New Frontier For Geeks: The Kitchen

In Cooking for Geeks: Real Science, Great Hacks, and Good Food, software engineer Jeff Potter discusses using the hacker mindset in the kitchen, from cooking salmon in the dishwasher to a warranty-voiding experiment on his oven to get the scorching temperatures necessary for perfect pizza crust.

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IRA FLATOW, host:

You're listening to SCIENCE FRIDAY. I'm Ira Flatow.

Well, the secret is out that not only do I like to eat, but I like to cook. And one of the joys of cooking for me is understanding and appreciating the chemistry that creates the foods we like to eat.

For many of us, though, even accomplished scientists and engineers, the science that happens in the kitchen is, well, a little mysterious, like the difference between using a stainless steel or a copper bowl to whip egg whites. How could that possibly matter? But it does. Copper bowls get much better results.

Or have you ever considered why we make brownies at a much lower temperature than we'd bake peanut butter cookies? I'll give you a hint: It has something to do with the melting point of sugar.

What about steaks? Why do most people like them medium rare and not cooked through like a brick? The secret is how the meat's protein reacts to heat.

These are just some of the science-y tips you can find in "Cooking for Geeks: Real Science, Great Hacks, and Good Food," a new book by my next guest. Jeff Potter is a software engineer and author of "Cooking for Geeks." He joins us here in our New York studios. Welcome to SCIENCE FRIDAY, Jeff.

Mr. JEFF POTTER (Author, "Cooking for Geeks: Real Science, Great Hacks, and Good Food"; Software Engineer): Thank you.

FLATOW: And thanks for bringing some of that food with you.

Mr. POTTER: You're welcome.

FLATOW: Let's - let me ask you first: Why do geeks need their own cookbook?

Mr. POTTER: Ah, good question. Well, what does it mean to be a geek? I should probably start there. For so many of us who are in the software and technology background, you know, it's very easy to think about what a geek means, but there's a much broader definition.

To me, a geek is anybody who's curious about the details about how things work. So that might not be a technology geek. That might be a car geek or somebody who's into sports. Just anybody who's curious about how things work, well, they would be a geek in some form.

So when it comes to the kitchen, somebody that has that sort of curiosity about the details needs something more than just a recipe. Recipes are just do this, do that, but they don't really tell you what's going on behind the instructions.

FLATOW: Exactly. That's - I must be a food geek. That's exactly how I feel.

(Soundbite of laughter)

FLATOW: I want to know when I'm mixing that stuff together, right, what's going on.

Mr. POTTER: Absolutely.

FLATOW: And not only that, I want to know how I can change the equipment I'm using, right?

Mr. POTTER: Yes, absolutely.

FLATOW: To work more - work better to exactly - and you talk all about this in your book.

Mr. POTTER: Yeah, and, you know, when it comes to somebody who thinks that way, putting things together, you really need to understand the basic fundamentals, not just have a series of instructions. Which is why, in the book, I spent a lot of time thinking about the food science.

And there are a couple of books out there that deal with, you know, either food science, and there's, well, lots of books that deal with recipes. But there are very few that are food science with recipes to illustrate and explain what the details actually mean.

FLATOW: If you like to cook, if you're a geek, our number is 1-800-989-8255. You can send us a tweet @scifri, @-S-C-I-F-R-I. Also go to our website, and we have a discussion going there at sciencefriday.com.

And we - let's kick this off with some food that you brought, okay?

Mr. POTTER: Okay. So I brought a little bit of stuff into the studio with me today. I'm actually going to start with the coolest geek toy ever.

FLATOW: What is that?

Mr. POTTER: Now, I'm holding what's called an infrared thermometer.

FLATOW: Wow, it's like a laser beam coming out of there.

Mr. POTTER: It has an infrared, well, it's got a little, you know, laser beam to help you sight it, but here, I'll hand it to you, and you can point it at things. And what it does is it tells you the surface temperature of whatever you're pointing it at.

FLATOW: Wow, this is geeky. 85... Right, I point it at you or the table or whatever.

Mr. POTTER: Sure. Now, when it comes to the kitchen, since so much of cooking is about the physical and chemical reactions that occur, and those reactions occur at different temperatures, understanding what temperature means in the kitchen is really important.

But it's not just, you know, the temperature that's important. There's also things like physiology and psychology of taste. So one thing I discuss in the book is about flavor combinations. And what I've brought in today is watermelon and feta. One's sweet, one's salty, but the two together actually is a surprisingly good combination.

FLATOW: All right, so you've got a big, nice tub of watermelon cut up. You can put it out there. And you - that's right. A lot of people like the salt and -the salty and the sweet combination.

Mr. POTTER: Yeah.

FLATOW: They follow one. Sometimes if you have popcorn, you say I've got to have some chocolate or something, right?

