lodo w/SMB vs lodo w/AA

[Owenbräu]

Based on my brewtan b (BB) experiment, I confirmed for myself that simply attempting to prevent superoxides from forming is not adequate to protect against hot side oxidation (HSO). An active oxygen scavenger must be used on our scale and equipment. However, SMB can have negative side effects if the dose is too high, and, for me, it tastes out of place in ales. In fact, I don't believe ale strains are as efficient in managing sulfites as are lager strains. I can't back this in the literature, just my own experience. The next most commonly used antioxidant is ascorbic acid (AA), and there are even commercially available blends of SMB/AA that you can buy for brewing.

What intrigues me most about AA is that malt has a natural enzymatic system, ascorbic acid oxidase (AAO) and ascorbate peroxidase (AP) for utilizing AA to scavenge oxygen.

AAO Abstract.png (56.92 KiB) Viewed 9771 times

It would seem illogical to fail to take advantage of this built-in system, unless there were some negative side effects. In fact, there can be negative sides effects to using AA, mainly that the oxidized form of AA, dehydroascorbic acid (DHA), can in turn become an oxidizer itself. However, DHA generally has a very short half-life, and yeast also have the ability to convert DHA back to AA and use it for their own cellular metabolism. In theory, as long as you use AA upstream of fermentation, then the yeast should ensure that there are no AA or DHA remaining to negatively affect the finished beer. Studies have shown that AA is effective at preventing thiol, phenol and polyphenol oxidation during the mash. This is consistent with Tech's theory on phenols and their flavor contributions. Kunze speaks about the importance of specifically not oxidizing polyphenols during the mash and boil as well.

Reduced Thiols and Phenols.png (47.47 KiB) Viewed 9771 times

As a side note, citric acid (CA) is the most commonly used acid in lowering pH in sour beer production, and has its own antioxidant properties. Ironically, only one oxygen atom distinguishes citric acid from ascorbic acid. Both are readily available in fresh fruits to preserve and protect against oxygen degradation, and they are both likely present in sauergut. I need to investigate the composition of sauergut a little more, but based on the stability of the pH, redox potential and suite of microbes producing organic acids, it is very likely rich with oxygen scavenging organic acids. This blend of oxygen scavenging organic acids likely plays a significant role in sauerguts effectiveness in brewing, especially in combating HSO in the mash and boil.

I wanted to see if AA would be a direct substitute for SMB. I brewed up a third batch of helles (after the SMB and BB batches) to see if AA is a direct replacement for SMB. All other lodo practices were implemented, and the only variable was the the reagent. Both batches were brewed using:
1) pre-boiled strike and sparge water
2) underlet pumping for dough-in and subsequent transfer to BK
3) mash cap
4) copperless system
5) low boil (210-211F at the surface temp)
6) fast wort chilling
7) minimal time in the BK once chilled
8) yeast pitched during transfer from BK to fermenter.
9) cold fermentation (6C->9C>6C>3C)
10) same volume of stir-plate-propagated yeast from the same culture
11) grists and hops from the same lot of ingredients
12) MH and FWH
13) Spunding

Again, I wasn't interested to see if AA could mitigate HSO with hido brewing, but rather ask if AA is a direct substitute for SMB in a lodo process. In other words, are they equal in their effectiveness to scavenge oxygen and protect malt flavors, as well as what are the side effects downstream. I have the results of the brew days, as well as my own tasting notes. I will continue to take tasting notes along the way. A handful of folks I know whom are excellent performers in triangle tests will be given a repeated series of randomized tests once both beers are finished.

The Helles:
OG: 11.4 P
FG: 2.7 P
IBU: 15
EBC: 7

77% Best Pilsner
15% Best Vienna
5% Best Light Munich
3% Sauermalt
6 IBU Mittelfruh @ MH
6 IBU Perle @ FWH
3 IBU Mittlefruh @ SBH (15 min)
RO Water
3:1 Calcium chloride to calcium sulphate @ 50ppm Ca2+

AA - 75 mg/l in strike water, 10 mg/l in sparge water
SMB - 75 mg/l in strike water, 10 mg/l in sparge water

[Owenbräu]

All pictures are SMB left, AA right.

