Author: Malcolm Frazer

The latest trend in hopped up beer is a style called Brut IPA, which as its names suggests, is brewed to be as dry as possible and carbonated to the point of sparkling. Given the attenuation limits of most ale yeasts, brewers of this novel style have come to rely on unique methods to increase fermentability, one of which involves using enzymes.

A fairly popular option for brewers of Brut IPA is Amylo 300, an amyloglucosidase enzyme that, according to BSG, “can hydrolyse sequentially both exo alpha 1,4 and alpha 1,6 glycosidic linkages and can therefore be used to degrade starch polymers and maltose to glucose, for the production of high alcohol and low carbohydrate beers.” In essence, use of this product will make a normal wort highly fermentable, upping the attenuation to levels that couldn’t be accomplished without they enzyme.

When it comes to using such enzyme, there’s some debate as to whether it should added during the mash to assist the natural enzymes in the conversion process, or to the beer during fermentation. As a lover of both dry and hoppy, I’ve been itching to try my hand and brewing a Brut IPA and figured I’d test it out for myself!

| PURPOSE |

To evaluate the differences between a Brut IPA produced with Amylo 300 enzyme adding during the mash and the same beer with enzyme added to the beer at yeast pitch.

| METHODS |

The recipe for this Brut IPA was designed to be dry and supremely hop forward.

BRÜt IPA

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 6 gal 60 min 74.9 IBUs 3.9 SRM 1.053 1.008 5.9 % Actuals 1.053 1.007 6.0 % Fermentables Name Amount % Pilsner (2 Row) Ger 12 lbs 92.31 Vienna Malt 1 lbs 7.69 Hops Name Amount Time Use Form Alpha % Galaxy 28 g 60 min First Wort Pellet 14 Galaxy 56 g 30 min Aroma Pellet 14 Nelson Sauvin 28 g 5 days Dry Hop Pellet 12 Yeast Name Lab Attenuation Temperature San Diego Super Yeast (WLP090) White Labs 80% 65°F - 68°F Notes Water Profile: Ca 204 | Mg 18 | Na 33 | SO4 351 | Cl 175 Download Download this recipe's BeerXML file

Having recently relocated to Atlanta from Pittsburgh and yet to unpack my brewing gear, I was fortunate to be invited by Schoolhouse Beer And Brewing to use their Grainfather systems for this xBmt. After collecting the brewing liquor, we began heating it up.

Each volume of brewing water received the same amount of minerals to achieve my desired profile.

We then proceeded to weigh out and mill two identical sets of grain.

Each batch was doughed in at 122˚F/50˚C then ramped to 148˚F/64˚C for a 40 minute rest. It was at dough in that we added a dose of Amylo 300 to one batch.

The mashes were left to rest for 60 minutes.

At the end of each mash rest, we sparged.

While waiting for the wort to boil, we gathered all of the hops needed for these beers.

The worts were boiled for 60 minutes with hops added at the times stated in the recipe.

Following the boil, the worts were chilled and equal volumes were transferred to identical glass carboys. Hydrometer measurements at this point revealed no difference in OG between the worts.

Each wort was pitched with a vial of WLP090 San Diego Super Yeast, after which the same amount of Amylo 300 that was used in the mash of one batch was added to the wort of the other batch.

After oxygenating the worts, they were placed next to each other in a fermentation chamber controlled to 66˚F/19˚C. After a week of active fermentation, the temperature was raised to 70˚F/21˚C to encourage complete attenuation. I left the beers alone for another week before adding the dry hop charge, which mingled with the beers for another 3 days. Hydrometer measurements taken at this point showed the beers had indeed attenuated differently, the one that had the enzyme added to the fermentor finishing a bit lower.

The beers were fined with gelatin, cold crashed overnight, then kegged. After a week of cold conditioning on gas, they were ready to serve to participants. Interestingly, the beer that had the enzyme added in the mash was slightly hazier than the beer where the enzyme was added to the fermentor.

| RESULTS |

A total of 24 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the beer made with Amylo 300 added to the mash and 1 sample of the beer made with Amylo 300 added to the fermentor in different colored opaque cups then asked to identify the unique sample. While 14 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, 18 (p=0.00004) made the accurate selection, indicating participants in this xBmt could reliably distinguish a Brut IPA made with enzyme added to the mash from one made with enzyme added to the fermentor.

The 18 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 7 tasters reported preferring the beer where the enzyme was added to the mash, 8 liked the beer made with enzyme added to the fermentor more, 2 people had no preference despite noticing a difference, and 1 person reported perceiving no difference.

My Impressions: Out of the 3 semi-blind triangle tests I attempted, I correctly selected the unique sample every time, with confidence. To me, the beer made with enzyme added to the mash smelled and tasted maltier, almost as if the Vienna malt came through more intensely. I perceived the beer made with enzyme in the fermentor to be less sweet and lacking in the bread crust character I noticed in the other version. My preference was handily for the one with the enzyme added to the fermentor, as I appreciated the dryness I perceived from that batch.



| DISCUSSION |

A key feature of Brut IPA is dryness, which many brewers of this style accomplish by adding enzyme somewhere during the process, the most common points being the mash or the fermentor. Countering contentions that it doesn’t matter when the enzyme is introduced, tasters in this xBmt were able to reliably distinguish a Brut IPA made with Amylo 300 added during the mash from one where the enzyme was added at yeast pitch.

I’ve sampled a number of commerical Brut IPA and they’ve run the gamut from austere to intensely flavored, low in bitterness to abrasively bitter, and crystal clear to slightly hazy. Moreover, I’ve found some to posses a level of sweetness despite the high level of attenuation, providing a pleasurable balance of malt and hops. Based on the results from this xBmt, it seems plausible some of these characteristics could be driven by the point at which enzyme is added during the brewing process, which provides yet another lever of control for brewers making this style.

This being my first go at making a Brut IPA, I’m not ready to dogmatically accept that enzyme should or shouldn’t be added at a specific point in the process. However, the fact the one made with enzyme added at yeast pitch finished 0.005 SG points lower leaves me inclined to rely on this approach, or perhaps even adding enzymes at both points, if my goal is dryness.

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

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