(Soundbite of laughter)

Mr. POTTER: Sure. And it turns out that there's a lot of different combinations, where when you're cooking something, not just thinking about the seasoning and the flavors but also thinking about the primary taste is a way of adjusting things.

So I've taken a little bit of the feta cheese and some balsamic vinegar and olive oil that I'm just going to pour on top of this.

FLATOW: Ooh, that looks good. So it's feta, olive oil, it's watermelon and some onions.

Mr. POTTER: And a little bit of red onion just to kind of spice it up and give it a little more interest. And I'll hand this bowl to you here, and you can kind of take a taste of these things together.

FLATOW: Talk amongst yourselves.

(Soundbite of laughter)

Mr. POTTER: Yes, I'm sorry that...

FLATOW: While I eat this. This is - let me get the one with, it's got vinegar on it. Mmm, that's good, very good. Want to try watermelon at the same time? Mmm, mmm.

Mr. POTTER: Yeah, well, the two together are really - it's a common enough thing that's been done out there, but to actually see the example. You know, cantaloupe and melon and things like prosciutto are commonly done, and again, it's a similar kind of combination of flavors.

So exploring kind of the gustatory system and the taste system and getting that kind of science background behind it means when you step into the kitchen...

FLATOW: It tastes good, and you know why it's happening.

Mr. POTTER: And you know why it's happening.

FLATOW: Let's talk about the temperature.

Mr. POTTER: Sure.

FLATOW: We mentioned in the beginning why you cook brownies at a certain temperature and why you cook other things. What's going on there?

Mr. POTTER: What's going on? Sugar - this actually took me a while to figure out and understand, my background being software engineering. Sugar caramelization and sugar melting are two different things entirely.

Sugar caramelizes starting around, well, somewhere between 320, 340. That means you get up to 380 and above, it starts to get really toasted and dark and burnt and bitter. But at 367 exactly, it happens to melt. It's a pure substance. So 365, it'll be solid; 370 it'll be melted.

And this is actually really clever because you can use this to calibrate your oven.

FLATOW: Oh, because all those thermometers really are so poor at having an accurate temperature.

Mr. POTTER: Right. We all know that water boils at 212, and, well, sugar melts at 367.

FLATOW: Exactly.

Mr. POTTER: So if you put it in an environment colder than that, it shouldn't melt. If you put it in something hotter than that, it should melt.

Now, if you're going to do this at home, keep in mind that just like taking an ice cube out of the freezer, it takes a little while for things to melt when they're only a few degrees up from their melting point. So you can take a little bit of sugar, put it in a bowl and toss it in your oven at 350, and it shouldn't melt even after an hour. And set it for 375, and it might take a half hour.

FLATOW: Right. What are some of the other key temperatures?

Mr. POTTER: Sure, so - well, the Maillard reaction, 310 degrees, is of course one of the most commonly...

FLATOW: The who?

Mr. POTTER: The Maillard reaction.

FLATOW: The Maillard reaction.

Mr. POTTER: And it's one that's most commonly known. It starts around 310. This is why we do our roasts at 325 or hotter. If you roast meat at 300, you're not going to get that nice, brown outside.

And then when it actually comes to the texture of meat and meat cooking itself, of course, that roast is not going to be internally at 310 degrees. It's going to be somewhere on the order of, eh, call it 140, 150, depending upon how you like your meat done. And that's based on the two temperatures that myosin and actin, which are two different proteins that occur in mammalian meat, denature.

And we just happen to prefer, texturally, when myosin denatures, which starts around 122.

FLATOW: Denature means the proteins unfold?

Mr. POTTER: Yeah, denature means that the actual structure of it changes, and as a process, as a result of that, it also changes its texture. And so, what scientists have found is that when you take meat and cook it at those temperatures where the myosin denatures, but the actin remains native, there's this great term - total textural preference - that they use in the literature.

FLATOW: TTP.

(Soundbite of laughter)

Mr. POTTER: I haven't seen it abbreviated.

FLATOW: I'll put it in there.

Mr. POTTER: Sure.

FLATOW: Yeah, total textural preference.

Mr. POTTER: And they find that we happen to like it between, you know, those two proteins, one being cooked and one being in its original form.

FLATOW: So that's the point where something goes from really rare to maybe a little bit...

Mr. POTTER: Right, and it's a time-at-temperature reaction. So it does take some time. It's not like, say, sugar, which melts instantly. It's a much more complicated thing.

FLATOW: 1-800-989-8255. Let's go to some geeks on the phone, Alex(ph) in Concord, Massachusetts. Hi, Alex.

ALEX (Caller): Hi.

FLATOW: Hi there. Go ahead.

ALEX: Okay, so I am a huge food geek, and currently I'm trying to major in food science, though I have more a comment that what you're talking about is more of food chemistry and molecular gastronomy under food science and that in food science, there is multiple different types.

