Science Talk

The Science of Cheese; and Scientific American's New Community

In this episode, University of Wisconsin-Madison cheese researcher Carol Chen explains the physics, chemistry and biology of cheese. And Scientific American's Christie Nicholson talks about our new web community. Plus we'll test your knowledge of some recent science in the news. Websites mentioned on this podcast include:;

Welcome to Science Talk, the weekly podcast of Scientific American for the seven days starting November 21st. I am Steve Mirsky. This week on the podcast: Carol Chen helps us celebrate the beginning of the official overeating season with a salute to cheese. And our own Christie Nicholson tells us about the new SciAm community. Plus, we'll test your knowledge about some recent science in the news. First up, Carol Chen—her official title, one of the great science titles, Cheese Application Researcher at the Center for Dairy Research at the University of Wisconsin–Madison. I was in Madison in October and spoke to Carol Chen at a picnic table right outside Babcock Hall, home of the Center for Dairy Research.

Steve: Hi Ms. Chen, good to talk to you today.

Chen: Hello Steve.

Steve: So tell me about your background—you are a food scientist.

Chen: Yes, I am a food scientist; I have a bachelor's degree from the University of Wisconsin–Madison and I've been with the Wisconsin Center for Dairy Research for about 15 years.

Steve: And you are a cheese expert?

Chen: I'm not the big cheese here, but I do know a few details about cheese.

Steve: So, tell everybody, you know, what's cheese? I know that it is a dairy product, but that's pretty much all I know. What is cheese?

Chen: Cheese is actually a really ancient food and of course cheese is made from milk and you start with milk and you end up with cheese and whey as in "Little Miss Muffet".And our center does actually research with both the cheese end and the whey end.

Steve: So, what's the difference between cheese and whey? What actually is whey? Everybody's heard the nursery rhyme, but I don't know what whey is.

Chen: So you start out with milk and you ferment the milk, which means that you have a starter culture in the milk, and …

Steve: Some kind of bacteria.

Chen: … it's a kind of bacteria—and you clot the milk, you use rennet, which is, at one time was, derived from the stomach of calves, but now …

Steve: Is that a protein or an enzyme?

Chen: Right! It's an enzyme.

Steve: So, it's both a protein and an enzyme?

Chen: Right! Yes. Enzymes are proteins, yes. So, you clot the milk, then you look at that point in cheese making, the wad of cheese looks like hard Jell-o; it of course is white and you cut that up and you let some of the serum expressed from the curd and that is the whey.

Steve: And that stuff can really smell bad, can't it?

Chen: Oh no! It doesn't smell bad at all. At that point, in cheese-making, the whey is, it's sweet and other than that, it really doesn't have a lot of flavor—kind of a dairy-milky flavor, but not exactly milk because you've removed some of the proteins and [it] has very little fat in it, so its thin.

Steve: I was thinking, I remember hearing about some farmer in Vermont, where my sister lives, who had used whey as a fertilizer on his fields and people were really upset because I guess at that point it might have smelled really bad.

Chen: It may have, because when they separate the curd from the whey and the curd ends up as the cheese, that whey has many, many uses. Its often further processed and used in other foods as an ingredient or supplemental ingredient. Some older ways to use to whey was to land spread it because it has a lot of nitrogen and sulfur—it's also a good fertilizer.

Steve: So, lot of protein in it?

Chen: A lot of protein.

Steve: And what are some modern uses for whey?

Chen: They use it in the baking industry; they use it in the beverage industry. Just fun: They use it in any food product actually.

Steve: What does it actually do though if you put it in? It just adds proteins or it adds some kind of a, does it do anything to consistency? Why would I put [whey] in a baked good?

Chen: Because it adds nutrients; there is a lot of protein and there's also quite a few minerals in whey and then there is virtually no fat in whey.

Steve: Okay, so now lets go to the real meat of the issue—the cheese. So, the cheese is the other part of the dairy, it's the fat and there is protein and what else is there in cheese?

Chen: Moisture. There is a lot of water in cheese, believe it or not! So, your main components are moisture, protein, fats, and in some cheeses, there is a little bit of, like the mozzarella cheese, there is [a] very, very small amount of sugar and there's quite a few minerals. Cheese is high in calcium and phosphate and other minerals.

