Author: Will Lovell
In addition to sanitation, yeast pitch rate, and fermentation temperature control, a factor most brewers view as being essential to producing good beer is preventing oxidation. While this often involves mechanical measures such as pressurized fermentation and closed transfers, many rely on chemical means of oxygen mitigation including the use of ascorbic acid, an antioxidant used widely in the food & beverage industry to prolong shelf-life.
Typically, chemical antioxidants like sodium/potassium metabisulfite are added post-fermentation, at which point any oxygen introduced during packaging is ostensibly neutralized. However, a growing number of brewers claim that adding ascorbic acid to the mash has superior results, serving as a prophylactic to future oxygen exposure by reducing reactive oxygen species present in grain.
Based on the non-significant results of a past xBmt looking at the impact of adding ascorbic acid at packaging, I was prepared to write it off altogether. However, I soon learned that people were adding it during the mash and performed another xBmt on Hazy IPA, which is notoriously sensitive to oxygen, that returned significant results. Curious what effect this unique antioxidant might have s when added to the mash of a more delicate German Pils, I designed an xBmt to test it out.
| PURPOSE |
To evaluate the differences between a German Pils where ascorbic acid was added to the mash and one that was not dosed with ascorbic acid.
| METHODS |
For this xBmt, I went with a simple German Pils recipe with the hope any differences caused by the variable would be readily apparently.
Pils For Days
Recipe Details
| Batch Size | Boil Time | IBU | SRM | Est. OG | Est. FG | ABV |
|---|---|---|---|---|---|---|
| 5.5 gal | 60 min | 31.2 | 4.2 SRM | 1.048 | 1.01 | 4.99 % |
| Actuals | 1.048 | 1.01 | 4.99 % | |||
Fermentables
| Name | Amount | % |
|---|---|---|
| Floor-Malted Bohemian Pilsner Malt | 11 lbs | 97.24 |
| Victory Malt | 5 oz | 2.76 |
Hops
| Name | Amount | Time | Use | Form | Alpha % |
|---|---|---|---|---|---|
| Tettnanger | 30 g | 60 min | Boil | Pellet | 2.4 |
| Magnum | 11 g | 60 min | Boil | Pellet | 16.5 |
| Tettnanger | 45 g | 5 min | Boil | Pellet | 2.4 |
Yeast
| Name | Lab | Attenuation | Temperature |
|---|---|---|---|
| Harvest (L17) | Imperial Yeast | 74% | 50°F - 60.1°F |
Notes
| Water Profile: Ca 87 | Mg 14 | Na 0 | SO4 149 | Cl 83 |
Download
| Download this recipe's BeerXML file |
After adding identical volumes of RO water to separate Delta Brewing Systems AIO units and setting the controllers to heat them up, I weighed out and milled the grains.
Once the water for each batch was adequately heated, I incorporated the grains then immediately added ascorbic acid to one mash.
Both controllers were set to maintain my desired mash temperature of 152°F/67°C.
While the mashes were resting, I prepared the kettle hop additions.
Once each 60 minute mash was complete, I removed the grains then boiled the worts for 60 minutes, adding hops at the times listed in the recipe.
When the boils were complete, the worts were quickly chilled before I took refractometer readings showing a slight difference in OG.
Identical volumes of wort from either batch were transferred to separate FermTanks that were placed in my chamber and left to finish chilling to my desired fermentation temperature of 64°F/18°C, at which point I pitched a pouch of Imperial Yeast L17 Harvest into each.
With signs of activity absent after 2 weeks of fermentation, I took hydrometer measurements indicating the beers had similar levels of attenuation.
At this point, I pressure-transferred the beers to CO2 purged kegs that were placed in my keezer and left on gas for 6 weeks before they were ready for evaluation.
| RESULTS |
A total of 20 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of the beer where ascorbic acid was added to the mash and 2 samples of the beer that was not treated with ascorbic acid in different colored opaque cups then asked to identify the unique sample. While 11 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, only 10 did (p=0.092), indicating participants in this xBmt were unable to reliably distinguish a German Pils where ascorbic acid was added to the mash from one that was not treated with ascorbic acid.
My Impressions: Out of the 5 semi-blind triangle tests I attempted, I correctly identified the odd-beer-out 3 times, and those were admittedly lucky guesses, as these beers tasted the same to me – bready malt backbone with moderate bitterness and a nice noble hop character, all presented in a crisp and highly drinkable package. Great examples of German Pils!
| DISCUSSION |
Brewers of quality beers are very well aware of the negative impact of oxygen exposure and hence employ various methods to reduce the risk of oxidation. Of the myriad chemical antioxidants available, ascorbic acid is one of the few that’s believed to be most effective when added to the mash rather than to the fermented beer at packaging. Countering this claim, tasters in this xBmt were unable to reliably distinguish a German Pils where ascorbic acid was added to the mash from one that was not treated with ascorbic acid.
