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Episode 6

Why Beer Gets "Skunked" and Other Scent Science

Gary, Bobby, and Allison explore the complex chemistry of beer's aroma. We figure out why beer gets skunked, the effects of hop and yeast, and why glassware matters for a great beer experience.

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--

CREDITS

Hosts:

Bobby Fleshman

Allison McCoy-Fleshman

Gary Ardnt

Music by Sarah Lynn Huss

Recorded & Produced by David Kalsow

Brought to you by McFleshman's Brewing Co

--

Topics in this episode:

Introduction to Beer Smell

The Role of Barley and Malt

Discovering Hops

Terpenes and Aroma

Importance of Glassware for Beer

Transcript
Gary Arndt:

Hello everyone.

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And welcome to another episode

of Respecting the Beer.

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My name is Gary Arndt and with me

again, as usual as Alison McCoy and

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Bobby Fleshman Today or in our last

episode, we talked about sight.

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One of the senses that we use to

appreciate beer, how a beer looks it's

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foam, it's carbonation, everything else.

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This episode, we want to talk about smell.

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Smell and taste are closely

related with each other.

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They're kind of interlinked

in a lot of ways.

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Something smells bad and may not

taste very good and vice versa.

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So let me start out with the big question.

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Why does beer smell and where

does the aroma come from?

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Bobby Fleshman: Yeah, last time I

got in the weeds about how, where

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these colors come from and, and

it was related to the malt and the

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barley and the proteins and so on.

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And the, the main flavors of

beer are coming from the sugars

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that are derived from the starch

inside of those, those grains.

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The proteins give you some

mouth feel in the end, which

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is separate from, from flavor.

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then you're getting some aromas that

are driving from like sulfur derived

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compounds like dimethyl sulfide.

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And you guys might recognize that.

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If you open a can of, of raw green

beans or corn, you're actually

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getting that in your, in your malts.

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And that's giving you some, some

dimensionality to the finished beer.

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Allison's giving me a cross.

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Allison McCoy Fleshman: Because

you're going down directly to

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green bean juice when you really

should be talking about hops.

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Bobby Fleshman: Well, yeah, I'm starting

with barley and then I'm moving on.

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I just didn't want to say

that I didn't want to say that

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barley just gives you sugar.

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There's there's a lot more to the story.

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There there are amino acids that

contribute to ester production

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and esters are sort of fruity

aromas that people will associate

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with break baking in the kitchen.

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Dark fruits.

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There's a lot of that going on and it's

being derived from that malting process.

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So that's coming from the

Malt side of things Allison

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points out that at some point.

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a few hundred years ago, hops were

discovered as a nice balance to the

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sweetness in beer and preservative

property are, I think the botanist's

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name was Hildegard von Dingen.

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Now

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Allison McCoy Fleshman: I

can say a hundred years ago,

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Bobby Fleshman: a couple

of hundred years ago,

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Allison McCoy Fleshman:

multiply that by a couple more.

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Gary Arndt: That's almost

a thousand years ago.

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Allison McCoy Fleshman: Exactly.

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Bobby Fleshman: Oh geez.

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So it, but it's been adopted widely

though in the brewing industry as is

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almost the only solely the, the, spice by

which we balance the sweetness in beer.

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But there you have it.

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So in these hops, you have what are

known as hard, the hops look like little

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pine cones, little green pine cones.

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And inside of them, you're going to

find hard and soft resins and the resins

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located inside these little yellow glands.

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You can take these hops and

pick them off the vine and open

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them up, see little glands.

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And you just take that and you roll

that, that yellow gland in your hand.

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You'll smell these aromas come off of it.

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Allison McCoy Fleshman:

Hops are very fragrant.

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Bobby Fleshman: Yeah.

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It's kind of like cutting your lawn.

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You can imagine that that's

actually, some of the terpenes are

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shared with hops across all sorts

of fruits and vegetables and, and,

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Allison McCoy Fleshman:

You said the word terpene.

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Let's chat for a second.

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Bobby Fleshman: Yeah.

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This is where I have to nod to the expert.

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Allison McCoy Fleshman: So the terpenes

are these oils that are in so many

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different plants but the, the reason

that you get grass stains is because

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the terpenes in the grass are an oil.

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And so just like you can't really wash

off your oil off your hands without some

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sort of water or without some sort of

soap or surfactant or something the oils

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that are in grass stain your clothes

and you can't get them out because,

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well, oil likes to stick to fabric.