For instance, the type I'm going into is I'm trying to go into food genetics. So...

FLATOW: Wait, wait, wait, wait, food genetics.

Mr. POTTER: Yeah, tell me more about this.

FLATOW: What's food genetics?

ALEX: It's - I guess that's what more of what, I could sum it up as, it's working with GMOs, like genetically modified organisms with plants. And my goal is, when I finally major in this, is to work on allergies.

FLATOW: I see. All right, Alex, thanks for calling, 1-800-989-8255. Let's see if we can get another geek on the line, but tell us before we do how you modified - was it a crockpot to become a super - I mean, I thought a crockpot is warm enough. You made it to cook even longer.

Mr. POTTER: Ah, so there's two different things here. One is the whole idea of using a crockpot for - well, there's a cooking technique called sous vide cooking, which is just a French term that means under vacuum, describes one step in the process.

When you hold food at certain temperatures, just like that sugar melting, you can cause certain proteins to denature and keep others native. So there's this whole movement of doing sous vide cooking where you take and cook meats, or fruits or vegetables, even, at precise temperatures to control what reactions occur. It's something that comes out of the lab.

FLATOW: Right.

Mr. POTTER: You can use a sous vide - you can make your own sous vide rig using a crockpot if you don't want to go and buy, you know, the thousand-dollar industrial, what they use in chemistry labs. But what you do with a crockpot is you basically get a thermocoupler, a thermo - a controller that reads that, and then interpose on the power supply to the crockpot to turn it on and off, to basically make a more precise crockpot.

FLATOW: So you have a temperature gauge in the crockpot...

Mr. POTTER: Yeah.

FLATOW: ...that reads - that senses, oh, time to turn the crockpot off for a bit.

Mr. POTTER: Exactly.

FLATOW: So it cycles it on and off.

Mr. POTTER: And all that's doing is making it more precise than the thermostat that's internally present in the crockpot. So, again, since so much of cooking is about time and temperature, collagen happens to hydrolyze and denature starting around somewhere in the order of, well, let's call 160. It depends upon some specifics we won't get into here. Crockpots, you know, are designed to allow for long, slow things to hydrolyze and denature in the collagen. The other thing I did, which I wasn't quite sure if you were getting towards, was the very high-heat cooking. I happen to have broken my oven door doing this.

FLATOW: Don't try - beep, beep, beep. Don't try this at home. Okay, go ahead, tell us what happened.

Mr. POTTER: So there's - one of the people I interviewed in the book - the book's got about two or three dozen interviews.

FLATOW: Right.

Mr. POTTER: One is a guy named Jeff Varasano down in Atlanta who clipped the lock off of his oven door, so he could open it while on cleaning cycle.

FLATOW: It gets really hot.

Mr. POTTER: It does.

FLATOW: In cleaning...

Mr. POTTER: And using this...

FLATOW: That's why it's locked.

Mr. POTTER: And using this geek toy, the infrared thermometer...

FLATOW: Right.

Mr. POTTER: ...you can find out that it runs about a thousand degrees.

FLATOW: Wow.

Mr. POTTER: Yeah.

FLATOW: And what can you do with a thousand-degree oven?

Mr. POTTER: You can cook a pizza in 45 seconds.

FLATOW: And only a geek would have thought of that.

(Soundbite of laughter)

FLATOW: And taken advantage of it. So you cracked open your oven door so that you could make the oven work while it was in the cleaning...

Mr. POTTER: Right.

FLATOW: ...self-cleaning phase.

Mr. POTTER: I replicated Jeff Varasano's work and find, in fact, it does make fantastic pizza. I broke my oven door in the process, and I now have, instead of glass, what's called PyroCeram. It's what the military used in the 1950s for missile nose cones. That's now what I've got for my oven door. It's a sheet of the stuff that is temperature-rated to much higher temperatures, but definitely not a thing to try at home.

FLATOW: No.

Mr. POTTER: Cooking your pizzas on a grill with a wood fire really is much easier, and gets just as hot.

FLATOW: 1-800-989-8255. Let's go to Jay in Manchester, New Hampshire. Hi, Jay.

JAY (Caller): Hello, hello.

FLATOW: Hi, there.

JAY: Hi. I'm enjoying the conversation very much. I've worked in restaurants for years, cook a lot at home. But I need to hear your guest say two words: Alton Brown.

Mr. POTTER: Alton Brown.

FLATOW: There, he did.

Mr. POTTER: Anybody that can make a six-year-old enjoy her vegetables has got a thumbs-up in my book.

(Soundbite of laughter)

JAY: Exactly. I just - give the devil his due. Alton Brown is a personal hero of mine.

Mr. POTTER: Absolutely.

JAY: And just give a little name recognition there, because he started the whole ball rolling.

