Author: Ray Found

Brew In A Bag (BIAB) has become a staple of the modern homebrewing landscape, often touted as the easiest introduction to all grain brewing because it requires little more than an over-sized kettle and fabric filtration bag. Unlike other lautering setups that involve removing the wort from the grain, the fine mesh bag allows the brewer to remove the grain from the sweet wort, the key advantage being that it allows for mashing and boiling in the same kettle. A brilliantly simple solution.

BIAB was initially met with some skepticism and early admonitions were many, the most common being to refrain from squeezing the bag for fear it might lead to the extraction of tannins from the grain husks. Undoubtedly, this early guideline contributed to the broadly accepted notion that BIAB resulted in worse extract efficiency than other mash methods. However, BIAB brewers are now commonly implored not to heed the lore of antiquity, and our xBmt on squeezing the bag supports the idea that it may not be as detrimental as once believed.

With the exception of BIAB, all other mash methods demand the use of at least 2 vessels, one for mashing and one for boiling. I’ve been using a mash/lauter tun (MLT) batch and no sparge brewing since I made the switch to all grain years ago, and while I’ve used a fabric filter in my MLT, I’ve never actually brewed a true BIAB batch. My friend Wes, on the other hand, does often and we’ve found his beers tend to skew less bitter than mine, and not deliberately so. For some reason, they deliver less perceived bitterness than mine even when expected IBU is the same, hence our creation of the “WesIBU” unit of measurement.

I’ve long accepted that one’s choice of mash method was purely personal preference and had little if any impact on beer quality. But Wes, wanting to figure out the bitterness issue, has long pushed for a comparison of our approaches. Admittedly bored by the idea and a little annoyed with Wes’ yearlong insistence, I eventually relented.

| PURPOSE |

To evaluate the differences between beers of the same recipe brewed using either the BIAB method or no sparge method.

| METHODS |

I went with a simple Vienna Lager for this xBmt in hopes of emphasizing any differences caused by the variable.

Mashing Vienna

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5.8 gal 60 min 31.6 IBUs 8.8 SRM 1.046 1.011 4.7 % Actuals 1.046 1.011 4.6 % Fermentables Name Amount % Vienna Malt (Weyermann) 11 lbs 97.78 Pale Chocolate Malt 4 oz 2.22 Hops Name Amount Time Use Form Alpha % Magnum 15 g 60 min Boil Pellet 12 Saaz 44.9 g 15 min Boil Pellet 3.2 Yeast Name Lab Attenuation Temperature German Lager (WLP830) White Labs 77% 50°F - 55°F Notes Water Profile: Ca 55 | Na 0 | Mg 0 | SO4 67 | Cl 55 Download Download this recipe's BeerXML file

After weighing out the same amount of grains for both batches, I ran each through a single pass of my 3-roller mill.

Accounting for the lower absorption rate of the BIAB batch due to squeezing, it required slightly less water than the no sparge batch. Starting with RO water, I adjusted each volume of water to the same profile then began heating them. Hitting precise mash temperatures when using unfamiliar methods is never straightforward, but I was pleased with how close they were to each other.

Despite being mashed in a kettle that was wrapped with an insulative blanket my grandmother made, the BIAB batch precipitously dropped 6°F/4°C over the course of an hour long mash, while the no sparge mash only lost 1.5°F/0.9°C. Since the comparison was between mash methods, this was determined to be a function of the variable.

When the 60 minute mash rest was complete for the BIAB batch, which I started a little before the no sparge batch, I removed the bag and gave it a good squeeze as is commonly recommended when using this method.

For the no sparge batch, I did a quick vorlauf before collecting the same same volume of sweet wort as was in the post-mash BIAB kettle.

Both worts underwent vigorous 60 minutes boils.

At the completion of each boil, the wort was very quickly chilled, at which point hydrometer measurements showed the BIAB OG was unsurprisingly a pinch higher than the no sparge wort.

Both worts were allowed to settle for 20 minutes following chilling before being racked to sanitized 6 gallon PET carboys. Once the carboys were filled, differences in appearance were readily apparent.The BIAB wort was clearer with a large, chunky mass of trub at the bottom whereas the no sparge wort was had just a skim coat of a hard packed trub.

Fermentation took off and progressed similarly throughout for both beers, though I noticed the BIAB batch seemed to have a “dirtier” kräusen that left more trub stuck to the carboy shoulders.

At the end of fermentation, the beers still looked dissimilar with the BIAB batch having a much thicker trub cake, which may explain its clearer appearance.

As expected, hydrometer measurements showed the BIAB batch finished with a lower FG than the no sparge beer, likely as a result of the drop in mash temperature.

I proceeded with cold crashing and kegging, opting to skip my usual gelatin fining process.

The filled kegs were placed in my cool keezer and briefly burst carbonated before I reduced the gas to serving pressure. The first pours showed the beers maintained a difference in clarity, only it seemed the roles reversed, as the no sparge beer seemed to be clearing up faster than the BIAB beer.

Even after 6 weeks of lagering, the BIAB batch remained hazier than its no sparge counterpart.

| RESULTS |

A total of 25 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the BIAB beer and 1 sample of the no sparge beer in different colored opaque cups then asked to identify the unique sample. At this sample size, 13 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, while 14 did (p=0.02), indicating participants in this xBmt were able to reliably distinguish a Vienna Lager made using the BIAB method from one produced using the no sparge method.

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 5 reported preferring the BIAB beer, 7 liked the no sparge beer more, and 2 reported having no preference despite noticing a difference.

