Author: Matt Waldron

In my quest to make better beer as cheap and as fast as possible, I’ve toyed with many variables in my brewing, particularly since transitioning from batch sparge to Brew In A Bag (BIAB). One such variable is the vorlauf step, which involves gently transferring sweet wort from the bottom of the mash back into top of the tun with the goal of setting the grain bed and clarifying the sweet wort that gets sent to the boil kettle. Commonly performed at the conclusion of the mash just prior to running off, many accept the vorlauf as essential to avoiding unwanted astringency caused by tannins leeched from the grains as well as producing a clearer beer. However, there’s been some chatter lately about the potential meaninglessness of this step, with some claiming the process eliminates too minimal an amount of grain to have any positive impact.

Back when I used the batch sparge method, I would vorlauf because it’s what I learned to do and didn’t really complicate things. Then I moved to BIAB where full volume mashes and removing spent grains from the sweet wort (instead of the other way around) was believed by many to make vorlaufing an unnecessary step. Really? I wondered about the extent to which a vorlauf would effect the perceptible characteristics of my finished beer, whether it resulted in a quality improvement or if I’d been performing a meaningless method purely out of an appeal to authority? Time to take a closer look!

| PURPOSE |

To evaluate the differences between 2 batches of the same beer where one had the vorlauf step performed at the end of the mash while the other did not.

| METHODS |

To get a good idea of the impact of vorlaufing, I opted to brew a clone of Firestone Walkers’s very pale and brilliantly clear Pivo Pils, managing to get everything the recipe called for except floor malted German Pilsner malt.

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5 gal 90 min 36.6 IBUs 2.9 SRM 1.050 1.011 5.1 % Actuals 1.048 1.01 5.0 % Fermentables Name Amount % Pilsner (Weyermann) 9 lbs 100 Hops Name Amount Time Use Form Alpha % Magnum 15 g 60 min First Wort Pellet 12 Select Spalt 28 g 10 min Boil Pellet 4.8 Select Spalt 28 g 5 min Boil Pellet 4.8 Saphir 57 g 5 days Dry Hop Pellet 3.5 Yeast Name Lab Attenuation Temperature Bohemian Lager (2124) Wyeast Labs 71% 48°F - 58°F

I chose to use the vitality starter method for this xBmt and my brew day began with me pitching 2 packs of Wyeast 2124 Bohemian Lager yeast into 2 liters of starter wort then allowing it to spin on a stir plate while I brewed.

I proceeded to measure out and mill two equal sets of the same grain. The batches were brewed back-to-back and treated exactly the same with the exception of the variable in question. Both batches were mashed at the schedule written in the recipe. As I began heating to mashout, the non-vorlauf batch was left alone while the other batch had approximately 9 gallons of sweet wort pulled from the bottom of the tun and gently placed back on top of the mash. My brewer-wife Marie performed this process slowly and evenly to avoid channeling or disturbing the grain bed.

The vorlauf process was relatively simple and required only slightly more effort than not vorlaufing. The bag was then removed and the wort boiled for 90 minutes with hops added according to the recipe. At the conclusion of the boil, I chilled the wort and took hydrometer readings that revealed a slight difference, with the non-vorlauf batch coming in at 1.048 SG while the vorlauf batch was sitting slightly higher at 1.050 SG.

Differences in color and clarity were easily discernible at this point. Given each batch was made with identical ingredients on the same system, the only thing I can think of to account for this difference is the vorlauf step. I was very curious to see how this might change throughout the fermentation process. Both fermentors were placed in my temperature controlled chamber and left to finish chilling to 58°F before I evenly split the starter between them. Fermentation was ripping along within 24 hours and I noticed the non-vorlauf batch possessed a larger, thicker, and darker krausen. Interesting.

