Author: Ray Found

In all grain brewing, the importance of mash temperature is discussed ad infinitum, though it’s little sibling, responsible for finishing up the job of the mash, is largely neglected. The sparge is an integral part of the lautering process that involves rinsing the grain of residual sugar once the mash is complete. While some newer homebrew methods forgo this process, such as Brew In A Bag, many continue to sparge in order to achieve intended levels of sugar extraction, aiming for the commonly accepted grainbed temperature of approximately 170°F/77°C said to halt enzymatic activity and improve lautering by reducing wort viscosity. Indeed, conversations about sparge temperature tend to focus mostly on the negative effects of sparging too warm, namely the extraction of astringency causing tannins, yet relatively little exists about the impact of sparging with cool water.

Back in 2009, Kai Troester published an article on his cold-sparge experiment where he found sparge water temperature to have no apparent impact on overall efficiency or fermentability. Inspired by these findings, American Sour Beers author and blogger at The Mad Fermentationist, Michael Tonsmeire integrated the use of cool water in what he refers to as his “Minimal Sparge Process,” which he has reported satisfactory results with.

My interest in this topic stems largely from comments regarding the recent xBmt comparing the batch sparge method to fly sparge. A few brazen, rule-bucking brewers informed me they started sparging with unheated water in order to ease and streamline their brewing process, reporting no noticeable negative effects. As skeptical as I am, their rationale seemed sound– the enzymes had already done what they needed to do during the mash, conversion was complete, and there’s no good evidence suggesting 170°F/77°C dissolves and rinses sugar substantially better than room temperature water.

I’ve personally never paid much attention to the temperature of my sparge water and have always been most concerned with keeping it below 180°F/82°C in order to avoid the dreaded extraction of tannin. I’d never even considered sparging with unheated water, until now, that is.

| PURPOSE |

To evaluate the differences between two beers of the same recipe where one was sparged with cool water and the other standard sparge temperature water.

| METHODS |

I love American Amber Ale and it was time to get one on tap, so I designed a new recipe I thought would produce what is I appreciate most about the style.

Make America Amber Again

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 78.8 IBUs 15.7 SRM 1.053 1.007 6.1 % Actuals 1.053 1.01 5.6 % Fermentables Name Amount % ESB Pale Malt (Gambrinus) 8.124 lbs 65 Munich Light 10L (Gambrinus) 2.5 lbs 20 Caramel/Crystal Malt - 40L 1 lbs 8 Caramel/Crystal Malt - 20L 8 oz 4 Pale Chocolate Malt 6 oz 3 Hops Name Amount Time Use Form Alpha % Magnum 10 g 60 min Boil Pellet 12.1 Cascade 60 g 15 min Boil Pellet 9.3 Amarillo 40 g 15 min Boil Pellet 7.7 Centennial 20 g 15 min Boil Pellet 11.1 Yeast Name Lab Attenuation Temperature San Diego Super Yeast (WLP090) White Labs 80% 65°F - 68°F

After dosing my water with calculated amounts of CaCl- and gypsum, I set to the task of measuring out and milling two identical batches of grain.

I staggered the start of each batch by about 15 minutes to make things less complicated, but the process for each was exactly the same. It’s because of this precision my failure to hit my target 149°F/65°C mash temperature was consistent between the batches.

During the mash rest, I prepared the sparge water, a very simple task for the cold sparge batch that involved measuring it out in a graduated bucket and adding the required minerals. The standard sparge batch would prove only slightly more difficult, requiring a few minutes on my powerful burner. My groundwater was running at a balmy 75°F/24°C on this day and I heated the standard sparge water to 172°F/78°C for a difference of 97°F/54°C!

For both batches, I performed a brief vorlauf at the conclusion of the mash then collected the first runnings before adding the sparge water per my usual batch sparge routine. I measured temperatures at this point and found the standard temperature grainbed to be just over 155°F/68°C, while the cold water had dropped that grainbed to 93°F/34°C.

For whatever reason, I ended up with a little more wort from the cool sparge batch, less than a quart altogether, and I’m not certain why. It’s possible this difference in volume explains the discrepancy in pre-boil hydrometer measurements, which revealed the cold sparge batch to be slightly lower than the the hot sparge wort.

