Searching For Science In A Glass of Beer Yeast, hops, grain and water all need to combine with biology, chemistry and physics to make a great glass of beer. Charlie Bamforth, University of California, Davis professor of brewing science and author of the new book Beer Is Proof God Loves Us, offers a toast to honor the beverage.

Searching For Science In A Glass of Beer

Searching For Science In A Glass of Beer

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Yeast, hops, grain and water all need to combine with biology, chemistry and physics to make a great glass of beer. Charlie Bamforth, University of California, Davis professor of brewing science and author of the new book Beer Is Proof God Loves Us, offers a toast to honor the beverage.


From a toxic brew to something a bit more palatable: a nice glass of beer. Just (unintelligible) don't go there. Just in time for the holiday season, all year long, for many of us, beer is proof God loves us - at least that's according to Charles W. Bamforth, with a new book of the same name.

So if you brew your own beer, or you just like to talk about the chemistry of the brewing process, give us a call. Maybe we can help tweak your own recipe or answer a question for you. If you've got something to suggest, our number: 1-800-989-8255, 1-800-989-TALK. You can tweet us @scifri, @-S-C-I-F-R-I, or go to our website and talk with folks on there in our discussion about brewing beer.

Charlie Bamforth is the author of "Beer is Proof God Loves Us: Reaching for the Soul of Beer and Brewing." He's also the Anheuser-Busch Endowed Professor of Brewing Science at the University of California at Davis. He joins us from KXJZ in Sacramento.


Professor CHARLES BAMFORTH (Anheuser-Busch Endowed Professor of Brewing Science, University of California, Davis; Author): Thank you for inviting me.

FLATOW: You're welcome. People have their - they really have their favorite beers, don't they?

Prof. BAMFORTH: They do, and that's fine. There's a beer for everybody. Some people say to me: I don't like beer. That's nonsense. You just haven't found the right beer for you yet. So whether it's a fairly gently flavored product or a very intensely flavored product, there's a beer for you.

FLATOW: And what makes beer I mean, it's a very old product, isn't it?

Prof. BAMFORTH: About 8,000 years, probably. I like to say it's the basis of civilization, and when people first realized they could make beer, they stopped wandering around and they stayed put and made beer.

(Soundbite of laughter)

Prof. BAMFORTH: So it's thanks to beer that we have the world that we have right now.

FLATOW: All right. We're going to take a short break, come back and talk lots more with Charlie Bamforth: "Beer is Proof God Loves Us: Reaching for the Soul of Beer and Brewing." We'll talk about the chemistry of brewing and maybe some trade secrets. Maybe you have some of your own.

Our number: 1-800-989-8255. Maybe you're brewing something this holiday season, and you just can't get it to work right. We'll see if we can tweak it for you. Also, you can tweet us @scifri, @-S-C-I-F-R-I. Stay with us. We'll be right back.

(Soundbite of music)

FLATOW: I'm Ira Flatow, and this is SCIENCE FRIDAY, from NPR.

(Soundbite of music)

FLATOW: You're listening to SCIENCE FRIDAY. I'm Ira Flatow. My guest is Charlie Bamforth, author of "Beer is Proof God Loves Us: Reaching for the Soul of Beer and Brewing." And if you'd like to read some of that, you'll find an excerpt on our website, at

Is it hard to brew beer for yourself? Would you like to try it, Charlie?

Prof. BAMFORTH: Well, I don't brew by myself. I've always been professionally involved in the industry. So I've never gone home and brewed beer. But it's not easy. You know, you want to get it right. And the golden rule if you're going to brew at home is hygiene, hygiene, hygiene, make sure everything's nice and clean. Although beer...

FLATOW: I'm sorry, go ahead.

Prof. BAMFORTH: Although beer is resistant to pathogenic organisms, no pathogens will grow in beer, there are some bacteria that will grow in beer. As far as I know, none that use arsenic.

(Soundbite of laughter)

Prof. BAMFORTH: But there are some that will grow in beer, and you've got to make sure you don't introduce them.

FLATOW: Let's talk about some - let's debunk some of these things about beer. For example, there are a lot of commercials on TV - you hear a lot about water. Oh, this is spring water, this is, well, you know, freshly how important is it to have special water for the beer?