Mr. POTTER: There's a lot of people, and he's done an amazing amount contributing towards the public's appreciation of food science. Of course, the other big name is Harold McGee, who's referenced in tome, "On Food & Cooking." It's a fabulous reference book.

FLATOW: All right, thanks for calling, Jay. 1-800-989-8255. We're talking about "Cooking for Geeks: Real Science, Great Hacks, Good Food" with Jeff Potter -very interesting book - on SCIENCE FRIDAY, from NPR.

One other interesting - there's so much interesting things to talk about. We've all eaten things with liquid smoke, a smoky flavor, but you actually say in "Cooking for Geeks" how to make the liquid smoke yourself at home.

Mr. POTTER: Yeah, it's...

FLATOW: How do you do that?

Mr. POTTER: How do you do that? It's a lot of work.

(Soundbite of laughter)

Mr. POTTER: It's a lot, a lot of work.

FLATOW: That shouldn't stop any geek from trying.

Mr. POTTER: Well, this is true. Basically, you need to take whatever your smoke sources - woodchips, hickory chips - and get them in a closed environment using chemistry equipment...

FLATOW: Right.

Mr. POTTER: ...to do it properly, and get them up to temperature and water-distill the smoke. You can kind of jokingly think of it as a water bong, where the water that's left over after doing the smoke filtration is your liquid smoke. And actually doing it this way, through the filtration, removes some of the potential carcinogens that either will precipitate out or float to the top, and you can skim off.

FLATOW: So the water goes through a little tube into some - the smoke goes through the tube...

Mr. POTTER: The smoke - that's right. (unintelligible) water.

FLATOW: ...(unintelligible).

Mr. POTTER: ...you do it in a closed vessel...

FLATOW: Right.

Mr. POTTER: ...and heat it, and the smoke generated from that will come up through your tubing into water, and you filter it through the water.

FLATOW: Is that how you make coke or something when you heat something in a closed vessel - I mean, the kind of carbon that comes out of it? Something like that?

Mr. POTTER: No idea.

FLATOW: And so then you can take the water, put it in a little jug, and flavor things with it.

Mr. POTTER: You can - although, again, it's pretty dilute at that point. And I turns out that - this surprised me, because a lot of people have opinions about chemicals in food and think of liquid smoke as a chemical. Now, of course, food is chemical. You know, whether...

FLATOW: Right.

Mr. POTTER: ...it be the watermelon and feta salad you had earlier, or whatever it is you buy at your grocery store, food is basically a chemical. And it turns out that liquid smoke is when - in its purest essence, is really nothing more than the smoke vapor distilled through water. And there's no chemical reaction occurring between something you're roasting or grilling and that smoke. So you can actually...

FLATOW: Right.

Mr. POTTER: ...deposit that smoky flavor on later, which means you can do fun things, like put that smoke essence into things that you wouldn't normally be able to smoke, such as, say, S'mores ice cream, which was actually - there's a group down here in New York called the Experimental Cuisine Collective that actually had a talk and a demo on this last year that I very much enjoyed. And there's a little bit of information about this in the book.

FLATOW: 1-800-989-8255. Talking with Jeff Potter, author of "Cooking for Geeks: Real Science, Great Hacks, Good Food." A couple of minutes before the break: a project that you would love to do, but you haven't got to time to do yet.

(Soundbite of laughter)

FLATOW: Geek project that if you had...

Mr. POTTER: Oh.

FLATOW: ...an infinite amount of money and you wanted to do it.

Mr. POTTER: I think if I had an infinite amount of money, one of the craziest things that I've wanted to do is - I don't know really where this idea came from, and my publishers will probably shudder - sorry, guys: make a gin and tonic while skydiving.

FLATOW: Make it in - while you're - are you a skydiver?

Mr. POTTER: I'm never actually done any skydiving, no.

FLATOW: I'm willing to bet you it's been done.

(Soundbite of laughter)

Mr. POTTER: I'm sure. But I haven't seen it. And, you know, it sounds kind of crazy and fun but, heck, why not?

FLATOW: Well, you need to make it a kit, I guess. You know, geeks are - yeah.

Mr. POTTER: The other geek dream would be actually to eat at elBulli. This is one of the preeminent restaurants in Spain. Ferran Adria, who's well-known for...

FLATOW: Mm-hmm.

Mr. POTTER: ...combining science and food to produce new and interesting dishes...

FLATOW: Uh-huh.

Mr. POTTER: ...in a true art fashion.

FLATOW: Is there a device that - like a cooking, like a new kind of Cuisinart or something that you would love to have that doesn't exist?

Mr. POTTER: Oh.

FLATOW: That - think of something original. You don't have to think now. We're going to go to the break.

Mr. POTTER: Okay.

FLATOW: But think - now, everybody, at 1-800-989-8255. We're talking with geeks about food and equipment. What piece of equipment should - could we all put our heads - we could crowdsource this.