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But those oils are really what

give hops their kind of superpower.

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But the kicker is that the oils don't

really mix with water that well.

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So the hops have to go through several

chemical reactions in order to get them

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to stay in the water and that's what

makes hops one of the hardest things I

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think in the brewing industry to handle

because they're quite finicky when it

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comes to the chemistry that they can do.

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Bobby Fleshman: Right.

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I did misspeak.

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Terpenes are found

throughout the hop plant.

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The, that resin is where you get these,

these bittering compounds that I spoke

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about, but, Allison, you could speak

on that there with these terpenes, you

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have some that are, she'll, she'll give

you the, okay, I'm going to give her,

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she's going to expand a little more.

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Allison McCoy Fleshman: Oh my God.

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Okay.

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So Gary, you asked the question

of what gives a bearded smell.

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Well the kicker is in order to smell

anything, a little bitty molecule has

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to leave the thing and come to your nose

and go into you somehow and trigger your

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brain to think, oh, that's that smell.

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And hopefully it triggers a memory and

it's a lovely memory and you're happy.

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But in some cases it's not so happy,

especially with not so great odors.

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But the hops have, they have these

oils and those are volatile compounds.

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And anytime you've walked past a nail

salon, like in the grocery store or

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whatever and you smell that acetone,

acetone is incredibly volatile,

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that's the nail polish remover.

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These are kind of the same.

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They do not, those molecules do

not want to stay, in the beer.

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And so they are going to, what we call,

be aromatic, they are going to float

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away from the beer and come to your nose.

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And that's really the

first, so you see the beer.

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And you're about to taste it, but

as you bring it closer to your nose,

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those molecules are going to start

to escape and come into your nose.

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And then you're going to smell them.

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Hops contribute more of those kinds

of molecules than the malts do.

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So if there's more hops in the beer,

you're going to get more of that

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experience before you even take a sip

because those molecules are coming to you.

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Bobby Fleshman: And getting out,

getting out of my wheelhouse, I

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can say that there's a difference

between tasting wine and beer.

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And that you should, if your, if

your goal is to taste the beer, you

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should actually swallow it and then,

and then breathe back out to get the,

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the retronasal, attribute where I

don't think that's required in wine.

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I think you can get most of that

inside of your mouth and you don't

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have to consume it to, to get it.

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I think the CO2 is part of

that is why that's true.

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It's evolving those aromas back.

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out of your system

through your nasal cavity.

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Gary Arndt: I know when someone drinks

wine, you see them, you know, they

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swirl it around and they smell it and

there's, Oh, it's, you know, you know,

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they have this, description for it.

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You seldom see people

drink beer that way, right?

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Maybe because it's carbonated.

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You're not going to,

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Allison McCoy Fleshman: that's true.

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The carbon dioxide is going to be

bringing those molecules to you much

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faster because the carbon dioxide

also doesn't want to stay in the,

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Gary Arndt: but I've

also noted what you said.

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the double IPA that you guys

make, 547 has a very strong aroma.

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That's one of the first things

I ever noticed about it.

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And I don't notice that

on most beers at all.

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Yeah.

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it, you know, it has this very strong

orange peel scent that I noticed.

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citronol,

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Allison McCoy Fleshman: I

believe is what that is.

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Bobby Fleshman: Citronol.

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Yeah.

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Brought about by a few different

hops that are high in that oil.

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Mm hmm.

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Gary Arndt: But I've never noticed a

wine that had that strong of an aroma.

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Whereas I don't know if it's just a

unique thing with that, but I've just

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Like nothing, you know, you, you get

hints of things in wine, but with

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certain beers, it's very noticeable.

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Yeah,

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Bobby Fleshman: the, the

double IPA is very American.

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It's, it's a very American style.

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It's nuanced.

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It can be nuanced and it should

be, it should be balanced.

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It's never nuanced.

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So

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Allison McCoy Fleshman: I just

had to do a quick Google search.

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I just looked up the chemical structure

of vanillin, which is the molecule

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that gives you the vanilla flavor.

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And I know that there's a lot of, at

least in chardonnays and stuff, there's

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a lot of vanilla character in wines.

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I'm looking to Gary to

be like, is that true?

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I don't even know.

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Bobby Fleshman: You barrel

derived mostly for that.

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Yeah.

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Allison McCoy Fleshman: So

the vanillin molecule has many

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more, what we call polar groups.