Prof. BAMFORTH: Well, water is important. The first thing, it's got to be clean, and it's not going to have any taints, any flavor defects. But the salt composition does have an impact, particularly things like calcium, because they influence the pH of the brew, and that influences the quality.

So sure, it's important. The truth is that here in Davis, for example, I can make any water I want by taking salts out or adding salt. So, sure, there's the charm or the history of where the water comes from, but you can make the water you want in the brewery.

FLATOW: And here's a question, a tweet that came in from Oberdenny(ph) in New York, said: How do different yeast strains affect the taste of beer? Isn't yeast just yeast?

Prof. BAMFORTH: No, yeast is not just yeast. There are basically two major types. There's the ale yeast for making ales, and lager yeast for making lagers.

It's particularly important in the more gently flavored beers. If you've got a lot of malty-ness(ph) or a lot of hoppy-ness(ph), then the contribution of the yeast is less to flavor. Of course, it's always important for alcohol.

But if you've got a robust, very strongly flavored malty or hoppy brew, the yeast is less important. But the yeast can be very important for certain beer styles like hefeweizen. You've got to use a yeast that is traditionally used for the hefeweizen that gives a nice, clovey, a very high banana flavor, and that is due to the specific ale yeast that's used for making that type of beer.

FLATOW: All right, let's go to the phones, 1-800-989-8255 - Tonya in Madison. Hi, Tonya.

TONYA (Caller): Hi.

FLATOW: Hi, there.

TONYA: I love the show, so I'm so happy to be on it. I had an interesting vantage point that I thought I would throw out there. I work for MillerCoors Brewing Company, and I'm a hops engineer.

And so my particular facility takes hops in the way that - especially if you're home-brewing, you're probably used to seeing them either in the (technical difficulties) itself, dried out, or you're used to seeing it in a pellet form.

And what we have is a CO2 extract, the (unintelligible), which holds the bitterness profile within it. And we break it apart, and so you have your alpha acids, you have your beta acids and your (technical difficulties).

And then we can, in some cases, change the way that the chemistry is set up so that it is light stable because you know if you take a glass of beer and you put it out in the sun, the UV rays will actually attack part of the hops and will allow sulfur to float around and make it give it that skunk smell.

FLATOW: I hate it when that happens. All right, let me get a...

TONYA: Yes (unintelligible), and so some, you know, where you have, like, brown bottles when you do home-brewing, generally speaking, because you put the entire hops pellet or hops cone in your kettle. So you don't necessarily have it as being light stable...

FLATOW: Okay, Tonya...

TONYA: other companies like Miller.

FLATOW: All right. How important let me ask my guest. How important is it, that dark bottle to us, Charlie?

Prof. BAMFORTH: It is very important. If you expose beer to light, it does go skunky - even in a brown glass bottle, if you have really strong light for a long period of time. But it's much worse in a clearer, green glass bottle.

And, of course, Miller are well-known for pioneering these hop products that protect against that skunky flavor. And the interesting thing about those materials also is they help make the foam on the beer, the head on the beer, really, really stable. So you get very stable foam, as well.

FLATOW: And, you know, one of the big choices you make, when you go into a restaurant, they have all these beers on tap, and then you have another dozen bottles of beer. Is it better choose the on-tap, like people normally do? I mean, you say, well, it's on tap. It's got to be fresher, blah, blah, blah. No?

Prof. BAMFORTH: Some people say to me you've got 30 beers to choose from, which do you choose? I say one in a bottle, because the really important thing is beer will deteriorate if you're not careful, both flavor-wise and microbiologically. So you've got to keep it moving.

And if beer's on tap, unless it moves fast through those taps and is served and also the beer lines are kept clean, there's going to be a problem.

Beer in a bottle is more stable. Beer in a can is even more stable than it is in a bottle, both in terms of the - obviously, resistance to light, but also you don't get any air creeping into beer in a can.

FLATOW: Right.

Prof. BAMFORTH: And air's a big enemy of beer. It makes the beer go stale, and you need to avoid air. You also need to keep the beer cold, and that'll slow down those aging processes.

FLATOW: You're especially interested in the bubbles, the foam in the glass. What makes for a good foam?

Prof. BAMFORTH: Well, obviously, you need to have plenty of CO2 in there, carbon dioxide, to generate the foam. But a stable foam on beer is due to protein that comes from the grain. And that is cross-linked by those bitter materials that the caller was speaking about. And that gives a stable foam.

