Food Failures: Too Hot In The Kitchen? Try No-Heat Cooking

IRA FLATOW: Summer is here. And if it’s not too darn hot today, you know it’s bound to be again soon some time, because as the mercury rises, what’s the last thing you want to do? It’s hot. It’s hot in the kitchen. You don’t want to spend your afternoons next to a hot oven with four pots boiling on a stove. Maybe you don’t even have the space for barbecuing. So what’s the solution?

Well, for some it’s a lot more salads and sandwiches, and maybe ice cream for dinner. But what if you could cook up something tasty without using heat? Now, it’s a bit more interesting than, maybe, just having ice cream. There is a trick. There are lots of tricks we’re going to talk about on how to cook without the heat. Maybe using a bit of lime juice, a lot of salt, or other tricks of science.

Well, you interested? It’s time for a special no heat edition of our food failures series. And if you want your tricks, too– do you have a favorite no heat cooking technique or recipe? We want to hear about it. You can give us a call, 844-724-8255. 844-SCI-TALK. You can also tweet us at SciFri.

I have a tray full of wonderful, cold, delicious-looking food here. And sitting across from me is Jeff Potter, author of Cooking for Geeks– Real Science, Great Hacks, and Good Food. As I say, he’s here in our New York studios. Welcome back to Science Friday, Jeff.

JEFF POTTER: Thanks for having me, Ira.

IRA FLATOW: You can cook without heat.

JEFF POTTER: Well, depends on your definition of cook. But if you consider it preparing food, yes. And what I brought you today is probably the strangest lunch of all– salmon gravlax, some beef jerky, ceviche, and salt preserved lemons. Well, doesn’t exactly go all together by itself, but all great examples of things we can do.

IRA FLATOW: A lot of good grazing, here. Now, let’s talk first about why heat is such a crucial part of cooking in the first place.

JEFF POTTER: Well, there’s really two reasons that we cook food, in terms of putting heat on it. One is for textural changes and things that make the food more delicious. So think about that steak that’s seared and has those nice, brown [? mired ?] reaction aromas. But the second reason is around the safety aspects. And heat really turns out to be a fantastic way to kill those pathogens that might make you sick.

IRA FLATOW: Right, yeah, it makes it easier to digest. But you have to kill off the baddies.

[LAUGHTER]

JEFF POTTER: Right.

IRA FLATOW: If we’re looking to eat without heat, what do we need to do to make it, then, safe?

JEFF POTTER: So if we’re talking about the pathogens and the aspect of safety, pathogens themselves have a couple of different variables that are important for them to be able to thrive and survive. There’s this lovely acronym– FAT TOM– where each letter stands for something that is important for microbial growth.

I won’t rattle through all of them, but the lemon and lime juice is the A, and the fat, which is acidity. So the pH range is really important. And then there’s things like oxygen. Obviously, bacteria and microbes have to be able to go through respiration. Or, in some cases, anaerobic without it.

And then there’s also things like– the M in FAT TOM, actually– moisture. Another really important concept. And that’s where our beef jerky comes into play.

IRA FLATOW: All right, we want to hear from you. If you’d like to take part in heatless cooking, 844-724-8255. This is Science Friday from PRI– Public Radio International. Talking with Jeff Potter, author of Cooking for Geeks.

OK, let’s start with acidity. Can I dunk my burger in vinegar?

[LAUGHTER]

Make it safe to eat?

JEFF POTTER: I don’t know about dunking a burger in– well, hamburgers are ground meat. And the issue there is that, essentially, it’s all outside. So when we’re talking about beef, the issue there is any surface contamination that might come up during slaughtering. And when you grind it, that surface contamination– well, hamburger’s all ground beef.

So if you were to dunk it in vinegar or lime juice, you’re only actually coating the outside at that point. But if you took something that was not ground, where the surface had had some contamination and you dipped that into something very acidic, that would take care of surface contamination.

And with something like whole muscle intact steak, that interior is considered generally sterile, so that actually would take care of it. And there are some dishes in some cultures where you take beef and you actually marinate them in something that’s very acidic.

IRA FLATOW: Give me an example. You brought something with you that’s been cooked with acid.

JEFF POTTER: Well, in this case, the scallops are in lime juice. So these scallops are previously frozen, which means anything that might be in the interior, in terms of parasites, would be killed by the freezing process. And then the outside has been soaked in lime juice, in this case.

