Using the regular amount of yeast/sugar, 7 ppm DO is reduced to 1.31 ppm in 24 minutes. Then heating from 30C to 72C will eliminate all oxygen, given the process is linear. If the yeast method creates some off-flavors, it should be measured what will be the gain if the amount of yeast/sugar is decreased. Also, what would be the additional DO-reduction by the yeast while it is still active during the heating. There’s some additional information from Bilsch here: Alternate methods for oxygen scavenging mash water - Page 4 - German Brewing
“Increase water temp to 44c and transfer with underletting to the grain. Was 40/60 pils/wheat (+6.5% C125) grain bill. The idea here being to dough in at a temperature where yeast would still be active, let it do it’s O thing… then ramp up to beta and alpha.
DO at transfer was 0.29 mg/l”
The other idea I had was: since I buy water in 5L jerrycans, I might add yeast/sugar to one or more of them the night before I brew, and add that deoxygenated water cold to the mash tun after having heated the water to 70-80C. Because I also do not like having to use the wort chiller at this stage of the brewing process. Complicates things for me…
I would think that the transfer from the jerrycans to the tun would be an additional point of pickup that you could avoid. Could you put the water in the tun the night before and leave that overnight? I’m assuming you have a heated mashtun in this scenario.
I’m going to be doing some trials where I brew with only heating to strike temp, 185 °F (85 °C) and full preboil.
I’ll be interested to see if the impacts of increased Sulfate levels from my larger doses affect the final beer. Early results coming in from people have shown that higher sulfite loads give some undesirable characteristics. So far I have only preboiled but I’m looking to give some data points here.
As Martin said above, you should make sure your “house is in order” (mash cap, limit by all other means, etc) before playing with dosing and I agree. That’s part of the reason I put the disclaimer in the blog post. Yet if I can streamline my day at all and not affect final quality, I’ll try that out as well.
I have a very limited understanding of this low oxygen brewing. I’m also lazy. So I’m considering which aspects of it would give me the biggest bang for my effort. I currently use Brewtan B. I am also quite scrupulous with exposure to oxygen post fermentation. But given that this thread is on pre-boiling mash water, how much of that oxygen is left in the wort after the 60 minute boil? And whatever is left, isn’t that scavenged by the yeast during fermentation?
I recognize that these questions may have been asked before but I just don’t want to put forth effort and potential cost for something that is a not discernible in the final product. So to re-state, I don’t question the underlying principles involved in low dissolved oxygen brewing. I just want to know where the tipping point is for what makes a discernible difference in the beer. Please don’t hear this that I’m criticizing or flaming anyone or any other perspective, I am just looking for where I choose to settle in this area of science.
One of the main points is that there exists a flavor component in malt that when exposed to Oxygen is volatilized very rapidly. One thing you’ll notice if you limit Oxygen is the suppression of mash smells in the brewery.
A dissolved oxygen level on the order of 1 ppm throughout the entire hot side is enough to render the process moot.
So there are a few points to think about here:
1.) Pre-boiling totally eliminates Oxygen from the mash water. It gives the most margin.
2.) Whether you pre-boil or not, you need active scavengers (metabisulfite) to combat the Oxygen levels brought on by:
a.) O2 solubility at mash temps (4-5 ppm)
b.) Mash-in ingress (1-3 ppm)
c.) Atmospheric diffusion (1-2 ppm/hr)
3.) Capping your mash can mitigate much of c.)
4.) Carefully doughing-in can limit b.)
5.) You CAN get by if you make all other improvements to your process (capping, limiting through mechanical means, tightening hose connections and fittings, etc.) but it comes at the expense, as some have mentioned, of increasing your Sulfate content.
Thanks BM for the quick summary, I’ve been looking through a lot of material and thinking about trying find things out. I think this was really helpful in evaluating the impact. How quickly does the volitizaton occur, and how does temperature impact this? I’ve always kind of wondered how chilling and introducing O2 for yeast use impacts these chemicals. I know I’ve heard from Jamil that yeast will scavenge oxygen almost immediately during fermentation, but I’ve never been sure.
This is the reason that I believe many brewers that have attempted low-oxygen brewing, see no improvement. If your processes and methods are not effective enough to avoid too much oxygen contact at ANY point in the process…the entire result is compromised. You just negated any opportunity to produce a low-oxygen result. For many brewers, that is too steep a penalty and they rightfully and accurately report that the goal is not achieved.
I’m continuing on my quest for low-oxygen results and I believe that my beers have improved. The most important point I’m trying to convey, is that a failure in oxygen control at any point in the process means that no improvements will be achieved. Understanding all the sources for oxygen contact have to be taken for the brewer to make the incremental process improvements that can improve beer.
Question for you low oxygen brewers. Are you actually taking dissolved oxygen measurements during the brewing process, or are these numbers just ones reported in the brewing literature?
Followup: If you are on a well and brewing with well water, could you not skip the pre-boil since ground water has zero dissolved oxygen? Or does the strike water dissolve oxygen at a faster rate than heating it to pitch temperatures?
On of the stated benefits is hops flavors and aromas staying prominent longer. The hops generally don’t get added until the boil. So, hopefully you still get that benefit even if the mash got too much oxygen.
I think what Derek is trying to get across is that once a specific amount of dissolved oxygen enters the mash, that the delicate polyphenols of the malt become quickly oxidized and can result in a loss of malt aroma/flavor.
And this can all occur before the boil even happens.
Yeah, after my pre-boil, it literally takes less than 5 minutes to get down to about 165F or so (for dough in). So fast, that if you are not ready, one could easily miss the temps if not paying attention.