Steve: And those bacteria, they are still in the cheese?

Chen: They are still in there. They are in there and a lot of them have a lot of beneficial qualities; and then there's the bacteria that you add and there is natural flora of the cheese as well. And both of those bacteria help to age that cheese.

Steve: It's a good thing to age the cheese.

Chen: That's a good thing. Yes.

Steve: The bacteria are alive. If I buy fresh cheese, those bacteria are still in there cooking.

Chen: Yes, they are still in there; however, any residual sugars that are in a young cheese are typically fermented by the bacteria in that cheese, so once all those sugars are fermented, the bacteria are alive, but they are essentially starving. They are a little bit dormant, so they are not necessarily reproducing but they are there.

Steve: So, cheese will taste differently as you age it because the bacteria are digesting the sugars?

Chen: Sugars and proteins and in some cases fat.

Steve: Now, what's the difference between, you know, cheddar cheese and Limburger cheese. Are they different bacteria? How do I make one versus the other starting with the same raw materials?

Chen: You know, as a consumer that's really a good question, because if you look at the ingredient label for cheddar cheese versus Limburger cheese versus mozzarella versus Jussto Liepa—they all have the same ingredients which are …

Steve: Well, what was the last one?

Chen: Jussto Liepa.

Steve: What's that?

Chen: It is a Finnish bread cheese and it's a unique cheese. You essentially take cheese and after it is manufactured, you slice it thin and then—the traditional way is to bake it in a hearth oven and it browns on the outside.

Steve: That sounds really good.

Chen: You'll have to try some. (laughs)

Steve: So how do I make all these different cheeses with the same set of ingredients?

Chen: So, cheese starts out with milk, you add cultures, enzymes, and salt and the main difference is the bacterial starter culture that you add to the cheese, and there is a wider array of bacteria that you can add.

Steve: So, take me through the actual process whereby the different bacteria are going to turn my milk into cheddar versus say Swiss cheese. What are the bacteria doing that makes the final product different?

Chen: You've really hit on the art and science of cheese making with your question because different bacteria require different temperatures to grow, they grow at different rates, they have different enzyme packages that they use as they grow, and they utilize the raw materials in cheese. So, the rate of acid production—which is the rate at which the bacteria ferments the sugars in the milk—varies and that in turn will affect the flavor and will affect the texture of the cheese. So a cheese maker manipulates the ingredients they add and then the temperatures at which they make the cheese and that helps to develop the different flavors. Another place that bacteria come into play, they are not only very, very important during the fermentation of cheese—sometimes we refer to them as secondary starter; they are bacteria that are not growing while we are making cheese in the vat, but they are growing in the cheese, as it is ripening; so those bacteria also strongly affect the flavor and the texture of the cheese.

Steve: How do they know when to start?

Chen: Well, they are hungry little critters; I mean, their job is to multiply. So, what they do is they take up the sugars and they use that sugar as an energy source and...

Steve: But then, they are not doing in it in the vat; they are waiting until the cheese is finished because of the different environmental conditions at that point.

Chen: The secondary starters are working with a different set of—they use a different food source. Swiss cheese is an interesting example of that because you have one bacteria that produces acid in the vat and you have second bacteria that grows and that's the bacteria that actually ferments its raw materials into flavor-producing compounds and gas, CO2, which forms the ice in Swiss cheese.

Steve: The big holes.

Chen: Yes, correct.

Steve: So, basically, it's all time dependent. There is one thing that's waiting for a step to be achieved and then they are going to kick in and start doing their thing.

Chen: Correct.

Steve: Tell me, what actual cheese science have you personally performed?

Chen: I started out in an analytical group, so I did a lot of analytical and microbiological analysis and then during the first [low fat]love and craze, I helped develop protocols for making lower-fat cheddar, Swiss, mozzarella, that was pretty exciting, and then another project that I've worked on is making mozzarella using cheddaring equipment.

Steve: Oh! That would really be interesting for cheese companies to be able to make two sets of cheeses with the same stuff, right?

Chen: Correct. And mozzarella is typically what they call a pasta filata–style cheese. After the curd is formed, they heat that curd up and they stretch it and they reform it into [a] block. So, it's quite a trick to figure out how to get the right functional and flavor characteristics, but not using that second heating step.

Steve: And that process has been figured out and developed.