Right after doughing in:

Dough-In.jpg (470.91 KiB) Viewed 9769 times

End of the beta rest (20 minutes):

End of Beta.jpg (546.92 KiB) Viewed 9769 times

End of the alpha rest (40 minutes):

End of Alpha.jpg (541.73 KiB) Viewed 9769 times

[Owenbräu]

At mash out:

Mash Out.jpg (565.83 KiB) Viewed 9769 times

Samples after sparging:

Post Sparge .jpg (488.85 KiB) Viewed 9769 times

Samples after boiling:

Post Boil.jpg (199.69 KiB) Viewed 9769 times

[Owenbräu]

The pre- and post-boil samples for both SMB and AA:

Pre Post.jpg (598 KiB) Viewed 9764 times

Here are the mash samples I pulled for tasting.

Tasting Samples.jpg (643.36 KiB) Viewed 9764 times

I was on the fence over the course of the brew as to whether I could tell much difference between AA and SMB. Unfortunately, it was pretty overcast, so the lighting wasn't perfect for taking photos. But then I tasted the wort, and it was very clear to me that this was lodo. The malts were really fresh, bright and doughy, and I just stood there and drank the sample like it was hot-wort tea. It was absolutely delicious. There's a local place where I live that gives you warm croissants with a nutty honey butter drizzled in top before your meal, and that's immediately what I thought of when tasting the wort. Fresh and lingering warm pastries, dough and honey. Yum! One of my triangle tests guys came by at the end of the brew session, and he wasn't aware that I was testing AA. I handed him a sample of the post-boil wort after it was chilled. He said I don't know how you did it but this tastes like honey grahams and shredded wheat, then proceeded to drink the entire sample, lol.

I'm quote happy with the results of the AA test. I don't want to exclude SMB in my process (nor am I advocating than anyone else do either!), bc I tend to like functional redundancy when combating something as damaging as HSO. I do believe I will begin to experiment more with AA to minimize SMB in ales. Given the downstream benefits of using BB in controlling Fenton reactions, and having tested all 3 now, I am convinced the AA, BB and SMB is the trifecta in preventing oxidation and preserving flavors. I suspect that you can immediately cut the SMB dose in half when using AA alongside. I'm also intrigued about the role of organic acids (and other various compounds) in sauergut and their affect on HSO in brewing. I suspect that if you use CA and AA to initially reduce the pH in your sauergut, then you can pre-load it with antioxidants and increase its effectiveness. But, that's another experiment for another time.

Regardless, I will continue taking tasting samples and notes along the way, and hopefully get some triangle tests done. Amazing flavor in the wort is the first step, but the proof in the pudding comes from the finished beer.

[Bryan R]

The aforementioned commercial antioxidants. I have put it though it's paces.

[Owenbräu]

That's the one. Could you get them to tell you the ratio of SMB to AA?

[Natebriscoe]

Let me make sure I am following correctly, the comparison was one with no smb at all (replaced with AA) and the other just smb? Still got low o2 worts on both? How much effect does AA have on ph?

[Owenbräu]

I found that dose reduced my pH by about 0.2

[lupulus]

Thanks for doing this work. Extremely interesting! Quick question: Did you think about the stoichiometry of SMB vs AA? Most likely yes and if yes, why did you decide to go with even absolute weights (ie, 75mg/L of each) vs equalizing by molarity?

[Owenbräu]

Thanks. AA can scavenge from 1 to 3 parts O, depending on pH, sugar and ion concentrations (it can even regenerate itself), enzymes present, etc. It's chemistry is quite complicated and I'm by no means an expert on it. Bamforth used 1 g/l in his testing, and I found the same visual differences in the mini-mash testing using 100 mg/L. By absolute weight, neither SMB nor AA are limiting on my system at that concentration, so I wasn't concerned about molarity equivalence. At the same time, we want to minimize the "stuff" we are putting in our beer, so a true direct substitution was of interest to me.

I'm just trying to get a little mileage out of my brew days and share it with folks, but you're right, I would probably do some things differently if I had to go through peer review