Bit­ter­ness Just Ain’t What It Used To Be

Craft Beer & Brewing Magazine - - Contents - By Jamie Bogner

New re­search from New Bel­gium into cold-side bit­ter­ness may change the way you think about dry hop­ping.

While past re­search on dry hop­ping has shown that more ex­treme dry-hop­ping reg­i­mens can re­duce IBUS in beer made with ket­tle hops bit­ter­ing, pre­lim­i­nary work from New Bel­gium Brew­ing’s Ross Koenigs sug­gests that dry hop­ping with­out ket­tle ad­di­tions can add far more IBUS than we pre­vi­ously thought. While the work is on­go­ing, here are a few take­aways that may help you bet­ter es­ti­mate the fin­ished bit­ter­ness of your beer. DRY HOP­PING DOES WEIRDER

things to beer than we thought. While con­ven­tional logic—and all ex­ist­ing soft­ware mod­els for cal­cu­lat­ing the­o­ret­i­cal IBUS in beer—say that IBUS can only be gen­er­ated on the hot side of brew­ing (since al­pha acids can only be iso­mer­ized by heat), brew­ers have long sus­pected that dry hop­ping can, in­deed, make an im­pact on the per­cep­tion of bit­ter­ness.

Last year, Stan Hierony­mus wrote in the Au­gust-septem­ber 2017 is­sue of Craft Beer & Brew­ing Magazine® about evolv­ing re­search into IBUS and the strange way that ex­treme dry-hop­ping reg­i­mens can ac­tu­ally re­duce iso-al­pha acids in beers, os­ten­si­bly by caus­ing more of those acids to pre­cip­i­tate out with the dry hops ma­te­rial.

In 2017, Ja­son Perkins of Al­la­gash Brew­ing pre­sented at the Craft Brew­ers Con­fer­ence on a study they con­ducted with Ore­gon State Univer­sity to test the im­pact of dry hop­ping on beer at­ten­u­a­tion and found that by ad­ding dry hops to a fully at­ten­u­ated beer (their sam­ple was Coors Ban­quet), they could cause sig­nif­i­cant ad­di­tional at­ten­u­a­tion in the beer. Over 40 days, those dry hops were able to drop the fin­ished Coors Ban­quet from about 1.014 SG to 1.007, tak­ing the beer from 4.9 per­cent abv to 6.2 per­cent by creat­ing en­zy­matic ac­tiv­ity that broke down non-fer­mentable dex­trins in the beer.

Ap­ply­ing that same ques­tion to dry hop­ping in hazy New Eng­land–style IPAS, New Bel­gium’s Ross Koenigs re­cently pre­sented (at the Big Beers, Bel­gians, and Bar­ley­wines fes­ti­val in Breck­en­ridge) the find­ings of a study he did with a test batch that used no ket­tle hops and four dif­fer­ent lev­els of dry hop­ping. While he’s con­tin­u­ing to re­fine his re­sults with fur­ther test­ing, the pre­lim­i­nary find­ings could be very use­ful for brew­ers whose per­cep­tions of the beer they brew don’t al­ways match the cal­cu­la­tions pro­duced by their brew­ing soft­ware.

One » Dry hop­ping def­i­nitely adds more ac­tual IBUS than pre­vi­ously cal­cu­lated.

“We took an un-ket­tle-hopped base beer and split it out into four fer­men­ta­tions,” says Koenigs. “We did an en­tirely non-hopped con­trol and did three dif­fer­ent dry-hops it­er­a­tions. We did 500 g/hl, 1 kg/hl, and 1.5 kg/hl.”

The IBUS, mea­sured with New Bel­gium’s in-house spec­tropho­tome­ter, were fas­ci­nat­ing. The con­trol batch tested for the ex­pected mar­ginal IBU level (2.3 IBU), but de­spite the com­plete lack of ket­tle hops, IBUS then in­creased dra­mat­i­cally and scaled con­sis­tently, with the 500 g/hl dry hop batch test­ing at 44.9 IBU, the 1 kg/hl batch test­ing at 58.5 IBU, and so on.

Two » Higher dry hop­ping raises the ph of beer.

