Low Oxygen Brewing

I would add that there's more than one type of "active." Yeast that have been given a small amount of "wakeup" yeast are just eating (and pretty much not propagating). Yeast in a true starter wort are propagating, which is what you want them to do (at first) in the main wort.

 

Depends when you pitch. If your yeast are actively fermenting they aren't replicating any more or at least not like they were in the log phase.

 

Oh here's another question, apologies if it's been covered elsewhere. Once fermentation is slowing down, is it better to switch to a dry airlock (like one of these)? My reasoning is that a "wet" airlock will allow some amount of oxygen to diffuse into the headspace, but the amount may be so trivial that it's better just to keep the "wet" airlock in place rather than switching airlocks (which inevitably involves allowing some oxygen into the fermenter).

 

I've looked at the silicone dry airlock. I'm not sure how it really works (assuming it does). But this kind of question/dilemma is the reason I like spunding valves instead of any kind of traditional airlock.

 

So I was at Chico's Sierra Nevada the other day on tour and took a pic of this brew log sheet on a brite by their small batch bottling line. Noticed this part pictured below, which shows the PPB (not PPM!) O2 levels... My question is, what is causing the O2 levels to reduce here as time goes on? Did they just add sugars/fresh yeast or something?

Beer was moved into the BBT on 2/23.

This was a gin barrel aged Tripel by the way, and excellent at that! (We were able to taste from the tank). I assume due to the barrel aging the DO was higher at the start... curious how the low O2 is maintained with barrel aging. Thoughts?

@TheBeerery ?

 

I would assume dissolved O2 was decreasing because some of the O2 was oxidizing something, and therefore no longer free O2. I think you'd expect to see the same thing with any beer that's just sitting in a (more or less) airtight environment.

 

Maybe a Sierra Nevada brewer will answer your question?

@SierraTerence

Cheers!

 

I'm not very familiar with the methodologies used in a big brewery, but I tend to doubt that Sierra Nevada would tolerate the amount of oxidation that would be required to reduce O2 from 538 ppb to 55.9 ppb. The solubility of oxygen in water (and, I assume, beer) is a function of the partial pressure of oxygen in the atmosphere over the fluid. If the gas above the beer in the bright tank is mostly CO2, then oxygen could come out of solution. This would also explain the increasing levels of CO2 in the beer, since the same partial pressure consideration applies.

I admit I'm just guessing here.

 

Following up after checking my math... based on this blog post, if Sierra Nevada has CO2 with a 10 ppm oxygen impurity (that is, 0.001% oxygen), then at 2 volumes of CO2, the beer should hold about 28 ppb oxygen. (You can get this number from the chart about halfway down the blog post, under the heading "How Much is TOO Much?")

Now as you can see from the Sierra Nevada log, it's actually got more than 2 volumes of CO2, so we would expect slightly more than 28 ppb dissolved oxygen. Also, who knows how pure their CO2 is. But the point is that a brewery like Sierra Nevada should be able to get dissolved oxygen measured in ppb down to the double digits, which would explain the progression of dissolved oxygen that we see in the log. Of course, getting O2 out of solution doesn't reverse any damage that it has already done, and surely some of the O2 isn't leaving solution but rather is reacting with organic material in the beer. So I don't want to exaggerate the point, but I think a lot of the drop in dissolved oxygen is attributable to oxygen's low solubility in the conditions in which Sierra Nevada is storing the beer.

 

The natural antioxidants in the beer are consuming the o2, which in turn is staling the beer. That and/or they are doing co2 sparging.

FWIW

With my methods and practices I am right around 20ppb in the can, and sub 10 in the keg.

 

@minderbender Has covered it for the most part. With barrel-aged beers we do the best we can with O2 pick up but you will always get a good amount no matter how careful you are. We will back pitch fresh yeast when transferring from barrels to our tanks for packaging. In addition, tanks are purged with CO2 prior to transfer. Reduction of O2 levels over time will happen by the yeast picking it up, some coming out of solution and the remain is reacting with the beer causing oxidation.

 

Yeast and its ability to scavenge oxygen is a wonderful thing!

Cheers!

 

Until they go dormant.

 

@JackHorzempa did you get a response from Charlie?

 

Just now seeing this a few months later... When I was at Doemens I asked one of the teachers about HSA and specifically about how it impacts Pilseners. I believe I talked to Michael Zepf (Director of Education) and Thomas Huber who is the director for their lab. I was told that they had done a study where pure oxygen was added throughout the entire length of the mash, lauter, boil, and whirlpool and then it was aerated like normal during the wort transfer to the fermenter. They brewed a control batch and both batches were analyzed with tasting panel and gas chromatography (Maybe I'm wrong on the second point... maybe it was HPLC). They found no differences in flavor or shelf stability.

That said, some people will always swear by certain techniques and if it makes you feel comfortable to use them and it helps give you confidence in your brewing, then maybe it is worth the time and effort. I personally believe that very few homebrewers (or commercial for that matter) have the ability to control enough of the parameters that matter most for completely precise consistency to say that something as small of an issue as HSA is worth the effort to eliminate. It's worth pointing out that the big breweries that are doing low DO brewing have a LOT more control than any one of us on this forum.

 

Some would say if you are using barrier tubing on your draft system you are allowing far too much oxygen uptake. Stainless is the only solution if you really want to serve the best beer. But what with gaskets and washers, even there it's just unacceptable.
For some it's indisputable. A given fact even.

But you go ahead and believe what they teach at Doeman's. They probably aren't really cutting edge anyway.
Cheers.

 

Damn man... You sound salty. All I did was reference a scientific study that was conducted my German Master Brewers which seemed credible considering they are among the world's experts on the styles of beers that are claimed to benefit from low DO brewing. I even tried to say there is some credence to the people that choose to disregard scientific studies. Personally, I have things that I just won't do even though science says I'm wrong... For example, I will not open a hop bag until immediately before putting it into wort or beer. My assistant knows that I will not allow her to open a bag of hops more than a minute before the addition because of my concern of losing the most volatile aromas. It's a stupid thing that I carry with me, but it makes me feel good, which is ultimately the most important thing towards feeling comfortable with your brewing techniques.

 

I don't mean to discredit your statement. I agree 100% in fact. I am personally pretty overboard with the LO brewing crusaders though. Well, crusader.

I also know that brewing science is still young, especially when compared to traditions we have gained through centuries of trial and error, as well as communication. We should be looking at all areas that could benefit our brewing, and applying practical techniques when possible and typically enjoyable too. Homebrewing is different than profit brewing after all.

I am pretty salty when it comes to throwing around opinion masquerading as science for profit though.
Guilty.

 

A little more grain? Can you elaborate?