Scallops actually take quite a long time to really do much of anything, so a couple of hours. Other kinds of fish– saltwater fish actually can go faster. 30 minutes, maybe an hour. So in this case, it’s really about the food item. What pathogens might be present on that food item? And then what technique can we use to render those pathogens mostly safe?

IRA FLATOW: So by definition– I’m looking at it, and it looks like a raw scallop. In terms of, it’s not being cooked on a flame.

JEFF POTTER: It’s not been cooked with heat. Now, this goes into the definition.

IRA FLATOW: Should I give it a try?

JEFF POTTER: Yeah, go for it. This gets into the definition of, what does cooked mean? And that’s more of a linguistic question, less of a science one. In this case, the acidants are taking– and that’s very acidic, it’s just straight up lime juice. I didn’t add any cilantro or onions as I might normally.

IRA FLATOW: Delicious.

JEFF POTTER: So in this case, you need about 15% of lime juice or lemon juice or vinegar by weight to make sure you have a sufficiently acidic environment. But yeah, it’s basically taking the proteins on the outside and denaturing them, changing the way they are structured. And that, of course, would also denature any bacteria that might be on the outside.

IRA FLATOW: And of course, I make pickles at home. But I ferment the pickles. Is that sort of cooking them, fermentation?

JEFF POTTER: Yeah, sure, definitely. In that case, what you’re doing is you’re introducing a particular– not a pathogen, but a particular bacteria, and letting it go to town. And that particular strain is going to essentially prevent other things from coming in and taking over. Well, actually, that’s a fascinating question for somebody in the fungal area, in terms of the science of that.

IRA FLATOW: That’s something that’s going on anaerobically, because it has to be under the brine there. So it’s an anaerobe. So many things to talk– I want to get to all the food on the tray here, so I’m not going to start, because we have to go to a break.

But we’re talking with Jeff Potter, author of Cooking for Geeks. If you have a recipe or something you’d like to suggest that you make without using a flame or very low cooking, give us a call. Our number is 844-724-8255. You can also tweet us at SciFri. We’ll be right back after this break, stay with us.

This is Science Friday. I’m Ira Flatow. We’re talking about ways to cook your food without using heat, or a very tiny amount of heat. It’s a sweaty, mid-summer edition of food failures, where we try to keep the kitchen as livable as we can. If it’s not hot where you are now, you will thank us later.

Summers are getting hotter. My guest is Jeff Potter, author of Cooking for Geeks, and I just finished sampling something that was soaked in lime juice for a while. It was delicious!

JEFF POTTER: Thank you.

IRA FLATOW: And so that’s very acidic. What about going in the other direction, something very alkaline?

JEFF POTTER: So we don’t have too many foods that really use things that are particularly basic. Most foods happen to basically be acidic. The few cases I could really find were things that involved lye.

So century eggs use lye to actually pull up the pH to 9 to 12– that high, actually. And then you’ve got things like– there’s this Norwegian fish. I can never say the name. “Luttfisk?”

IRA FLATOW: Lutefisk.

JEFF POTTER: Lutefisk.

IRA FLATOW: Oh, I spent a lot of time in Minnesota. I think it’s buried in the ground. It’s actually treated with lye, absolutely. And I’ve had lutefisk. And let me be kind about it and say it’s an acquired taste.

JEFF POTTER: There are a couple of dishes around the world that are acquired. Iceland is famous for its buried shark. And I would say between eating something like buried shark or lutefisk versus starving, I would probably take the food, even if it’s got strange things.

Lutefisk was really funny. I was trying to dig into more about what happens to the science. We don’t know so much. But one thing I did find was that in the Wisconsin statutes, they specifically define toxic substances, and they exclude lutefisk. It’s actually in their list.

IRA FLATOW: Wow. Well, let me tell you. We have a big audience in Minnesota. We’re going to hear today–

JEFF POTTER: I want to know–

IRA FLATOW: We’re going to hear, before–

JEFF POTTER: How did that writer get added? In the regulation industry, billions in safety, it’s down there. It says lutefisk.

IRA FLATOW: We will, I tell you, and we’re going to hear it today. And many times, maybe. Let’s go to Ryan in Provo, Utah. Hi, Ryan.

JEFF POTTER: Hi.

IRA FLATOW: Hi there, go ahead.

RYAN: Yeah, I wanted to ask Jeff if he’s looked into cured egg yolks?

JEFF POTTER: I actually have a cured egg yolk sitting in my fridge right now at home that I forgot to bring in for this.