Viewed in light of findings from a prior xBmt on the same variable that was focused on Hazy IPA, one potential explanation for the present result is that German Pils isn’t as sensitive to oxygen exposure. It’s also possible the 8 weeks the beers were allowed to rest prior to data collection wasn’t enough for the negative impact of oxidation to set in, though this seems less likely considering prior evidence demonstrating the rapidity with which oxidation takes effect.
I’ve honed my brewing approach to minimize as much exposure to oxygen as possible, and this is largely through mechanical means. However, I certainly see the value in employing the use of chemical antioxidants in certain situations, particularly when making styles known to be more sensitive to oxygen. Given how well metabisulfite works at mitigating oxidation when added post-fermentation, I’m wont to stick with it, though perhaps combining that with a dose of ascorbic acid in the mash will provide further assurances.
If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!
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16 thoughts on “exBEERiment | Impact Adding Ascorbic Acid To The Mash Has On A German Pils”
How much Ascorbic acid did you use?
5 grams
How much ascorbic acid was added to the mash?
5 grams
Your beer never hits oxygen since it’s transferred to CO2-purged kegs—super effective for keeping oxidation at bay. Ever thought about trying it with unpurged kegs and just purging the headspace at the top?
I was just repeating the same steps I did for a previous experiment, that involved hazy IPA and came back significant. The main difference in this experiment is I waited 8 weeks to ‘lager’ the Pils. I intentionally did a less hoppy style this time, just to see if we could replicate the results of the previous. Maybe those nobles hops are just less susceptible to oxidation, but I might repeat the xBmt again and do it in a more traditional double IPA or less traditional West Coast Pils to see what happens.
https://brulosophy.com/2024/10/07/exbeeriment-impact-ascorbic-acid-in-the-mash-has-on-a-hazy-ipa/
Kinda nonsense since you add 100% oxygen to the wort prefermentation.
Hi Will, thank you for the article! How do you add the metabisulfite when you pressure transfer? Cheers, Immo
feel free to shoot me an email and we can discuss a few methods. First Name @ brulosophy.com
I have to wonder, If adding the Ascorbic Acid to the mash and it having NO apparent effect on the taste of the finished beer, Wouldn’t it make sense to add it as a preventive measure?
It is really cheap and seemed to make a difference in this xBmt, so yeah, why not? https://brulosophy.com/2024/10/07/exbeeriment-impact-ascorbic-acid-in-the-mash-has-on-a-hazy-ipa/
Given you have methods and equipment to vastly reduce the oxygen exposure even without chemical additions, I can see why it didn’t make that big of a difference.
I’d be curious to find out what the difference would be for someone with generic equipment and methods that inevitably will expose it to a good amount of oxygen, like a plastic bucket fermenter and bottle conditioning
The main goal here was to repeat the xBmt in basically the same way I did for this one that came back significant in a Hazy IPA. https://brulosophy.com/2024/10/07/exbeeriment-impact-ascorbic-acid-in-the-mash-has-on-a-hazy-ipa/
Ascorbic acid in the mash is cheap insurance, but its no panacea. I think if you expose it to O2 all along the way, then you’ll likely just end up with oxidized beer.
I can sort-of answer that, as that’s what finally tipped me into keg packaging.
Up until then I was fermenting in a plastic bucket (albeit one with a lid and a tap) and bottle conditioning. I had the usual problems with hazies spoiling due to oxidation. I brewed a citrus IPA (with tangelo zest added to the boil) and added ascorbic acid too. It still oxidised, before the bottle carbonation was complete!
So now I ferment in a Fermzilla and pressure transfer/closed circuit siphon into purged kegs.
Sorry, but this is yet another experiment where the methodology isn’t appropriate for determining the effectiveness of what’s being tested.
The only way for this test to be valid would be to actually expose the beer to some amount of oxygen on the cold-side, approximating what a typical homebrewer would, and then evaluate the results with and without ascorbic acid.
I’m not saying that you have to massively expose the beer to oxygen, but the fact that you pressure-transferred into purged kegs **negates** the whole thing.
Side note: you didn’t specify how you purged the kegs; if you properly purged by filling completely with liquid and then pushing it out with CO2 then there is virtually zero O2 present, and if the oft-repeated claims that simply putting an empty keg on gas and pulling the release valve a bunch of times actually works (IMO it doesn’t) then that would also negate the test.
Copy and Paste from above: I was just repeating the same steps I did for a previous experiment, that involved hazy IPA and came back significant. The main difference in this experiment is I waited 8 weeks to ‘lager’ the Pils. I intentionally did a less hoppy style this time, just to see if we could replicate the results of the previous. Maybe those nobles hops are just less susceptible to oxidation, but I might repeat the xBmt again and do it in a more traditional double IPA or less traditional West Coast Pils to see what happens.
https://brulosophy.com/2024/10/07/exbeeriment-impact-ascorbic-acid-in-the-mash-has-on-a-hazy-ipa/