Mr. POTTER: This? Yeah, absolutely.

FLATOW: You could tweet us @scifri, @S-C-I-F-R-I. What piece of equipment do you need to have in your kitchen, besides that oven that cooks the pizza in 40 seconds, that we don't have now? And maybe we can think about it, building it together. 1-800-989-8255. Tweet: @scifri, talking with Jeff Potter, author of "Cooking for Geeks." We'll be right back after this short break.

(Soundbite of music)

FLATOW: You're listening to SCIENCE FRIDAY, from NPR. I'm Ira Flatow. We're talking this hour about "Cooking for Geeks: Real Science, Great Hacks, Good Food," a new book out by software engineer Jeff Potter. And while we're talking about cooking and about different kinds of tastes and flavors, I'd like to bring on another guest. If you can't get enough of - we talked about it - the spicy Sriracha sauce, or you'd like to eat whole jalapenos for a snack, you might be getting a little unexpected benefit along with the burn.

Here to talk about it is my guest, William Sessa, director of the Vascular Biology and Therapeutics Program at Yale University's School of Medicine in New Haven. He's also professor of pharmacology there. And he joins us over the phone. Welcome to SCIENCE FRIDAY, Dr. Sessa.

Dr. WILLIAM SESSA (Director, Vascular Biology and Therapeutics Program, Yale University School of Medicine): Well, thank you very much. My pleasure.

FLATOW: You're welcome. You have a new study out that says that eating these hot chili peppers lowers blood pressure, at least in rats, mice?

Dr. SESSA: Yeah. So basically - it actually was not our study. I was - I wrote the commentary on the study. And, basically, it was a surprising finding, because most people believe that, obviously, hot chili peppers will cause pain, the sensation of pain, whereas in this study, when they give it to animals chronically, particularly animals that have high blood pressure, the active ingredient actually lowered blood pressure in the animals. So it's quite remarkable.

FLATOW: Is there any evidence in our popular culture that people who eat hot, spicy things do have lower blood pressure?

Dr. SESSA: Well, you know, in the United States, I'm not aware of such epidemiological literature. But there are some studies, I believe, in certain parts of Asia where certain populations do eat a lot of foods containing hot chili peppers, and they tend to have less cardiovascular disease. Now, this is truly anecdotal at this point, but it's sort of provocative.

FLATOW: And what is the mechanism for it working?

Dr. SESSA: Yeah. So I'd say probably about 15 years ago now, several scientists identified sort of receptors or proteins that bind natural products. And so the major natural product from chili peppers is a chemical called capsaicin. And so what was shown in this paper was that capsaicin, by binding to its receptor, would activate a pathway that's known to lower blood pressure in humans, as well as in animals, and this is primarily the nitric oxide system.

You have - may have heard of this system. This system resulted in Nobel Prize to three investigators in 1998. Nitric oxide is a system that - your body makes this gas that keeps blood vessels dilated and lowers blood pressure. So they showed, basically, that the active ingredient from the chili pepper activated this system in your body to lower blood pressure.

FLATOW: Mm-hmm. I think it's how Viagra and things like that work, also.

Dr. SESSA: Absolutely. That's correct.

FLATOW: It was Carl Djerassi, one of the Nobel winners who has been in our program to talk about it. So you know that this might be the mechanism for it working, but we don't know if it really works in people. And so far, this study - these studies you cite are done in laboratory animals?

Dr. SESSA: Yes. So some of the early studies in the paper, we're using human cells, showing that this pathway's operational. But then to show that this was relevant in intact system, they went to hypertensive rats.

FLATOW: Mm-hmm.

Dr. SESSA: So you're correct. There is no evidence in humans that this actually will work, as of yet.

FLATOW: But, you know, capsaicin, it causes a lot of pain. You eat some of those chili peppers, you're not going to want to eat them again. How can - how could - can some people eat so many chili peppers?

Dr. SESSA: Absolutely. No, that's a very good question, because it's very difficulty to imagine that your nerve endings respond to this to give you the sensation of pain, but at the same time, your blood vessels will sense this and it will increase blood flow. Now, we know that during the sensation of pain, there's increases in blood flow, so nature has co-opted this dual mechanism to actually do both. But you can imagine a system where if you're able to actually hit the cardiovascular receptor but not the nerve receptor, perhaps you can have a beneficial effect without the heat, so to speak.

FLATOW: Hmm. And I guess for people who constantly eat chili peppers, they must get acclimated to it.

(Soundbite of laughter)

Dr. SESSA: Yeah. Well, what happens is that that even when - in experimental models, when they give this capsaicin, which is the active ingredient, chronically, you do become desensitized to it, eventually.

FLATOW: Mm-hmm.

Dr. SESSA: Yeah.

FLATOW: I'm sitting here with Jeff Potter, author of "Cooking for Geeks." Do you have anything about - anecdotal stuff about chili peppers?