An often overlooked aspect of an xBmt brew day, I used the time during the boil to do some clean up, returning gadgets to their spots in my cart and giving my mash tuns a good wipe down.

After both batches completed their 1 hour boils, I quickly chilled the worts and again notice a small difference in volume. Hydrometer measurements at this point showed the SG gap had closed a bit, and volumes in the kettle had equalized.

Separate 6 gallon PET carboys were filled with equal amounts of wort from either batch and placed in my chamber to finish chilling to my target fermentation temperature. Having been travelling for work the day prior to brewing, I was unable to make a yeast starter and opted to use Safale US-05. I knew I didn’t have any at home, so I stopped into a great shop in Spokane, WA called Jim’s Home Brew on my way to the airport and bought 4 packs.

Once the worts reached the proper temperature, I pitched a rehydrated pack of yeast into each then it was off to another week long work trip. Hydrometer measurments taken when I returned 11 days later showed both beers had dropped to the same 1.010 FG.

I proceeded to cold crash and fine with gelatin. Five days later, it was time to keg.

After only 20 hours at 40 psi in my cool keezer, the beers we nicely carbonated, almost perfectly clear, and quite tasty!

| RESULTS |

All in all, 17 people participated in this xBmt including beer loving friends, homebrewers, and a couple podcast hosts. Each taster was blindly served 2 samples of the standard sparge beer and 1 sample of the cool sparge beer then asked to select the unique sample. In order to reach statistical significance with this sample size, at least 10 participants (p<0.05) would have had to made the accurate selection, yet only 7 (p=0.33) were able to do so. While we don’t usually report individual performances, I’ve been given permission to share that the pool of correct tasters did not include any podcast hosts. These results demonstrate participants in this xBmt were unable to reliably distinguish a beer produced using standard temperature sparge water from one sparged with cool water.

My Impressions: Both batches tasted absolutely the same to me, I can’t identify anything about them that is different, despite a 0.002 OG and 0.26% ABV difference. Whether comparing blind or not, no way no how– these beers were identical to my unimpressive taste buds. And frankly, it’s a great beer for my tastes! I perceive a nice dry, toasty character, not overly caramelly, and noticeably hoppy without being particularly bitter. An easy drinking pint with a gorgeous color that I’ll surely make again.

| DISCUSSION |

The results from this xBmt support the notion cold sparging produces a beer perceptibly no different than sparging with standard temperature water, meaning either can likely be used with little risk of detriment. This being the case, some may be wondering whether or not they should change their method, which I believe is a perfect opportunity for a simple cost-benefit analysis. From a thermodynamics perspective, it’s true that sparging with cool water does actually conserve a slight amount of energy compared to sparging with warmer water. However, the tradeoff is time, as the cool sparge method leads to an ultimately cooler volume of wort in the kettle, which takes longer to bring to a boil.

One potential benefit of sparging with cool water is the reduced risk of tannin extraction, an issue often associated with sparging with water that’s too hot, something I’m personally skeptical even matters. Perhaps the greatest benefit is something Michael Tonsmeire noted in his aforementioned article, that the cool water reduces the temperature of the grainbed thereby making it easier to clean out one’s mash tun.

Additional trials are required to know with any certainty, though I’m inclined to think the OG difference between each batch, minor as it may have been, was a real effect of the variable. Since the cool sparge beer had a lower OG than the standard sparge batch, those concerned with efficiency might want to stick the standard approach.

As for me, I won’t be changing my routine, as it didn’t make my life any easier and actually added more time to my brew day. It’s possible cool sparging may be of use to some brewers, particularly those blessed with perfect brewing water out of the tap, or dunk-sparge BIAB’rs who might not have an easy means of heating additional water. Regardless, the results of this xBmt upheld the point of those who mentioned the method to me — cool sparging was not detrimental to the final product.

What kind of sparger are you? Do you target a specific sparge temperature or do you rinse your grain willy-nilly? Please share your thoughts and experiences in the comments section below!

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