Author: Brian Hall

Quickly cooling wort results in the coagulation of proteins and other solids into large chunks called cold break that readily drop out of solution. Such a process is said to be beneficial in that it hinders the formation of DMS, halts the isomerization of alpha acids, reduces the risk of contamination by making it possible to pitch yeast sooner, and allows for the transfer of clearer wort to the fermentor.

Perhaps the most popular way homebrewers accomplish this is by using a copper immersion chiller, which in addition to being relatively inexpensive and easy to use, has very high thermal conductivity, meaning killer chilling power. Another common method involves running the wort through a plate chiller, made of many thin layers of stainless steel, while cool water flows in the opposite direction.

Both immersion and plate chillers are designed to accomplish the same task with one’s decision on which to use usually a function of their particular setup. I’ve used both options extensively in my brewing and have found an immersion chiller works better for standard batch sizes while I pull out my plate chiller for anything over 10 gallons. Having previously never considered chiller type as having any impact on my beer, a recent conversation with the crew caused me wonder if maybe it did, so I performed this xBmt to see for myself!

| PURPOSE |

To evaluate the differences between 2 beers of the same exact recipe where one was chilled with an immersion chiller and the other was chilled with a plate chiller.

| METHODS |

Wanting to go with a style that would let any differences caused by the variable to shine, I decided to brew a pale lager for this xBmt. After having an amazing pFriem Pilsner while hanging in Yakima, WA during the 2017 hop harvest, I emailed the brewery to ask for the recipe and they informed me it was included in Dave Carpenter’s new book, Lager: The Definitive Guide to Tasting and Brewing the World’s Most Popular Beer Styles.

pFriem Pilsner

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 35.8 IBUs 3.5 SRM 1.049 1.010 5.1 % Actuals 1.051 1.011 5.2 % Fermentables Name Amount % Pilsner (2 Row) Ger 9.625 lbs 95.68 Carafoam 4.96 oz 3.08 Acid Malt 2 oz 1.24 Hops Name Amount Time Use Form Alpha % Perle 17 g 60 min Boil Pellet 8.3 Tettnang 8 g 60 min Boil Pellet 4.2 Tettnang 21 g 10 min Boil Pellet 4.2 Saphir 14 g 10 min Boil Pellet 3.7 Select Spalt 14 g 10 min Boil Pellet 5.1 Tettnang 21 g 10 min Aroma Pellet 4.2 Saphir 14 g 10 min Aroma Pellet 3.7 Select Spalt 14 g 10 min Aroma Pellet 5.1 Yeast Name Lab Attenuation Temperature Saflager Lager (W-34/70) DCL/Fermentis 75% 48°F - 59°F Notes Water Profile: Ca 65 | Mg 0 | Na 0 | SO4 45 | Cl 40 | pH 5.5 Download Download this recipe's BeerXML file

The day before brewing, I collected the RO water for both full volume BIAB batches.

The next day, I began heating the water with my heat stick several hours ahead of time and milled the grain during the wait.

Once strike temperature was reached, I dropped the bagged grains into each each kettle and stirred gently to fully incorporate.

Since pFriem uses a step mash, I decided to do the same and mashed in both batches for an initial rest at 142°F/61°C.

After a 30 minute rest, I added the same amount of boiling water to each mash to raise them up to the second rest temperature.

An hour later, I removed the bags from both kettles and lit the flames under each.

I weighed out the kettle hop additions while waiting for the worts to heat up.

Both beers were boiled for 60 minutes with hops added as stated in the recipe.

Having staggered the start of each batch by 20 minutes, I quickly chilled the one to finish boiling first with my Hydra immersion chiller, which brought it down to 63°F/17°C, then racked it to a 6.5 gallon glass carboy.

When the second batch was was finished boiling, I let it settle briefly before running it through my Therminator plate chiller directly into a 6.5 gallon glass carboy, it was at the same 63°F/17°C as the other batch.

Hydrometer measurements showed both worts were at the same OG.

I placed the full carboys next to each other in my chamber and left them alone to finish chilling to my desired lager fermentation temperature of 50°F/10°C. I then stole some leftover wort from either batch, pitched a pack of W-34/70 into each, and let them get going overnight.

I pitched the yeast the next morning and noticed similar activity in both within 16 hours.

After 3 days, I began gently raising the temperature over the course of a few days until signs indicated fermentation was complete. Hydrometer measurements taken after a 3 day diacetyl rest at 66°F/19°C showed both beers had achieved the same FG.

I proceeded with kegging the beers under light pressure.

The filled kegs were placed in my keezer for an overnight cold crash, after which I fined with gelatin. Following 4 weeks of lagering on gas, both beers were clear, carbonated, and ready to serve.

| RESULTS |

A total of 24 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the immersion chiller beer and 1 sample of the plate chiller beer in different colored opaque cups then asked to identify the sample that was unique. At this sample size, 13 tasters (p<0.05) would have had to select the unique sample in order to reach statistical significance, though only 9 (p=0.41) made the correct selection, indicating participants were unable to reliably distinguish a Pilsner where the wort was chilled with an immersion chiller from one where the wort was chilled with a plate chiller.

My Impressions: I made a total of 12 semi-blind triangle test attempts over 2 separate tasting sessions and only selected the odd-beer-out 4 times, which suggests my performance was no better than random chance. Even prior to being carbonated or chilled, both beers tasted exactly the same to me. As a fun aside, I was able to get my hands on some actual pFriem Pilsner and tasted it next to my version. They were surprisingly similar, so much so that informal triangle test attempts were too difficult for me to tell apart.

| DISCUSSION |

The immersion chiller used for this xBmt is made of copper and was in direct contact with the wort from the last 15 minutes of the boil throughout the 5 minute duration of chilling. There’s some evidence that copper being in contact with wort can reduce the concentration of hydrogen sulfide, a common compound produced during fermentation. Plate chillers are made from stainless steel, meaning wort chilled using such a device never comes into contact with copper and, especially when using lager yeast, could potentially end up with a stronger sulfur characteristic. However, that didn’t seem to be the case in this xBmt, as tasters were unable to tell apart Pilsners chilled one way or the other.

In addition to the material each is made of, there are a few other differences between these chillers I thought might have an impact. Whereas immersion chillers chill the entire batch of wort at the same time, plate chillers chill only the wort that’s flowing through it, leaving the rest to sit in the kettle at near boiling temperatures, which might be presumed to increase bitterness due to continued isomerization of alpha acids. Additionally, since DMS forms more rapidly in wort that’s above 140°F/60°C, the plate chiller batch would have been at a higher risk for this as well. Finally, since plate chillers chill the wort on its way to the fermentor, any cold break that’s formed during the chilling process ends up there too. Not that it has much of an impact anyway.

I speculate that laboratory analysis might show these beers have some quantitative differences, but to the instrument that dictates most brewing practices, the human palate, any impact of the variable was absent. As such, I’ll continue my practice of using the method that best suits my process and equipment.

If you have thoughts about this xBmt, please feel free to share in the comments section below!

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