Chen: Yes, and it is commercially available in a few cheese plants in Wisconsin.

Steve: And they are actually doing that now?

Chen: Yes, they are.

Steve: That's pretty interesting for those of us who like both cheddar and mozzarella, although anybody who's put in cheddar on their pizzas—I don't understand you people.

Chen: It doesn't look greasy, [right]isn't it? It has a nice cooked flavor though.

Steve: That's true. So, tell me about some of the cheese physics. I saw a poster in the hall here at the Center for Dairy Research on stretch and melt characteristics of cheese. So, what's that all about?

Chen: Well, after I worked on manufacturing protocols, then I kind of grew into the area of cheese functionality and that really refers to machining the cheese—either slicing or shredding; and then also when you melt the cheese what kind of attributes does that have? What I'm really talking about is how it looks, its appearance on that pizza pie, how it stretches and how it melts. And those things are really important because part of the reason why cheese consumption is still on the rise in United States is because cheese is finding its ways as an ingredient into other foods like pizzas, breads—things like that. So, it's really important that cheese has a consistent functionality in these finished foods.

Steve: Like if you want to put some cheese in a Jalapeno popper, you want to make sure that it doesn't explode out of there in the microwave, but it melts nicely inside without leaking out before it is served.

Chen: Yes, exactly. Those are the types of the projects that we have worked on. And essentially we accomplished that by altering some of the rates of acid production in the vat because that influences the chemistry of the cheese and then how it will perform in its end use. Cheese has to conform with the cooking conditions that somebody else specifies, so we are kind of, they tell us what conditions and how the cheeses perform and we can tweak the cheese, so it has the proper functionality. Also, something I haven't brought up is cheese is really a continuous protein matrix with entrapped fat and water and when you control the machinability and the functionality, the key is really paying attention to the protein, what the state is and how the proteins themselves are relating to each other in minerals and other components.

Steve: So in that way, it's similar but different to ice cream because ice cream is a 3-D fat network.

Chen: Yes, very good.

Steve: That's because I interviewed guys at Ben & Jerry's last year about ice cream science.

Chen: Yes, that really shows you what a food scientist does. Food science is a unique field because we apply a lot of chemistry and physics to a food product—a food system—and then in the long run, we get to actually eat the food and evaluate it. So, it really sets it in our head what we are doing in terms of the chemistry and physics of food.

Steve: So, are new cheeses just being made all the time. Is somebody coming up with a brand new cheese that's never existed before?

Chen: That is true. That's difficult though because consumers tend to purchase something they recognize, but there are—initially in the history of cheese making every town had a cheese factory and they produced a unique cheese; and cheese factories down the road from each other, one made a cheddar, the other one made a cheddar [too], but they might be very different [in] character.

Steve: Because of the individual bacterial species that they happen to be working with, they didn't know about that, they have been making cheese since before anybody knew about bacteria, right?

Chen: That's true. They may be using different starter cultures and they may be using different parameters, cook temperatures, and things like that, which made their cheeses unique. But in terms of creating new varieties of cheese, what you more typically see is the fact that the world is becoming a smaller place, so somebody may have traveled in Finland and had this Jussto Liepa cheese and now they are taking that cheese and learning how to make it in U.S. cheese-making conditions, and then they are manufacturing that here, so it looks like a new cheese, but its actually been around for centuries.

Steve: Right, because now we can make any cheese anywhere or you can just have cheeses shipped anywhere. So anybody in the world can get a cheese that they wouldn't have been able to taste a hundred years ago ever.

Chen: Correct.

Steve: Is cheddar the most popular cheese?

Chen: cheddar is still the most popular cheese, but mozzarella has[is] really gaining.

Steve: Yeah, and so in the United States we are talking about, so, cheddar, mMozzarella, and then Swiss cheese?

Chen: Probably Colby, Monterey Jack. One other thing that I should mention—especially in the state of Wisconsin, we have our large manufacturers who are making millions of pounds of ccheddar and mozzarella and Colby and Monterey Jack, but we also have a lot of cheese makers who are smaller and they are really responsible for the resurgence of some of the specialty, artisanal-type cheese.

Steve: So, it's like the whole situation with beer, I guess, in that sense.

Chen: Yes, very similar.

Steve: This was really fun. Thanks a lot.

