Author: Will Lovell
Cold-side oxidation is the bane of a brewer’s existence, particularly when it comes to highly hopped styles, as they’re known to be more sensitive to oxygen than others. The primary symptoms of oxidation include muted hop character, the presence of an oddly unpleasant (by most standards) sweetness, and a darkening of the beer’s color.
With the rise in popularity of non-alcoholic options, some brewers have started making hop water using methods pulled from brewing including adding potassium metabisulfite (KMS) to scrub any dissolved oxygen from the water. Similar to beer, the volatile hop oils in hop water are susceptible to staling when exposed to the oxygen that’s present in plain water, and hence the use of KMS is believed to reduce this risk.
I typically always have a keg of hop water on tap, as it offers a refreshingly hoppy zing during times where alcohol just isn’t in the cards. One thing I abhor is the flavor of oxidized hops, which is why I use several mechanical methods for reducing cold-side oxidation when brewing beer, though for hop water, dosing with a small amount of KMS is easier and more efficient. Curious of the impact this has, I designed an xBmt to test it out.
| PURPOSE |
To evaluate the differences between a hop water dosed with KMS and one that was not dosed with KMS.
| METHODS |
For this batch, I went with an even blend of two of my favorite classic American hops, my goal being to emphasize the citrus characteristics.
Cascadian Clear
5 gallons/19 liters distilled water
3 g gypsum
56 g Cascade
56 g Amarillo
After running to the grocery store to buy 10 gallons/38 liters of spring water, I poured 5 gallons/19 liters each into separate kegs that were not first purged with CO2.
I then weighed out and added gypsum to each batch.
I also prepared the hop additions.
Next, I weighed out and added KMS to one batch while the other was left untreated.
Finally, I added an identical amount of hops to each keg.
The sealed kegs were left in my 40°F/4°C for 72 hours before I pressure-transferred the hop waters to CO2 purged serving kegs that were placed on gas in my keezer. After a week of conditioning, they were carbonated and ready to serve to tasters.
| RESULTS |
A total of 20 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the hop water that was not treated with KMS and 1 sample of the hop water that was treated with KMS 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 achieve statistical significance, only 7 did (p=0.52), indicating participants in this xBmt were unable to reliably distinguish a hop water that was not treated with KMS from one that was treated with KMS.
My Impressions: Out of the 5 semi-blind triangle tests I attempted, I correctly identified the unique sample just twice, and those were admittedly lucky guesses. To my palate, these hop waters were identical in every way, which was a good things, as they were refreshingly delicious!
| DISCUSSION |
Hop water is an excellent option for beer lovers who want to satiate their hoppy desires without consuming alcohol. Given what’s known about the interaction of hops and oxygen, namely that it seems to expedite the staling process, some makers of hop water and begun dosing their water with KMS as a means of scrubbing any dissolved oxygen and thus extending the shelf-life. Interestingly, tasters in this xBmt were unable to reliably distinguish a hop water that was not treated with KMS from one that was treated with KMS.
Based on the data collected, we’re unable to determine actual levels of oxidation, or lack thereof, in either batch of hop water, just that the addition of KMS didn’t seem to have much of an impact in this particular scenario. It’s possible that neither batch of water had enough oxygen present to have a deleterious effect, or perhaps it would have progressively worsened, though I didn’t notice any changes in either hop water in the few weeks they were on tap.
Despite this non-significant result, considering how much I loathe oxidation as well as how cheap and easy-to-use KMS is, I’ll continue dosing my hop water with it. Even if it has zero impact on oxidation, KMS is an effective way to neutralize any chlorine present in water, so I’d highly recommend it for anyone making hop water with tap water.
If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!
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10 thoughts on “exBEERiment | Impact Potassium Metabisulfite Has On Hop Water”
A side question; Is there any risk for botulism with hop water as it is not acidified? Would KMBS reduce that risk if there is a risk?
Add citric acid to get between 3.8 and 4.0 ph (my preferred sweet spot) to fight any microbial issues. Adds a little bite and brightens up the hops.
The risk isn’t zero. It never is, for anything. But it’s very low. Vastly less carbon and other critical elements in hop water compared to NA beer.
I have a couple questions about your hop water process. Some people add some kind of lemon juice, or something for acidity I think. You don’t do that kind of thing? When you add the hops in the keg, are they just loose in there? And then when you transfer to another keg, do you filter them out somehow? I wonder if that gets a better flavor/aroma than if one was to use a hop bag. I made a hop water once years ago but never went back to it. Your post is making me think about trying it again. Cheers.
I have a couple questions about your hop water process. Some people add some kind of lemon juice, or something for acidity I think. You don’t do that kind of thing? When you add the hops in the keg, are they just loose in there? And then when you transfer to another keg, do you filter them out somehow? I wonder if that gets a better flavor/aroma than if one was to use a bag. I made a hop water once years ago but never went back to it. Your post is making me think about trying it again. Cheers.
I’ve never made hop water but inclined to give it a try since I usually have a an open tap on my keezer. Had a couple questions on your process, in the ingredient list you say distilled water but then mention picking up some spring water. Which do you use? Also, you say you held the kegs at 40°F for 72 hours before transferring, do you really dry hop it that cold?
I have a couple questions about your hop water process. Some people add some kind of lemon juice, or something for acidity I think. You don’t do that kind of thing? When you add the hops in the keg, are they just loose in there? And then when you transfer to another keg, do you filter them out somehow? I wonder if that gets a better flavor/aroma than if one was to use a bag. I made a hop water once years ago but never went back to it. Your post is making me think about trying it again. Cheers.
I am intrigued to make a hop water as I usually have a free tap in my keezer and also like to get a hoppy kick at times where I don’t want to have a beer. I had a couple questions on your process, you mention in the ingredients list using distilled water but then in the process you say you picked up spring water. Any preference on one over the other? I typically brew with RO water and adjust it based on the beer style.
Also, you list that you dry hopped at 40°F for 72 hours, is that correct? Any reason to dry hop at that low of a temperature?
Looking forward to giving this a try!
If water is kept cold then Clostridium botulinum can only work very slowly
All my hop waters taste very green, and don’t reflect the taste of specific hops particularly well. When I ask folks at Haas about this, they reply with “since there’s no alcohol present to act as a solvent for terpenes, you can’t expect hop water to taste like a specific hop”. Seems I need a different approach to making better tasting hop waters. (Fruit extracts, Abstrax products, etc…) Your inputs are appreciated.