Author: Jake Huolihan

From the book Yeast by Chris White and Jamil Zainasheff:

When the brewer has an appropriate pitch of healthy yeast available, and has the ability to chill the wort down to fermentation temperatures within a reasonable amount of time, the better course for beer quality is often pitching at or slightly below fermentation temperature. The brewer allows the fermentation temperature to rise over the first 12 to 36 hours, until it reaches the desired temperature. The benefit of this process is controlled yeast growth, which often results in better overall yeast health, less leakage through the cell membrane, and thus a cleaner beer profile.

Like many, I was a rather staunch adherent to this advice and truly believed it helped me avoid many of the fermentation related off-flavors I so despise, which made the non-significant results from the first pitch temperature xBmt all the more surprising to me. I began worrying a little less, particularly when it came to ales, which I’ve pitched at around 72°F/22°C without noticing any noticeable detriment to the resultant beer. However, lager styles have become more of a focus for me lately, which led me to wonder about the impact wort temperature at time of yeast pitch for a more delicate style might have.

I tend to ferment right around 50°F/10°C when using most traditional lager strains, and since this is about 20°F/10°C cooler than I can chill my wort throughout most of the year, I’m forced to hold off on pitching for a few hours until my chamber drops the wort to my target fermentation temperature. As annoying as it is to have to return later to finish the job, I’m most concerned about the potential for a contaminant to have its way with my vulnerably fresh wort before the yeast takes hold. Curious for a solution, I decided to test the merits of pitching cool in a fairly extreme way!

| PURPOSE |

To evaluate the differences between two lager beers split from the same batch where one had the yeast pitched at 48°F/9°C while the other was pitched at 80°F/27°C.

| METHODS |

For this variable I decided to go with a simple Munich Helles in hopes of emphasizing any differences caused by the variable. After some consultation with the crew, I decided to use a yeast strain other than the hearty Saflager W-34/70 I’d be relying on so much and went with Saflager S-23 instead.

Munich Helles

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.5 gal 60 min 43.8 IBUs 4.8 SRM 1.048 1.013 4.6 % Actuals 1.036 1.01 3.4 % Fermentables Name Amount % Weyermann Pilsner Malt 12 lbs 99.79 BlackPrinz 0.4 oz 0.21 Hops Name Amount Time Use Form Alpha % Hallertau Magnum 15 g 60 min Boil Pellet 12.5 Hallertauer 90 g 30 min Boil Pellet 2.4 Notes Water profile: Yellow Balanced from Bru’n Water Spreadsheet

I started my no sparge brew day by lighting the flame under my kettle of brewing liquor that had been previously adjusted to my target profile.

As the water was heating, I measured out and milled the grains then placed the grist in my empty converted cooler MLT.

Using the underletting method, I transferred the slightly overheated strike water to my MLT before checking the mash temperature, which was a skosh higher than my 152°F/67°C target.

After an abbreviated 30 minute mash I drained my mash tun completely to collect the full volume of sweet wort in my boil kettle.

The wort was then boiled with hops added as laid out in the recipe.

I began chilling the wort at the end of the 60 minute boil.

Once the wort reached 90°F/32°C, I gently stirred to ensure homogeneity then racked 5 gallons into a fermentation keg that I sealed and set inside my warm house. I then turned the water to my IC back on and continued chilling the remaining wort to 58°F/14°F, which is slightly warmer than my cold winter groundwater here in Denver, CO.

I placed the cooler wort in my fermentation chamber controlled to 48°F/9°C, my target pitch temperature for this batch, to finish chilling. A hydrometer measurement at this point showed my efficiency was disappointingly low, an issue I’ve regularly experienced when using methods to reduce oxidation during the mash. Oh well, I figured it might actually serve to emphasize any differences caused by the variable.

It took 2 hours for the cool pitch wort to stabilize at 48°F/9°C, at which point the warm pitch batch was at 80°F/27°C. I rehydrated two packs of Saflager S-23 dry yeast for each beer before pitching.

Once the yeast had been added to each beer, I placed the warm pitch keg next to the cool pitch batch in the cool fermentation chamber. While I’d normally sandwich the temperature probe between the two fermentors, I was concerned the warm beer would cause the compressor to stay on long enough to reduce the temperature of the cool beer too much. My solution involved letting the probe dangle in the chamber with the controller set to my target fermentation temperature of 50°F/10°C in order to let the warm pitch beer finish chilling before placing the probe between the kegs.