My Impressions: I found these beers to be difficult to tell apart when excessively cold, though it became easier as it warmed, which I found both surprising and hard to explain. The no sparge beer was, well, normal, not my favorite Vienna Lager ever, but as expected based on my process. My experience with the BIAB beer was somewhat puzzling– at the start of each sip, I perceived it as being generally less characterful with notably less hop flavor, while it finished with a slightly sticky, almost cloying quality. While noticeable when looking, I found the differences largely faded after sampling 8 oz/0.24 L of each, at which point both just tasted like middling examples of Vienna Lager.

| DISCUSSION |

With upwards of 31% of homebrewers relying on the BIAB method to make their beer, many of whom have racked up competition medals, it’s safe to say it’s a legit approach to crafting quality beer. From the beginning, adherents have claimed BIAB produces a beer that’s no different than those made using more common mash methods requiring the use of a dedicated MLT. Having accepted such an assumption as truth, I was resistant to even testing it out, which is why I am, in a word, stunned that participants in this xBmt were capable of telling apart a Vienna Lager made using the BIAB method from the same beer made via no sparge.

Considering the similarities in observed differences in appearance between this xBmt and our recent one on squeezing the BIAB grain bag, it would seem something about the squeezing process is responsible for producing haze. While results from the former weren’t significant, it’s possible whatever caused the haze in the BIAB beer from this xBmt is what led to tasters being able to distinguish it from the no sparge beer.

However, some other factor could be the culprit. It’s possible the drop in temperature of the BIAB mash is responsible for the difference in character, though I’m skeptical, not only because of our prior mash temperature xBmts, but personal experience– I’ve tasted several similar beers that attenuated differently and in zero cases have I experienced anything like this. The BIAB and no sparge beers were different in a way my humble palate says has nothing to do with a few gravity points, but rather the actual character of each beer.

I won’t attempt to explain away or pretend to understand why some people make perfectly clear beer when squeezing the BIAB bag like it owes them money, but I’ll confess that it is still a mystery to me why some beers drop bright nearly instantly while others require weeks. Ultimately, I’m inclined to stick to my guns on my belief that a BIAB fabric filter is in no way appreciably different than any other lautering device, but that perhaps there’s some element of truth to the old wisdom that squeezing the bag extracts something normally left behind in the spent grain. There’s no way to know based on this xBmt what exactly “something” is, and since neither beer was noted as having an astringent quality, this seems the appropriate degree of ambiguity.

With my preference for the no sparge beer in this xBmt as well as the fact I’m comfortable with my current setup, I’ve no plans to make any changes to my brewing process. If I were a BIAB brewer, I’d simply skip the squeeze in hopes of creating a clearer finished beer, though for those looking to eek every last point of efficiency out of the mash, squeeze away.

But what about Wes?

Since it was ultimately my friend Wes’ experience brewing with BIAB that inspired this xBmt, I asked him to share his impressions on the beers and how these results have impact his approach, if at all.

I went into this xBmt with the expectation of discovering why the “WesIBU” was consistently lower than Ray’s. I enjoy brewing as an avid hobbyist and always value quality results, quick cleanup and continuing to find ways to simplify process. My typical brew day starts at 5:00 PM as the neighborhood gathers together for our brew nights and BBQ. With the simplicity of BIAB, I just carry my entire setup next door to my neighbor’s garage-turned-bar lovingly called “Spanky’s” in a couple quick trips. We’re always completely finished by 8:30 PM.

The BIAB process has kept me involved in brewing with its simplicity and low barrier to entry. We’ve also gotten many people hooked on the hobby when they realize that brewing does not have to be complicated or expensive. My normal equipment to produce 6-12 gallon batches clocks in quite modestly at $30 for The Brew Bag fabric filter plus an inexpensive aluminum pot with valve from the local Mexican market and a Bayou KAB6 burner that manages to heat water and singe anything near it with amazing speed. Several of my friends have the more traditional setups, so it’s always been entertaining to compare and contrast our setups.

Most curious to me has always been the consistently low perception of bitterness when compared with Ray’s batches. We’ve even gone as far as to use the same amount of hops from the same batch with similar observations, though we’ve done a comparison as direct as this xBmt.

I helped Ray brew these beers, so I did not complete the official survey, but I did evaluate the beers at 2 points– once soon after they were kegged and a second time after all data had been collected. I perceived the first samples as being immediately obvious and taking no guesswork. As Ray noted, cold samples were tougher, but as they warmed, the difference was quite plain. My perception was the usual lack of bitterness, or stated differently, a maltier backbone in the BIAB batch.

On the second evaluation done more recently, I brought along my trusty wife whose prowess in baking and cooking is rivaled only by her strong dislike for beer. Her reaction was quite interesting. We performed 3 semi-blind triangle tests with the beers at keezer temperature and in each case, she was able to identify the odd-beer-out on smell alone, something I simply could not reproduce. In her words, the BIAB beer “did not have as much smell.” She also noted there was “another smell” present in the no sparge beer, which I presume might be a stronger hop character.

I already have thoughts on follow up experiments to further explain the variables at play, notably using my normal kettle insulation during the mash and also using a yeast that is known to flocculate extremely well. With the great results I have using the BIAB method, I have no plans to change my current setup. Rather, I’ve found that adjusting my recipes to be about 20% higher in IBU consistently leads to great results that our neighborhood goes through as quickly as I can turn them out.

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

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