Utilizing the quick lager method, I gently began to ramp the temp after a few days of active fermentation then let the beers sit warm to ensure complete attenuation and clean up any undesirables. By 2 weeks in, both batches had had been ramped down to lager temp. I was expecting them to be a bit more similar at this point, but that didn’t appear to be the case, as the vorlauf batch looked much clearer and darker than the non-vorlauf batch. I let the beers lager at 34˚F/1˚C for 10 days before I hit them with the dry hops. Five days later, I fined each batch with equal amounts of Biofine Clear and let them sit for 36 more hours. Still unhappy with the clarity, I dosed each with a tad more Biofine to try to push it along then proceeded to package 12 hours later. A hydrometer reading at this point revealed both beers finished at 1.010 SG, putting the vorlauf batch at 5.3% ABV and the non-vorlauf batch at 5.2% ABV.

I racked the beer to kegs and placed them in my kegerator where they were force carbonated. Unfortunately, my attempt to reproduce the beautifully clear Pivo Pils had failed, as the beers maintained a hazy appearance. However, they were tasting pretty damn good when it came time to collect data.

| RESULTS |

I collected data for this xBmt just prior to the start of the Miami Beer Fest, as I’d arrived early to set things up and wanted to catch tasters with fresh palates. Participants included 44 craft beer enthusiasts, professional brewers, brewery staff, and homebrewers. Each taster was blindly served 1 sample of the vorlauf beer and 2 samples of the non-vorlauf beer then asked to select the one that was different. In order to achieve statistical significance with this sample size, 21 participants (p<0.05) would have had to accurately identify the vorlauf sample as being unique. In the end, 20 tasters (p=0.063) made the correct selection, suggesting this pool of participants was not capable of reliably distinguishing between the vorlauf and non-vorlauf beers.

Since the results failed to reach significance, the following information should be interpreted with caution, as it is potentially meaningless. The 20 participants who were correct on the triangle were subsequently instructed to complete a brief evaluation comparing only the 2 different samples. When asked about preference, 8 reported preferring the non-vorlauf sample, 3 said they liked the vorlauf beer more, 7 had no preference despite perceiving the beers as different, and 2 felt there was no difference between the samples. Tasters were then instructed to select the sample they thought was produced using the vorlauf step, each sample got 10 votes.

My Impressions: I perceived the non-vorlauf beer as having a grainy, Pilsner malt driven aroma that tamed the hops while the flavor was a bit breadier with early carbonated samples having slightly more body. The vorlauf beer let the hops fly a bit more and had a cleaner flavor with a slightly crisper mouthfeel. The differences were slight, but knowing what I was looking for, I was able to accurately identify the different beer in multiple triangle tests. In the end, I preferred the vorluaf beer due to the crisper sting and aroma from the hops, and its clarity is an aesthetic thing that plays to my overall enjoyment.

| DISCUSSION |

Performed as a matter of course by brewers of all methodical ilks, the vorlauf is presumed by many to reduce the risk of tannin extraction from grain bits making it to the boil. However, despite how easy it is, some have begun to question whether vorlaufing actually makes a difference on the homebrew scale, with many who have ditched the process claiming no negative effect. Indeed, the results from this xBmt support the doubters’ notion, as participants were unable to reliably distinguish a beer produced with a vorlauf from one made without it.

While the comparative analysis completed by those who were accurate on the triangle test is statistically junk, I found it interesting enough to comment on. Grain of salt alert! I’m big believer in the adage my grandmother taught me that if something doesn’t look good, no one will want to put it in their mouth (pretty sure she was referring to consumables), and as they say, we taste our eyes first. But our participants are served samples in opaque cups, meaning they have only their noses and tongues to rely on. The fact a larger portion of tasters preferred the non-vorlauf sample really caught me off guard and made me wonder if some might have been swayed had the samples been served in clear glasses, the clarity perhaps biasing their preference.

Being that this is only a single point of data, I’d caution against making any absolute conclusions. As for me, since vorlaufing did give an extra edge on my efficiency and seemed to squeeze out a bit more clarity, I plan to continue doing it for now… at least until results from future xBmts suggest something different.

Do you vorlauf or have you decided it’s not worth the time? Feel free to share your experience, thoughts, and questions about vorlaufing in the comments section below!

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