I returned a few times to check on the beers over the following 24 ours and observed bubbling from the warm pitch beer a mere 8 hours after pitching the yeast. I noticed the first signs of activity from the cool pitch batch around the 24 hour mark, which is also when both beers had reached the same temperature and I placed the probe between the kegs. Both beers appeared to be done fermenting after 10 days, presumably due to the lower OG, though I noticed the warm pitch batch did slow down a couple days prior to the cool pitch batch. An initial hydrometer measurement showed the cool pitch beer had attenuated to 1.010 SG while the warm pitch beer was sitting at 1.008 SG. I raised the temperature to 56°F/13°C and left the beers alone for a few more days before taking another round of hydrometer measurements that revealed no change, indicating FG was reached.

I pressure transferred the beers into sanitized and purged serving kegs, which I placed on gas in my keezer to carbonate.

To hasten clarification, each keg was injected with gelatin fining and left to condition for a week before I began serving them to tasters.

| RESULTS |

A panel of 20 people with varying levels of experience participated in this xBmt. Each taster, blind to the variable being investigated, was served 2 samples of the beer that was pitched cool and 1 sample of the beer that was pitched warm in different colored opaque cups then instructed to select the unique sample. While 11 correct selections would have been required to achieve statistical significance, a total of 15 tasters chose the different beer (p<0.05; p=0.0002). These results indicate participants in this xBmt were capable of reliably distinguishing a Helles where the yeast was pitched into 80˚F/27˚C wort from the same beer where the yeast was pitched at 48˚F/9˚C.

A brief comparative evaluation of only the two different beers was completed by the 15 participants who made the accurate selection on the triangle test, all remaining blind to the nature of the xBmt. The cool pitch beer was preferred by 7 tasters, 5 reported liking the warm pitch beer more, and 3 had no preference despite noticing a difference.

My Impressions: I experienced these beers as being pretty darn similar, much more so than I originally expected. However, with some effort, I was able to consistently identify the odd-beer-out in multiple semi-blind triangle tests. To me, the cool pitch beer had a slight hint of sulfur that was absent in the warm pitch beer, and while neither were offensive, I preferred the one pitched warm for its cleaner, crisper, and unexpectedly more lager-like character. The beer itself was okay, drinkable, but certainly nothing special, which may have been due to my efficiency issues.

| DISCUSSION |

An undebatable truth – yeast activity is positively correlated with temperature, which makes the results of this xBmt showing tasters were able to reliably distinguish between lagers where the yeast was pitched either cool or warm somewhat unsurprising, not to mention it aligns with the conventional wisdom. More interesting to me is the data on preference as well as my own subjective impressions of the beers.

It’s not a far stretch to presume a beer fermented with a traditional lager strain pitched at 80°F/27°C would end up with a stronger ester character than the same beer pitched at 48°F/9°C. This is certainly what I expected, but that’s not how things went down, I actually thought the warm pitch beer had more lager-like characteristics than the cold pitch beer, to the point I chose it as the one I preferred when sampling blind. If the distinguishing factor was indeed sulfur, as I perceived, it’d lend credence to the idea that said element is a standard and, perhaps for some, preferable component of traditional cold fermented lager.

It’s worth noting that the wort from the warm pitch batch was hit with yeast at a temperature quite a bit warmer than most homebrewers chill to; it’s entirely plausible a smaller delta in pitch temperature between the batches would have resulted in differences that were even more subtle, possibly to the point of being indistinguishable.

But that’s for a later xBmt! For now, I’ll rest a little easier pitching yeast at whatever reasonable temperature my chiller is capable of bringing my wort down to.

If you have any experience pitching yeast into warm wort or thoughts about this xBmt, please share in the comments section below!

Support Brülosophy In Style!

All designs are available in various colors and sizes on Amazon!

Follow Brülosophy on:

If you enjoy this stuff and feel compelled to support Brulosophy.com, please check out the Support Us page for details on how you can very easily do so. Thanks!

Advertisements

Share this: Facebook

Twitter

Pinterest

Tumblr

Email



Like this: Like Loading...