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And so chemists like to use the

phrase, like dissolves, like, so

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if, if the two molecules are more

similar they're going to mix better

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and this is actually true with humans.

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You can anthropomorphize

molecules really well.

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So the more things you have in common

with someone else, more likely you're

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going to hang out with them longer.

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You have nothing in common, you're

like, nope, going to go somewhere else.

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So the wine compounds, I think, have

many more similarities to the water that

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they're in or the wine that they're in,

so they're going to stay there longer.

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So I'm guessing that the Sommelier

folks are swirling their wines to kind

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of coke some of those molecules to

come to their nose, whereas the hops

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are like, I'm not like water at all.

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And they just come up freely.

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Bobby Fleshman: And you'll often pour a

wine through a breather to open it, right?

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Allison McCoy Fleshman: That makes sense.

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Yeah.

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Bobby Fleshman: Yeah.

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Before you drink it.

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Allison McCoy Fleshman: so Gary, you

mentioned our five, four, seven, one of

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the things, I think we have it written

on the can too, is please drink me fresh.

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folks will store our 547, which

is a bad idea because the longer

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it stays in the can, the more of

those hop volatile molecules have

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escaped into the little headspace.

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Bobby Fleshman: We have about 10 mils

of space in each can for them to escape.

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Allison McCoy Fleshman: Yeah.

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And so as soon as you

crack it open, it's like.

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Bobby Fleshman: It smells great!

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Allison McCoy Fleshman: Instantly

and then it's all gone, but

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it's still not in the beer.

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And so you want to drink those

hoppy beers as fast as well.

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Not as fast in one sitting, but you

want to make sure that they don't,

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they don't have a long shelf life.

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Bobby Fleshman: And no shaking the can up.

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Doesn't re introduce the oils.

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Allison McCoy Fleshman: Don't do that.

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Gary Arndt: Not like that.

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This freshness.

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I was here once and I remember, there

was discussion of like, you were going

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to submit it for an award and some of

the people that work here were like,

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They were actually going to take a

road trip to take a batch of it and

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drive it as quickly as possible.

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Allison McCoy Fleshman: To Colorado.

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Yeah.

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Bobby Fleshman: Yeah.

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And keep a webcam moving as they went.

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Yeah.

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Gary Arndt: And I was always kind

of, again, I'm always kind of

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skeptical of a lot of these things.

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Like, yeah, it really

doesn't make a difference.

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It's just sort of a marketing thing,

but you're saying, no, it really does.

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Even if it's in a can, that's

going to make a huge difference.

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If it's just canned versus something

that's been sitting around just

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Allison McCoy Fleshman:

for, well, more for beers.

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Like you said, our five, four,

seven is the one that's like.

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You don't get that with

any of the other beers.

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That's the one that's the most

susceptible to that aging.

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The others I think would be fine.

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Bobby Fleshman: Correlation is not

causation, but to Gary's point, the

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winners of these competitions generally

are within a 150 miles of the competition.

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Now that that's because Denver

has a lot of good breweries.

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yes, that's part of it.

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Allison McCoy Fleshman: But it's also

because chemistry still holds and

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those molecules don't like each other.

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So they escape.

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Bobby Fleshman: So you gotta

get your beer there quick.

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Gary Arndt: Okay.

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Would it be possible to fly it?

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Or was it with the change in pressure?

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Bobby Fleshman: Oh no,

there's a whole thing.

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I never thought of that.

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Oh my god.

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Never thought of that.

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Allison McCoy Fleshman:

I have so many thoughts.

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Well, this is one of the good things about

the fact that our, in our brewery, we've

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got it set up to where the kegs and the

casks are located immediately behind.

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Where we pull them from.

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So where the taps are at our house, we

also have a tap system, but we've got

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our kegs are in the, the, the freezers

and the kegs are in the basement

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and then we've got it drilled up.

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There's a hole through our living

room floor and then we've got

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a nice little tap system there.

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But the pressure differential

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Gary Arndt: You have taps in your house?

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Bobby Fleshman: Oh, they're

really a Belgian tower.

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I got from a museum and it was, it's

not a brag that I spent the money.

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I just found this thing.

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Gary Arndt: That's hardcore.

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Allison McCoy Fleshman:

You've got it separated.

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We've got an ale cooler and

a logger cooler as well.

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Yeah.