Mr. POTTER: I've got one - one good one. One of the interviews I did was with a nutritional researcher from Cornell, and she told me this wonderful story. She had said that the neurotransmitter - I guess she said it was called substance P. I think...

Dr. SESSA: Yes.

Mr. POTTER: ...P stood for pain, or I guess - well, that's what I had heard.

FLATOW: Mm-hmm.

Mr. POTTER: She had said that it deplenishes over, you know, several weeks' exposure to it. And after, you know, not being exposed to it for a couple of weeks, it would start to replenish and come back up in its levels. And she was saying, in Cornell, in the mid '80s, she would have students come over from India, where they were used to very spicy food with a lot of capsaicin. And they would start eating the dorm food that, at that time, didn't have so much capsaicin - chili peppers, whatnot - in it. And then they would go back home and they'd eat their mothers' cooking.

(Soundbite of laughter)

Mr. POTTER: Ah, the laughter there. Yes, exactly, because they couldn't stand it because their substance P levels had replenished.

Dr. SASSA: Yes.

Mr. POTTER: And they would go, this is so hot, I can't eat it. And their mothers would say, what has America done to you? They've corrupted you.

(Soundbite of laughter)

Dr. SASSA: That's funny.

FLATOW: That's funny. Well, Dr. Sassa, I want to thank you for taking time to be with us today.

Dr. SASSA: Oh, it's a pleasure.

FLATOW: Thanks for filling us in on that research.

Dr. SASSA: Thank you very much.

FLATOW: William Sassa is director of the vascular biology and therapeutics program at Yale University School of Medicine in New Haven. And he's professor of pharmacology there. Our number: 1-800-989-8255. Still with me is Jeff Potter, author of "Cooking for Geeks: Real Science, Great Hacks, Good Food," good book.

Mr. POTTER: Thank you.

FLATOW: Jeff, really interesting read. Tell us a little about one of the things that you mentioned in the book is the constant confusion that even good cooks, chefs, have over baking powder and baking soda.

Mr. POTTER: Ah, yes.

FLATOW: What's the difference?

Mr. POTTER: The difference. Well, baking soda itself is just a bicarbonate. It's, you know, a single thing. Whereas baking powder is a self-contained system of both bicarbonates and an acid that will react with it.

FLATOW: Mm-hmm.

Mr. POTTER: So with baking soda, you have to put it into a food that has enough acid to react with it. Whereas baking powder is pretty much just, you know, add water and heat and you've got air.

FLATOW: Right.

Mr. POTTER: And what surprised me was, in two of the interviews with people I will - shall remain nameless, but they're both in the public eye for, you know, explaining and - explaining - you know, doing recipes and that sort of thing. Both of them said they were confused about how to kind of tell which one to use and when. And, you know...

FLATOW: And they were - that's what they did for a living. So they...

Mr. POTTER: Yeah. It is a little bit complicated sometimes.

FLATOW: Yeah.

Mr. POTTER: But it basically comes down to, you know, the food you're cooking. Since we're using things like baking powders and baking sodas to generate air, to give lift to foods that we bake, especially, you basically use baking soda to the point where there's not enough acids left for it to react with. And if you still need more leavening, you then switch to using baking powder, which is why some things will call for both baking soda and baking powder.

FLATOW: I see.

Mr. POTTER: This is why if you look at a recipe for buttermilk pancakes, the buttermilk itself has got a fair amount of acid in it, so the recipe will call for baking soda, but a more traditional pancake recipe will just call for baking powder.

FLATOW: Well, we asked our friends out there - and tweets are coming in about the - what machine they would like to have in their kitchen. And I got a couple of very interesting answers.

Mr. POTTER: I'm ready.

FLATOW: And one that I had thought about, one - the couple - first, one answer is - R.Contact(ph) wrote, that we need an instant freezer.

Mr. POTTER: An instant freezer.

FLATOW: In other words, it's like if you have a microwave oven that instantly heats things up, can we find the opposite of that...

Mr. POTTER: You know...

FLATOW: ...and instantly freezes - freeze dries something?

Mr. POTTER: You can certainly use liquid nitrogen for that, if you happen to have some and know how to use it and are safe and careful. Industrial processors do have blast freezers that they use for freezing things like string beans or broccoli that are - right after they're picked from harvest.

FLATOW: Mm-hmm.

Mr. POTTER: Obviously, if you freeze things more quickly, the water crystals inside the structure of whatever you're freezing will be smaller so less likely to make cellular damage, so better texture.

FLATOW: Right. And another suggestion was something I had seen, myself, and wondered if you could buy this for your kitchen, if you'd need one. And that is the kitchen equivalent of the stir plate with the stir bar. And you seen in the labs, you know?

Mr. POTTER: Oh, yeah.