The worst thing you can have, of course, is any lipid or fat or grease or detergent, and that will kill the foam. So what you need is a really clean beer glass. You need to wash it in soapy water, but then rinse it thoroughly with clean water and let it drain naturally. And then when you pour the beer in there with vigor, you'll get a nice - a lot of foam, and it'll survive and lace the side of the beer glass, just beautiful.

FLATOW: Is there a frontier of brewing science, a holy grail of a beer or some sort of...

Prof. BAMFORTH: Yeah, it is, really, it's shelf life. It's flavor stability. Beer is a sensitive topic, a sensitive product. For most beers, they're never better than when they're first brewed and close to the brewery.

And as beer travels and exposed to different climates and so on, it will deteriorate and develop a cardboard or a wet-paper flavor. So the holy grail really is how to build in some robustness to the beer such that that doesn't happen.

But, you know, the beer isn't beauty is in the eye of the beholder. And some people are used to drinking beer that is aged, and they kind of like it. And if you get rid of that character, then they don't like it anymore.

So it's a very complex, almost philosophical issue. But most brewers would err on the side of minimizing staling.

FLATOW: Let's go the special beer town of St. Louis. Hi, Pat.

PAT (Caller): Hi. I have a question, (unintelligible), too, but what I make ale. And I also brew mead, which is a honey wine, basically. But with the ale, I use just fruit and sugar and yeast and things like that. I don't use the hops and things. Is that the difference between an ale and a beer, or is there a difference between ale and beer?

FLATOW: Good question.

Prof. BAMFORTH: Historically, ales were un-hopped beers. But that's really back in the Middle Ages, before hops were widely used. And before the use of hops, they were called ales.

These days, ales - the vast majority of ales worldwide do contain hops. The main difference is, historically, the yeast that is used. An ale yeast would rise to the top of the fermenter, and a lager yeast sink to the bottom of a colder fermentation. And then, of course, the storage. The whole word lager means to store, and the lagering process was storing the product in the cold.

There's some differences in the way in which you use the hops, as well, between ales and lagers. But ales these days mostly do contain hops.

FLATOW: Let me see if I can get one more question in here. Let's go to Will in Brooklyn, home of that's a beer town, Brooklyn.

WILL (Caller): Brooklyn Brewery.

FLATOW: There you go.

(Soundbite of laughter)

WILL: William Lube(ph). I was a beer writer back in the heyday when it was just kind of - the craft brew movement was getting started, back in the mid-'90s, and it was, like, a very exciting time for all the, you know, the craft-brew heads.

And there's a split between the technical brewers and the sort of the seat-of-the-pants artisan brewers, you know, and I think among consumers, too, people who prefer very technically done beers and sort of the surprise you get from something that, oh, comes out different every time you brew it.

And they tend to be German styles on one side, very technical. You know, other styles, maybe Belgian, you know, on the other side of the spectrum. And I kind of see a split between the two. I wonder if Dr. Bamforth, you know, has an opinion on - do you see that split, not just between consumers, but between the brewing community?

FLATOW: Good question, Will. Let me get an answer.

Prof. BAMFORTH: It's a great question. I think most people in the craft sector, certainly the ones that are growing their companies, would realize the benefits and the merits of having control and doing it properly and looking after quality control and hygiene and all of these things. And that's why they've been successful.

You know, I can't think of - well, I can think of one product, and it's another type of alcoholic beverage where you do get surprises. And I celebrated. My thesis is, if I buy a product I'd like to know that it's going to be good. If I fill my car with gas, I'd like to know the car is going to drive. So if I buy a beer, I'd like to make sure it's going to be good. So for me, I like a surprise insofar as I like to perhaps try a new beer, but I'd like to make sure the next time I buy that beer, it is just as good.

FLATOW: Well, if you like a great surprise, it's a great read. Charlie Bamforth's book, "Beer is Proof God Loves Us: Reaching for the Soul of Beer and Brewing." Good holiday book. Thanks for taking time to be with us today, Charlie, and good luck to you. Happy holiday.

Prof. BAMFORTH: It's been a pleasure. Thank you very much.

FLATOW: You're welcome. He's also the Anheuser-Busch Endowed Professor of Beer Brewing or Brewing Science at the University of California at Davis.

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