Chen: You're welcome, thank you.

Steve: For more on cheese science, visit the Center for Dairy Research at (for Wisconsin). Also try for info on everything from Asiago to Zanetti Parmigiano-Reggiano.

Next up, Christie Nicholson—she is the host of the weekly Scientific American 60-Second Psych podcast and she has developed and now runs the new SciAm Community. To find out more, I spoke to her last week in the library at Scientific American.

Steve: Hi Christie, how are you doing?

Nicholson: Hi Steve. I'm well, how are you?

Steve: I'm good. So, you are in-charge of the new Scientific American Community.

Nicholson: I am in charge.

Steve: I'm completely in the dark on this. So, what is the community and how do people get to it?

Nicholson: Yeah! This is something that I think a lot of people have heard tossed around this idea of online communities and probably most people certainly in a certain age range may never have heard of online communities. However, for those who have, they are already very old news, they've been around for, at least popular, for 3 years now, and certainly—I guess, the best definition for people because they've heard of MySpace and Facebook is that the Scientific American Community is a MySpace for science enthusiasts, scientists, experts, journalists.

Steve: Okay, so that translates to the people who know about MySpace and Facebook, but if you don't know about MySpace and Facebook, what is the Scientific American Community?

Nicholson: Yeah! A better definition; it's a place, where you can go to discuss issues and interests with like-minded people that also enjoy science and technology. Online communities have become essentially the new blogs. I mean, blogs have been around obviously, most people have heard of a blog and essentially it's, kind of, like a journal of opinion, but communities have opened up the pla[y]in[g] field. Now we've got enormous numbers of people chatting about things that interest them. There's also social networks, which are slightly different from online communities, social networks being the primary use of connecting with friends in a social way. A community—certainly Scientific American's Community has a niche subject that we're involved in, which is of course, science and technology.

Steve: So, you can go there and you can have discussions about issues of interest within science and technology with other users from all over the world?

Nicholson: From all over the world. The thing about the Internet that a lot of people forget is that it is global, so we are talking about global discussions. I mean the Internet is the first time really in history, in our history of the world, that we have a quick, fast, cheap way to get together globally on an issue, on a topic, which actually presents a tremendous number of opportunities certainly to do with science. Whether it be a scientific problem that people are working on or just discussions and debate of issues that it would be better to talk to somebody, you know, in Germany, who is actually there or in Japan, I mean, and this can easily happen. I mean, the Internet has broken down all barriers of time and space, so …

Steve: What are some of the initial topics that you have seen being under discussion?

Nicholson: Yeah, we've been in beta for about four weeks now and it is already started in and I'm very impressed with the level of discussion, certainly its mostly to do with blogs. What you can do with the Scientific American Community is that you can set up your own profile, you can start your own blog, we've established a platform for you to do that. Plus, on top of that there are also discussion and you can obviously post photos, videos, all kinds of stuff, audio, I mean, basically the sky is the limit. In terms of blog posts so far, we've got a number of authors, physicians, physicists, environmentalists debating on everything from land use preservation to Gary Taubes's new book, Good Calories, Bad Calories, other controversial topics like the woman that you interviewed on the show a couple of weeks ago, Jessica Sachs, talking about microbes, and she just had a post on chickenpox parties that parents are apparently having. There is a tremendous opportunity for uncovering new information. I mean it's certainly something that goes beyond even just interest. Journalists would obviously have, and they already have had a lot of interest in blogs in terms of turning up undiscovered pieces of research in science, are just simply getting an expansive view of the opinions that are out there. The biggest thing with community is [that], because they are proliferating so quickly, is a lot of people think, "Well, how can we possibly have time to go to all these communities?" And they are proliferating. I mean, MySpace actually died back in April, you know, what we say is [it] died because it's kind of plateaued. Facebook has now reached, I don't know how many millions of people, but it's worth $15 billion on the market as of, I guess, last week. So, these things are here to stay and I think its time that everyone kind of get involved and kind of know. You can't get an idea of what a community really is all about until you do get involved and have that back and forth. What the Scientific American Community is going to be able to offer, [more] than any science community for that matter, although the SciAm one is the most extensive of its kind that I know about, is that science by its very nature is something that's open for discussion. I mean, its up there with politics or religion. There is already a company called that's been out there. You can essentially create you own social network in seconds. It's like Blogger. I mean, it is, all of the newspapers and publications will be setting up their own communities this winter.