FLATOW: It sits on a little platform and there's a metal piece that's rotating inside the beaker.

Mr. POTTER: Yeah. You know...

FLATOW: Wouldn't we like to have that?

Mr. POTTER: That actually sounds kind of useful.

FLATOW: Mixing drinks or whatever for ourselves, a kitchen equivalent?

Mr. POTTER: I think that is vaguely somewhere in the back of my head...

FLATOW: Yeah? Think so?

Mr. POTTER: ...as a memory of something that does that for stews and - like kind of clamp on on top of the, you know, goes over a pot and it's electric motor that does that.

FLATOW: Right. Right.

Mr. POTTER: But...

FLATOW: Well, somebody, I'm sure.

Mr. POTTER: Somebody out there can...

FLATOW: Somebody will tell us of that. The other thing that - a gadget that gets very little mention but is still very useful these days, is the pressure cooker, right? And the other one is the coffee percolator. I guess I'm watching "Mad Men" too much to remind myself of these old things that I had as a kid. There's no real way to improve on a pressure cooker, would there? I guess you could make it get hotter inside so that you get more pressure but that...

Mr. POTTER: Yeah, but...

FLATOW: Well, you don't want do that. It'll take off for the moon. You don't want that.

Mr. POTTER: Yeah, at some point, the reactions that you have occurring in the food, you know, are occurring; you either are above the reaction temperature or you're not. I mean, okay, yeah, there's time and temperature. That does matter. But it seems like a pressure cookers probably get high enough pressure for most purposes.

FLATOW: Mm-hmm. Let's see if we can get a phone caller. Lavern in Napa Valley, California, wants to know - hi, come on.

Mr. LAVERN MAC(ph)(Caller): Yeah, hi.

FLATOW: Give me some question. Hi. How are you?

Mr. MAC: Lavern Mac. I've been a geek for 85 years, which is also my age. I think I was born with a hand full of electrons. And the thing about this infrared thermometer really fascinates it. Is that actually something that's on the market today?

Mr. POTTER: Yes, it is. And in fact, they're relatively cheap. Mine's about $50.

Mr. MAC: No kidding.

Mr. POTTER: It works just by looking - you know, it's basically got a single pixel camera if you think of it that way. Think about something like coal in a fire and how it's glowing. You can see that and...

Mr. MAC: Could you throw a brand name at me so I could trace that?

Mr. POTTER: You know, I think that the most common brand is probably the meters made by Fluke. The one I have here says...

Mr. MAC: Fluke is an instrument manufacturer, as I recall.

FLATOW: Right.

Mr. POTTER: Yeah. The one I...

FLATOW: I'm sure if you just Google it, you'll find a million of them.

Mr. POTTER: Yeah. Infrared thermometer is what I would search for online.

FLATOW: Good luck.

Mr. MAC: Yeah.

FLATOW: You know, and what that would be good for, you know, when they say it's hot enough day to fry an egg on...

Mr. POTTER: You know, The New York Times did a piece on this about a month ago, and I was thinking to myself as I was reading through it, they didn't know the actual temperature of the surface. Eggs don't begin to cook and denature until 142, 144 Fahrenheit. If you had an IR thermometer, you could go find the perfect spot to fry your egg on the sidewalk.

FLATOW: Right. And the perfect car hood.

(Soundbite of laughter)

FLATOW: A much better spot if you're going to actually eat the eggs.

Mr. POTTER: Well, if The New York Times wants to do a revised version, I can lend them my IR thermometer.

FLATOW: Mm-hmm. 1-800-989-8255. Let's see if we can get another call. Steve(ph) in Vancouver. Hi, Steve.

STEVE: Yeah. Hi there. I just wanted to make a comment. I'm an appliance repairman and I don't want too many service calls on this. On the 500 degrees -or the 350 degrees in the oven - portion with the sugar. Ovens have radiant temperature, so they go up and down as they try and do the heating. So we take an average of a high temp and a low temp in the oven, so we get 350.

Mr. POTTER: Yes, absolutely. They do cycle up and down. And I've actually found that by putting something like a pizza stone in your oven, you can help regulate that heat and get a much more even heat. I've metered mine...

STEVE: Right.

Mr. POTTER: ...at home and it actually - mine is an electric one. And with the pizza stone directly above the heating element on the bottom, it blocks any radiant heat directly. And I find that mine only cycles by about a degree. If you're going to do the sugar thing, which really - use an oven thermometer, it's much better.

STEVE: Yeah.

Mr. POTTER: But if you're going to do the sugar thing, keep in mind that it -your oven obviously does cycle up and down, which is why you want to, you know, leave 10 or 15 degree leeway on each side.

STEVE: Mm-hmm. It does. And the old thermostats had a higher variance. The computer ovens are a lot closer, right on, but the old thermostats had a really high variance. So you would melt your sugar and then you'd call me and I'd make lots of money off of that. So...