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But the, the, the, the, the pressure

differential that you have from

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the basement to the first floor

makes it hellaciously hard to

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pour the beers because of that

off gassing that it goes through.

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Bobby Fleshman: Well, since I

built that, I've learned a lot.

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That's been 12 years or

whatever since I built that.

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And now I've learned a lot more

about partial pressures, which we can

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Allison McCoy Fleshman: Not

go into that later date.

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Don't give away all the fun stuff.

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Gary Arndt: In a previous

episode, when we talked about

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color, we talked about glassware.

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And I also remember having this discussion

where I was skeptical that glassware

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could have anything to do with aroma.

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And so you literally did a test where

you poured, I think it was the 547

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double IPA in two different glasses.

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Allison McCoy Fleshman:

Were you blindfolded?

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Gary Arndt: No, but it was,

I could tell the difference.

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I think one was like a tulip

shaped glass and one was a

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more open mouth glass that it.

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Concentrated the aroma for lack of a

better word in that it had a small the,

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in the glass that had a smaller opening.

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Is that something that, I mean, how, how,

how deep into the weeds are you going

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to go into when selecting glassware?

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I mean, you're also selecting aroma

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Bobby Fleshman: okay, when you go

to Belgium, you'll see that every

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brewer has their own glass, and you

can't have their beer at any bar.

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Unless one of those glasses are available.

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And I think that that's because they have

been meticulously designed, partially

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just marketing and the way they look,

but partially because they are meant to

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enhance the aroma and the whole experience

of that, of their, of their beer.

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And I'd like to see more of that.

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I like to see us, I mentioned us

designing our own glass at some point.

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I'd like to do more of that.

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It, the, the trick is we, we cover

so a gamut of styles here and

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it's hard for us to pick one, but

yeah, it's, it plays into that.

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We have to usually make one

work for about three styles.

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Yeah.

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We can't have one for every single beer.

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Allison McCoy Fleshman: During

the pandemic we switched over to

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single use plastic cups because.

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in pandemic times, we

did different things.

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Anyway, so when we went back to

glassware, we decided to just reduce

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it down to just four glasses that we

could get to match as much as possible

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and optimize the glassware to all

the different styles that we serve.

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But one of them is our Hildegard Pilsner.

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So the Hildy, she's a, Czech

Pilsner gorgeous glass.

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that's like a really tall one so you can

see how clear it is it's got a really

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nice foam on the top, but Hildy has really

subtle hop aromas and Bobby figured out

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that the more traditional style would be

this bigger, wide open mouth dimple mug.

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And I think the experience of the beer

is so much different, even though it is

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to style more in line with the checks

to do the bigger, thick dimple mug.

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That's got a really wide mouth because

of the subtle hop aromas in the Hildi.

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I really like her having the

more closed concentrated.

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Hop glass.

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Bobby Fleshman: Which was kind of

confusing because that enhances the,

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the hop aroma, which I wouldn't expect

from Allison to be into as much.

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Allison McCoy Fleshman:

Well, I, well, it, I mean,

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Bobby Fleshman: yep.

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Allison McCoy Fleshman:

I'm being objective here.

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You know.

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That's true.

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Gary asked, does the glass matter?

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It does.

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I was like, I think it does.

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Bobby Fleshman: I wanted to

get to one little anecdote

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about glassware very quickly.

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Miller Lite was created, When was that?

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In the late 60s, early 70s, it

launched the light beer revolution.

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True.

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Gary Arndt: I think I

want to say late 70s.

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Bobby Fleshman: It was late 70s.

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Okay.

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So, so Miller light was created, but it

couldn't be created and packaged in a

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light glass, a clear glass because that

would have gone skunky and then we can

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go into the science as to why Sunstriking

a beer makes it smell like a skunk but

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needless to say the ingredient that...

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it's a hop acid basically that turns into

that same aroma you get from a skunk from

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a skunk, and, it happens in the sunlight.

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The only way they were able to do

that in mass at the scale they were,

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they had to invent a new hop acid

and they had the patent on that acid.

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They created it synthetically.

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they, they reduced an existing one by

adding protons and boom, they created

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what was a more of a, it was a more

stable hop acid and it didn't go skunky.

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B.

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As a side effect, it made magnificent

foam, and so they named it the

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Champagne of Beer and so on and so on.

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Allison McCoy Fleshman: Is

that where that came from?

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Bobby Fleshman: It was not planned, but as

they made this want to solve one problem,

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they solved two, or they created another

benefit, and they led the charge in the

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light beer revolution for a good while,

and they, they named it L I T E, and I

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think that was from the very beginning.