The con­trol batch in Koenigs’s test reg­is­tered 4.46 ph, while the 1.5 kg/hl batch reg­is­tered a 5.05. The ph moved on a rel­a­tively lin­ear scale, in­creas­ing with the amount of dry hops.

“There’s def­i­nitely a ph rise as you in­crease hops ma­te­rial,” says Koenigs. “The cool part about that, too, is that as you al­ter your ph, it also al­ters your per­cep­tion of bit­ter­ness. As you de­crease ph, to a point, you’ll get a de­creased per­cep­tion of bit­ter­ness, and it’ll just feel more juicy un­til you get re­ally low.”

While un­re­lated to New Eng­land–style IPAS, this is one rea­son more acidic dry-hopped beers, such as dry-hopped mixed-cul­ture farm­house ales or wild ales, present hops in such a fruit-for­ward juicy man­ner at those lower ph lev­els.

Three » Greater dry-hop­ping lev­els do in­crease at­ten­u­a­tion of the beer.

“ABV from the con­trol batch to the high­est is al­most a full per­cent­age point ABV off,” says Koenigs. “Hops ma­te­rial does have gly­co­sidic en­zymes—a com­bi­na­tion of amy­loglu­cosi­dase, beta-amy­lase, a lit­tle al­pha-amy­lase—very, very small. If you look at it in terms of di­astatic power, a base malt will be 150 DP, and this is a 0.2

DP, but it’s enough. Es­pe­cially as you start go­ing up in con­cen­tra­tion of hops ma­te­rial, it will ac­tu­ally start to at­ten­u­ate.”

For brew­ers, this is one of the larger take­aways. If your goal is big­ger mouth­feel from a higher fin­ish­ing grav­ity, heavy dry hop­ping will knock that down, so con­sider that when mak­ing de­ci­sions about el­e­ments such as mash tem­per­a­ture or dry-hops tim­ing.

“The New Eng­land style is gen­er­ally highly un­der-at­ten­u­ated,” says Koenigs. “When we ran lab tests of [fel­low Colorado brew­ers and sem­i­nar par­tic­i­pants] Outer Range Brew­ing and Cere­bral Brew­ing, they had fin­ish­ing grav­i­ties around 5.5 Plato (1.021 SG). The low­est we tested was Weld­w­erks Juicy Bits, around 3.8 Plato (1.015 SG). So brew­ers are gear­ing it to­ward full mouth­feel per­cep­tion.”

Four » IBU is, still, an in­suf­fi­cient way to de­scribe per­ceived bit­ter­ness in dry-hopped beers.

Echo­ing the find­ings of oth­ers, Koenigs found that the trained sen­sory panel at New Bel­gium Brew­ing pegged the blind sam­ples at much lower lev­els of bit­ter­ness than their mea­sured IBUS would sug­gest. As we drank a sam­ple of the 1.5 kg/hl beer to­gether in the tap­room one af­ter­noon, Koenigs said, “The beer you’re tast­ing right there, an­a­lyt­i­cally, that’s a 62 IBU beer. But it doesn’t taste like it. Not even close. With our sen­sory panel, we do he­do­nic scal­ing—one to ten in bit­ter­ness per­cep­tion. This beer ranked about a three. So what we’re see­ing an­a­lyt­i­cally about what we should have isn’t backed up by sen­sory.”

Part of this, Koenigs sug­gests, is an in­dict­ment of how the mea­sure­ment is done. A spec­tropho­tome­ter ag­gre­gates the bit­ter­ing com­pounds and ap­plies a num­ber to them, but it can­not ac­count for other sen­sory in­puts that brew­ers use to ma­nip­u­late the per­cep­tion of those com­pounds. A big step will be de­vel­op­ing use­ful cor­rec­tion fac­tors that soft­ware cal­cu­la­tors can use to ac­count for the im­pacts of dry hop­ping, but that’s still a ways off. As with most re­search in brew­ing sci­ence, more work re­mains to be done to tease out the full im­pact of mod­ern tech­niques and new hops va­ri­eties on dry-hopped beer, but if you found your beer dropped in grav­ity af­ter dry hop­ping or that the bit­ter­ness didn’t cor­re­late at all with the cal­cu­la­tion of your soft­ware, there’s a good rea­son for that.

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