Steve: Is the SciAm Community refereed in any way? I mean, if I want to start a discussion of, "Whether or Not the World is Flat can I do that?

Nicholson: You can absolutely do that. In fact, yes, you can do that. It is moderated to a certain degree itself. It's self-policed first of all. So any kind of abuse can be reported by all of its members, so there is that kind of self-policing aspect, which is good. People who start discussion threads, like if you were to just start that discussion, you could moderate it and watch it. As it goes, I will be watching over most of the things as much as I can. We also can have limited forum discussions where I can say, "Okay this week we're going to have two special experts or two author discuss, you know, nuclear energy," and that can be closed to the public so that the public can see it, but its just their opportunity[—the experts—]to kind of bat against each other and then the public can be open to it [to offer]at their own opinions. I mean, there's all sorts of things that can happen.

Steve: How do you get there?

Nicholson: Well you get there by going to our newly redesigned site, and up in the upper-left corner is a link to [the] community. The other thing that you can get there through, which is why it happened, certainly its one thing that's going to start the greatest number of discussions, which is on our new redesigned site, we have an ability to comment on every single article. Every article, a user can come in and put in their own opinion, their own input, say that we're wrong, we're right, wonderful, whatever and doing that however you do have to become a member of our community. So, when you go to the site, there is an open box, put in your comment, we'll be prompting you to join [the] community and then your discussion is launched.

Steve: All right. So, check [it] out. Be a member of the community.

Nicholson: Yes, engage; debate. Find your muse; take your place in the new, new media. Its here to stay folks!

Steve: Thanks a lot, Christie.

Nicholson: You're welcome Steve. Thanks. See you online!

Steve: Now it is time to play TOTALL……. Y BOGUS. Here are four science stories; only three are true. See if you know which story is TOTALL……. Y BOGUS.

Story number 1: The obesity epidemic is playing havoc with the standard dosages of prescription drugs.

Story number 2: Agricultural researchers have developed land-deficient skinny peach trees.

Story number 3: Brain studies show that merely having a choice between two outcomes is as satisfying as getting the better outcome.

And story number 4: New studies show that kids with poor attention or behavioral issues in early grade school have virtually no chance to ever catch up academically.

Time is up.

Story number 1 is true. Overweight people already have health concerns, but obesity also means that some prescription medications, especially antibiotics, may be prescribed at too low a dosage; that's according to a study in the journal Pharmacotherapy. It's a complex issue. Fat absorbs a lot of some prescription drugs, not a lot of others. The article notes that the number of individuals with the highest body mass index went up 600 percent between 1986 and 2000.

Story number 2 is true. We now have far-skinnier peach trees. The so-called Crimson Rocket peach trees, is a tall, thinner tree that nevertheless produces full-size peaches. It was developed by Department of Agriculture researche[r]s. A regular peach tree can spread out over about 16 feet. The new trees only have a width of about 5 feet. You get more peaches per acre at the same production costs.

Story number 3 is true. Choice about outcome seems to be as satisfying as looking into the better of two outcomes—even though the subject may wind up picking the lesser of the two options. A study with rats found this to be the case. For more info, check out the November 19th episode of the daily SciAm podcast, 60-Second Science.

All of which means that story number 4, about [how] young kids with behavior issues are most certainly doomed to life-long failure is TOTALL……. Y BOGUS. A study of 16,000 kindergarten kids with behavioral problems found that by the fifth grade, they were doing math and reading as well as their quieter peers. And another study showed that the brains of kids with attention deficit ultimately developed normally, just more slowly than their non-ADHD schoolmates. For more, check out the September 16th edition of "News Bytes of the Week"at

Well that's it for this edition of the weekly SciAm podcast. You can write to us and check out numerous features at our brand new redesigned Web site, including the community, theblog and the Daily Trivia featuring the answers to questions like, "What animal has the densest fur?" For Science Talk, the weekly podcast of Scientific American, I'm Steve Mirsky. Thanks for clicking on us.

I wouldn't leave you hanging. The animal with the densest fur is the chinchilla with about 60 hairs per follicle. Its favorite song is David Bowie's "Let's Dense."

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