FLATOW: There you go. Keep the electricity.

STEVE: And I had to let somebody know about that.

FLATOW: There you go. Thanks for calling. Have a good weekend.

1-800-989-8255. We're talking about science - "Cooking for Geeks - Real Science, Great Hacks, Good Food." Jeff Potter is here on SCIENCE FRIDAY from NPR. I'm Ira Flatow.

We actually got a response on how you can make that stirring equipment.

Mr. POTTER: Hmm.

FLATOW: Now, let's see, I got it down there. Homebrewers - it's says on my tweet, and it comes from PB Haas(ph). Homebrewers use rare earth magnets glued to computer fans.

(Soundbite of laughter)

FLATOW: To make their own stir plates.

Mr. POTTER: That's very clever.

FLATOW: Can you picture that?

Mr. POTTER: Yeah.

FLATOW: Yeah? A computer fan circulating around, and it serves as a - hmm. I guess you got to wash it off a little before... And now there are, Lord knows, surplus of all kinds of computer fans. 1-800-989-8255. Let's see if we can get a quick phone call in here from Benoir(ph) in Los Altos. Hi.

BENOIR (Caller): Yes. Good morning. I always thought that using some of those low-cost laser engraver to do patterning on top of steak would be something kind of interesting to do. You could really do custom logo or custom grill pattern on steak and be able to really control that with a computer. And I would assume that those laser engravers are powerful enough to do a nice burn layer onto the top of your steak or vegetables.

Mr. POTTER: Yes, that actually reminds me of two different things. One is that some students at the MIT Media Lab, some number of years ago, actually did exactly that, where they were basically printing onto food. And the second thing that comes to mind is actually there's two individuals who are - Lenore and Windell of Evil Mad Science - who have actually used a laser cutter to etch in an Apple logo on top of the pie pastry for an apple pie, making an Apple apple pie.

FLATOW: Wow. And you know, now that you - now that we have ink jet printers and you - and people are putting all kinds of stuff in the container where the ink used to be. You can print anything, right, on a piece of paper - not just a printed circuit, but something edible.

Mr. POTTER: Mm-hmm. Nori, seaweed.

FLATOW: Right - good idea.

Mr. POTTER: It's been done.

FLATOW: It's been done.

Mr. POTTER: It's amazing how much stuff in food has been done.

(Soundbite of laughter)

FLATOW: Well, you know, you see these birthday cakes with the pictures on top...

Mr. POTTER: Yeah.

FLATOW: ...that must have gone through...

Mr. POTTER: And then you have things like fail cake, where, you know, somebody says to the person icing the cake, you know, make sure to add such and such and they actually ice the cake with those words, as opposed to just knowing them as instructions. There's a website out there, that I don't remember the URL of, but it's photographs of failed cakes, the, kind of the logical extension of that.

FLATOW: So what's next for you? What - where are you going what no other person dares to go.

(Soundbite of laughter)

Mr. POTTER: That is a good question. I don't know. Right now, I'm just having a lot of fun with this book and getting it out there in front of the people and, you know, really hoping that people get a chance to get into the kitchen...

FLATOW: Mm-hmm.

Mr. POTTER: ...try new things, not be so afraid of burning the dinner and, you know, go experiment and play.

FLATOW: Mm-hmm. And summertime is a great time.

Mr. POTTER: Oh, absolutely.

FLATOW: Especially since you're outdoors and if you make a mistake, easier to clean up, right?

Mr. POTTER: Absolutely.

FLATOW: We, you know, and if you're barbecuing and you want to get that that char on top and bottom, what's the best temperature? Do you need a meat thermometer to do that well?

Mr. POTTER: Well, we're just talking about like charring a hamburger?

FLATOW: Yeah.

Mr. POTTER: This gets into the whole food safety thing.

FLATOW: Right.

Mr. POTTER: When it comes to things like steaks - well, when it comes to food in general, cooking them at a high enough temperature to kill any pathogens that might be in the surface is really important. But things like steak, we're not so worried about the middle of that steak when it's what's called whole muscle intact. But things like hamburgers are ground up, where there's all outside.

FLATOW: So you better cook it.

Mr. POTTER: So you do you want to cook it? You know, from a food safety point of view, you want to get it up to at least, you know, the USDA-recommended temperature, which offhand, I think, is 160 for an instant kill.

FLATOW: Mm-hmm. And so there - and that's what we were hoping for there.

Thank you. Thank you, Jeff Potter. Author of "Cooking for Geeks: Real Science, Great Hacks, Good Food," good book.

Mr. POTTER: Thank you.

FLATOW: Thanks for coming on with us today.

Mr. POTTER: My pleasure.

FLATOW: So he's a software engineer, and you could get the book at Amazon and it's in Kindle and all kinds of forms like that. All right, thanks again.

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