...isn't that dependant on pitch rate? It seems if you pitch enough yeast that NO aeration would be 'adequate'.
Absolutely. The commercial brewery pitch rate is typically 10x what homebrewers pitch. So, oxygenation is of little concern once they build a large yeast slurry. For homebrewers, who underpitch 99% of the time, oxygenation is extremely important to achieve a proper cell count.
A popular thread title in this forum is "24 hours and no airlock activity", which is usually the result of grossly underpitching, pitching poorly stored yeast, and/or poor oxygenation.
Homebrewers can achieve a commercial pitching rate by reusing the yeast cake from a previous fermentation within a couple of weeks. The rule of thumb is 25% yeast viability loss for every week at room temperature.
Quote:
Originally Posted by SpanishCastleAle
I have a question about pure O2 and contamination. Below are some links to an experiment that was done in which a bunch of people brewed the exact same recipe but used whatever equipment/process they typically use. If you look at the results table it summarizes the results and the brewers that used pure O2 fared extremely poorly wrt infections.
Sorry, you can't draw conclusions from a small study with that many uncontrolled variables. Probably just coincidence....Perhaps they had a sale on oxygen kits that month.
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In that one study, there is an obvious positive correlation between O2 use and contamination but it can be attributed to so many other things. Maybe they don't clean their stone well enough. It could have been picked up in any other post boil equipment. I wish they gathered chiller type data too because those with O2 may be more likely to use a plate chiller.
Does Pedio reproduce using oxygen like yeast does?
Some other interesting correlations that I got from playing with the table in excel (maybe they write about them in the article but I haven't read it yet):
15 of the 35 had severe contamination (42%).
Of those, 9 were hit with O2 while 6 used "other" methods. Really, that's only a 60/40 split and a pretty small sample size.
There's a much higher correlation between severe contaminant and use of secondary.
Of the 15 severe, 12 used secondaries and 3 used none. You might say that use of a secondary is the cause of contamination. Bucket vs. glass fermenters doesn't seem to matter.
So, that's severe... how about if we break it into two samples; clean vs ANY contamination.
25 out of 35 were contaminated in some way.
Of those, 10 used O2 and 15 used "other". Only ONE used an air pump.
6 out of 25 contaminated did NOT secondary. 19 used a secondary. Again, that's the higher positive correlation.
Of the 9 completely clean samples, 7 used glass primaries and NONE of them used buckets for both primary and secondary.
Anyway, interesting data but meh... Not many other conclusions can be drawn. You certainly have to discard anything having to do with attenuation as it relates to oxygenation method because the wort is derived from completely different mash profiles and fermented at different temps with different yeast pools.
Does Pedio reproduce using oxygen like yeast does?
I'm not 100% sure Bobby but I think Lactic acid bacteria (which includes Pedio and Lacto) ferment sugars and create lactic acid...so it doesn't appear that they use oxygen like yeast does during the growth/lag phase (yeast use O2 during the growth phase but not during fermentation; as opposed to acetic acid bacteria that do not ferment but rather respire by oxidizing ethanol to acetic acid). I did notice that most of those infections were Pedio so that does seem to invalidate the hypothesis that the O2 is 'helping' the bacteria too much.
I agree you can't really draw any conclusions from that study...small sample size and too many variables. The most surprising thing to me was the number of infections relative to totally clean brews. I'm guessing that many 'mild' infections go completely unnoticed.
__________________ Early brewers were primarily women, mostly because it was deemed a woman's job. Mesopotamian men, of some 3,800 years ago, were obviously complete assclowns and had yet to realize the pleasure of brewing beer.- Beer Advocate
The optimum level of dissolved oxygen content depends on the type of beer style that you are brewing, as it is one of the key factors in determing the amount of yeast byproducts produced (along with the other key factors of pitch rate and temperature). I am really surprised that more homebrewers do not own a dissolved oxygen meter. You can get them for about $175 and you are going to pay that much for many other standard pieces of brewing equipment.
The only way to control your dissolved oxygen levels is with oxygen and a DO meter. Aerating the wort can only generate a maximum of 8ppm dissolved oxygen, which is insufficient for certain styles. WIth a DO meter and an oxygenation system (as opposed to an aeration system), you can vary the amount of DO between 4pmm and 26ppm, according to the effect that you are trying to achieve.
Ok, so there's already a half bazillion home brewers who aren't convinced that a $50 oxygen reg/stone kit is worth the money and you want people to add another $175 piece of gear? Heck, I have oxygen and wouldn't spend on a DO meter.
Ok, so there's already a half bazillion home brewers who aren't convinced that a $50 oxygen reg/stone kit is worth the money and you want people to add another $175 piece of gear? Heck, I have oxygen and wouldn't spend on a DO meter.
Yeah, that's a good point. There are a lot of brewers who are not really concerned about maximizing every aspect of their process, and so even a $50 investment would be seen as a large one. But what is interesting is that there are plenty of serious all-grain brewers who spend thousands of dollars on their systems, and then don't try to control DO levels. They would easily spend several hundred dollars to set up a very precisely temperature controlled mash with gas solenoid valves, Love TS controllers, etc., in order to maintain mash temps within 1 degree, but then neglect to attempt to control oxygenation levels. But I can understand the desire to keep certain variables in your system static. Some people might want to try to generate the same effects of low or high oxygenation by instead altering pitching rate and temperature. Temperature is easily controlled. However it is easier to precisely measure DO than pitching rate, since yeast cells are not easily counted and the estimates generated from pitching calculators are just estimates.
A DO meter is fairly high on my wish list. Certainly before any brewhouse upgrades.
I agree with the point that you cannot over-oxygenate with air and that’s what I see as a big benefit. Many (large) commercial breweries use air to get O2 into the wort. It’s cheaper than O2 and if the wort is cold enough the saturation level is closer to 12 ppm than 8.
Yes, you cannot draw a connection between pure O2 and contamination from this study. pure O2 is pretty much self sterilizing in the bottle. Any bacteria would simply oxidize to death. I use pure O2 and my beers are free of infections. The reason why I prefer O2 over air is that it makes less foam. But I don’t know how much O2 I actually get into the wort.
Don't get me wrong. I'd love to have a DO meter and I might be convinced to buy a used one for $50 if it ever came around. Then again, to your point about overspending on everything, I'm a cheap ass with a fully manual brew rig that I welded myself. I would buy a DO meter before a conical.
Edit; after a little reflection, I think a decent solution is to borrow a DO meter and buy a used medical O2 regulator. After a little testing, you can arrive at a typical DO level given a certain gravity, flow rate, and time. My medical reg goes as low as .25 lpm which is what I use for 60 seconds. If I know that it always gets me to like 12 ppm, I'd call it a day and give the DO meter back. I've stopped myself from building a inline oxygenator due to the fact that even though my o2 flow rate is fixed, my chiller flow isn't.
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