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But now you've seen many other brewers

step in and use the same sort of hop

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ingredient, but they, but they didn't have

access to that for a long time, if ever.

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So they had brown glass

for their light beers.

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So they were the only ones with

that presentation because they had

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the monopoly on that chemistry.

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Gary Arndt: When you

say they added protons.

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Bobby Fleshman: Yes, it's, it's

called reducing in chemistry.

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So you just hydrogen?

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Yeah, yeah, yeah.

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Sorry.

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Yeah.

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I am a physicist, so

sometimes I slip into that.

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Allison McCoy Fleshman: Oh no,

chemists use that too, but technically

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we would call it hydronium as well.

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Bobby Fleshman: Hydronium.

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Let's go with that.

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Sounds even better.

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No, that's H3O plus.

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Gary Arndt: Cause I'm also thinking,

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Bobby Fleshman: what

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Gary Arndt: did they transmute to

a different element or something,

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Bobby Fleshman: right?

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That's high level.

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So they added four hydrogen

atoms to, an ISO alpha acid.

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Which we can talk a lot about

late in future episodes, but acid

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is what makes the beer bitter.

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And they made it stable.

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And then there, there've been

various other ones created since

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then, but that was the one that

really launched Miller Lite.

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Allison McCoy Fleshman: You know,

there's a picture of the, oh,

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it's, it's one of the primary,

advertisements of Miller High Life.

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There's this 1960s woman and

she's looks like she's the

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housewife and she's so excited.

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And she's like, Miller High Life,

you have the champagne of beers.

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I'd really like to think that

she's the scientist behind it all.

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And she's like, I had developed

this isomerized alpha acid

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and no one else knows.

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And it's patented.

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Yay.

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Just saying that's how I'm going to

interpret that picture from here on out.

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Bobby Fleshman: Right.

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We can't finish this episode, Gary,

without talking about yeast, can we?

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There's, they, they give aromas too.

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Bananas!

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Yeah.

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It's gotta be about yeast as

much as it does hops and malt.

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Allison McCoy Fleshman: Let's

talk about the hefeweizen.

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Just, that's

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Bobby Fleshman: the extreme.

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That's one of the extremes.

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Hefeweizen tastes, or smells and

tastes like, bananas and clove.

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Sometimes bubblegum, and all that

stuff is derived from some, some

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Allison McCoy Fleshman: So no bananas

were used in the making of this.

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No,

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Bobby Fleshman: but you can put

strawberry into it and it's awesome.

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So that, that's just a contrast that we've

come to love, a complimentary flavor.

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So, yeah, that, that's one extreme

and then you get cleaner ones.

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Lager yeast tend to be cleaner, although

they kick off some sulfur and, and

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I think that's quintessential for a

good lager at a very, very low level.

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Allison McCoy Fleshman: When you say the

yeast are cleaner, does that allude to

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the fact that other yeasts are dirtier?

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Bobby Fleshman: They, yeah.

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:

They don't make as many of those

fermentation derived aromas and

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flavors as do, say, a Belgian yeast,

which you can put in the same box

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as that, a half a bite of yeast.

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:

And those are going

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Allison McCoy Fleshman: to make

a lot more esters, aren't they?

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Bobby Fleshman: Yeah.

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:

Phenols is another one.

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And sometimes we'll say a phenol in the

extreme case is plasticky or bandaid like.

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I was about

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Allison McCoy Fleshman: to say esters.

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So

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Bobby Fleshman: you want to stay away from

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Allison McCoy Fleshman:

that to some extent.

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:

Chain up a bunch of ester molecules,

you're going to get polyester, which

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I'm sure many of you know what that is.

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Bobby Fleshman: We're not

making polyester in our beers.

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That's not yet a thing.

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Yeah.

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But then in the English, in the English,

yeast are kind of in the middle there.

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They have some really good, I would

say complimentary flavors esters that

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they produce that plays well with

the malts that are made in England.

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Some of the best malts in the world

are made in England they've discovered

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their best yeast that work with those.

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Gary Arndt: All right.

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Well, I think that concludes another

episode of Respecting the Beer.

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Join us next week for another episode.

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And until then, you can go to our Patreon

page or our Facebook group, the links

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to which can be found in the show notes.

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Respecting the Beer
A podcast for the science, history, and love of beer

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