Author: Matt Del Fiacco

There appears to be growing acceptance among brewers that making water adjustments is an important aspect of crafting delicious beer, with the general approach seemingly shifting from a focus on matching historical profiles to determining the particular profile best suited to the style being made. Historical water profiles being less a function of choice and due more to availability, plus the fact some breweries from centuries ago were actually adjusting their brewing water, add to the futility of attempting to match a particular profile.

A common method among modern brewers involves starting with a “blank slate” then adding minerals to achieve one’s desired profile, often relying on reverse osmosis (RO) water, which Wikipedia explains is…

…a water purification technology that uses a semipermeable membrane to remove ions, molecules and larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property, that is driven by chemical potential differences of the solvent, a thermodynamic parameter.

Simply put– RO water is real clean, an ideal base from which to build on, though some believe it may not be the best option for use on its own. In addition to being nearly absent of flavor ions known to impact the character of beer, like sulfate and chloride, RO water is also lacking in minerals believed to be crucial for starch conversion, yeast health, and beer clarity.

With so many previous water chemistry xBmts returning significant results, I became interested in how a beer produced with super clean RO water not only would taste, but if it would effect other aspects of the brewing process. Having heard from others who reported success using unadulterated RO water for their beer, I decided to put it to the test!

| PURPOSE |

The evaluate the differences between a beers of the same recipe brewed with RO water that was either pure or adjusted to a particular mineral profile.

| METHODS |

Czech Pilsner is a style known for being brewed with a generally soft water profile, which contributes to a clean and balanced character I felt would be ideal for this particular xBmt.

Tabula Rasa

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5 gal 90 min 34.3 IBUs 4.8 SRM 1.057 1.021 4.8 % Actuals 1.057 1.015 5.5 % Fermentables Name Amount % Pilsner (Weyermann) 9.25 lbs 88.1 Carafoam (Weyermann) 9 oz 5.36 Carahell (Weyermann) 8 oz 4.76 Melanoidin (Weyermann) 3 oz 1.79 Hops Name Amount Time Use Form Alpha % Czech Saaz 7 g 60 min First Wort Pellet 3.5 Czech Saaz 15 g 60 min Boil Pellet 3.5 Czech Saaz 33 g 30 min Boil Pellet 3.5 Czech Saaz 69 g 10 min Boil Pellet 3.5 Yeast Name Lab Attenuation Temperature Harvest (L17) Imperial Yeast 72% 50°F - 60°F Notes Water Profile (adjusted batch only): Ca: 50 | Mg: 5 | Na: 0 | SO4: 60 | Cl: 60 Download Download this recipe's BeerXML file

I built a single large starter of Imperial Organics L17 Harvest a few days beforehand.

I woke up early a couple days later and turned on my elements to heat the water I’d prepared the night prior, both using the store-bought RO with one being adjusted to the profile indicated in the recipe.

While the water was heating, I weighed out the minerals I’d previously determined would get me to my desired profile using Bru’n Water Spreadsheet, then added them to one batch.

I then weighed out and milled two identical sets of grain.

Once strike temperature was reached, I mashed in before checking to ensure each batch was at the same initial temperature rest of 146°F/63°C.

Twenty minutes into each mash, I began raising the temperature to 160°F/71°C and stole some samples for pH measurement. I had adjusted both batches with a small amount of lactic acid in order to control for pH.

After an additional 40 minute rest, I removed the grains and began heating the worts. Both batches were boiled for 60 minutes with hops added as stated in the recipe.

When the boils were finished, I quickly chilled the wort by running it through my counterflow chiller directly into sanitized fermentation vessels.

Hydrometer measurements showed the batch made with pure RO water came in a couple SG points lower than the batch made with adjusted RO water.

The filled fermentors were placed in temperature controlled fermentation chambers where they were left to finish chilling.

Once stabilized at my desired 48°F/9°C fermentation temperature, I evenly split the yeast starter between each batch. The following morning, both beers were bubbling away. After 8 days of cool fermentation, I racked the beers to kegs, onto which spunding valves were attached, then raised the temperature to 68°F/20°C for a few days.

After a few more days, I pulled samples to confirm FG was reached in both beers before reducing the temperature.

Curious to see how lack of minerals impacted clarity, I decided to forgo my usual gelatin fining process and let the beers lager in my kegerator for 2 weeks before serving them to participants!

| RESULTS |

A total of 22 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the beer made with unadulterated RO water and 1 sample of the beer made with adjusted RO water in different colored opaque cups then asked to identify the unique sample. At this sample size, 12 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, while a total of 14 (p=0.003) made the accurate selection. These results indicate participants in this xBmt were able to reliably distinguish a Czech Pilsner made with unadulterated RO water from one made with RO water built up to desired water profile.

The 14 participants who made the accurate selection on the triangle test were instructed to complete a brief preference survey comparing only the beers that were different. A total of 3 reported preferring the beer made with straight RO water, 7 liked the beer made with adjusted RO water more, 3 had no preference despite noticing a difference, and 1 person reported they perceived no difference between the beers.

My Impressions: I attempted 5 semi-blind triangle tests and was able to identify the odd beer out 4 times. To me, the beer adjusted to my desired water profile had what I can only describe as a more full flavor with a more expressive hop character in the aroma. While the straight RO beer was also really enjoyable, it seemed to be less characteristically clean as far as the style goes. In the end, I really enjoyed both of these beers, I just thought the minerals produced a more well defined flavor profile.



| DISCUSSION |

At the 2007 National Homebrewers Conference, John Palmer presented on an experiment he performed that demonstrated how different water profiles impact beer. Since April of 2015, we’ve published the results of numerous water chemistry xBmts that corroborate Palmer’s findings, and I’ve personally noticed improvements in my own beer that I believe is due to water adjustments. For these reasons, I didn’t necessarily find shocking the fact that participants in this xBmt could tell apart beers made with either straight RO water or RO water built to particular profile. These findings add to the growing evidence that adjusting brewing water with minerals has a qualitative impact on beer.

With RO water being essentially absent of all minerals, including those deemed to effect more than just beer flavor, I was curious to compare other more objective aspects of these xBmt beers. One area I expected to see a difference was in conversion efficiency, and while the adjusted water beer did have a slightly higher OG, it wasn’t by much, just a couple SG points. Since calcium is known to play a role in beer clarity, I also wondered if the adjusted RO water beer would drop clearer than the straight RO water beer, which didn’t seem to be the case.

All in all, these results leave me feeling even more confident that the mineral profile of the water we used to make beer matters. While I’ll absolutely continue to pay attention to my brewing water chemistry, I look forward to exploring the use of various profiles for particular styles, as given the subjective nature of preference, it’s possible what’s ideal for me may not be what I read somewhere else.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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