IRA FLATOW: What is a cured egg yolk, for we novices?

JEFF POTTER: So you can take an egg yolk and basically drop it into salt– surround it in salt. Get a cup, put a half inch of salt in the bottom, put the egg yolk in. Cover it with another half inch of salt, let that sit in your fridge for about a week or so, and you can let it go two weeks. And you’ll get something which is cured yolk.

The salt’s drawing out a lot of the moisture, reducing the available moisture in the egg from a pathological point of view. But it also changes the texture, changes the flavors. I’m told at two weeks in you get something that’s vaguely like Parmesan, strangely.

IRA FLATOW: Right, Ryan do you have some?

RYAN: Yeah we experimented with that at a restaurant where I cook, and he’s right on saying it’s like a Parmesan where you can shave it over food.

JEFF POTTER: I’ve had it that way, it’s fantastic.

RYAN: We threw in some aromatics– sorry, go ahead.

JEFF POTTER: I was going to say, I’ve had it that way and it’s fantastic. Now, you’re starting to say aromatics, what else are you doing with it? Because I don’t know what to do with the egg yolk I’ve got at home besides shave it slightly on the salad.

RYAN: Yeah, that’s why I was curious what you had been doing. We threw in some thyme and rosemary. And I had read about it in a book, and I was wanting to learn more, because the chefs I worked with hadn’t really done much with it. But it had a really interesting flavor. Just enriched and concentrated– that yolk– buttery, umami flavor.

IRA FLATOW: Wow.

JEFF POTTER: That makes a lot of sense.

IRA FLATOW: Yeah, Jeff taking notes here.

[LAUGHTER]

JEFF POTTER: Third edition, right?

IRA FLATOW: Good luck, Ryan, and thanks for sharing that hint for us. A cured egg– I never heard of that.

JEFF POTTER: It’s really cool, actually. There’s something about the concentration process that changes the flavors. Not just concentrates them, but it actually– from what I understand– does something to allow additional new flavor compounds to come about.

IRA FLATOW: OK, let’s go back to my tray here, because I want to get to some of these tasty-looking things. There’s beef jerky there. What does that symbolize?

JEFF POTTER: Well, when I said FAT TOM earlier, that’s the M in moisture. And with beef jerky, what we’re doing is removing as much moisture as possible to get what’s called the water activity, which is a measure of the amount of available moisture– to get that water activity down low enough. And it’s basically a way of preserving. Where there’s not water available for microbes to grow, well, then, they don’t grow.

IRA FLATOW: I grossed out a lot of people last week chewing, so I’m not going to do that again.

[LAUGHTER]

JEFF POTTER: So there’s two pieces there.

IRA FLATOW: Yeah, I just had a piece. I turned the mic off. It was really good. It’s salty, right? Is that part of the dehydration process?

JEFF POTTER: Well, salt helps the proteins in the meat tissue bond to more of the water. So when I talk about moisture and water activity, it’s really about how much water is available. And the salt there is allowing the proteins to hold onto more of the moisture, making it not available. So it is related. It’s not necessarily a specific salinity that’s required, but it helps.

IRA FLATOW: It’s good. And is dehydrating a common way of storing food, or preparing it if you’re not heating it?

JEFF POTTER: Well, it depends on what you think of in terms of foods that are dehydrated. Are spices dehydrated? They certainly are. Almost anybody who is a regular cook has got something at home in their cupboard that’s dehydrated in that sense. Depends on where you are in the world, and culture as well.

IRA FLATOW: Well, actually, we have on our website– at sciencefriday.com/jerky– we have more tips and tricks on the beef jerky from Cooking for Geeks on our website sciencefriday.com/jerky.

Lots of people calling in with other kinds of advice, other tips. Let’s see if we can get one. Charles in New Haven, hi, welcome to Science Friday!

CHARLES: Hey, how are you doing today?

IRA FLATOW: Hey there, go ahead!

CHARLES: So I have a bit of a funny story, and then it turns into a better recipe from there.

IRA FLATOW: Go for it.

CHARLES: The funny story is back in undergrad– my background is a chemistry major– we used to have what we called lab sprouts. It’s a terrible idea, but was always fun at parties.

And what lab sprouts was, was we take a gallon Ziploc bag, we’d drop all the fixings you have for Brussels sprouts– the sprouts themselves and whatever you wanted to them– and then we’d leave them soaking for a long time in lab-grade acetic acid. And for those of you that aren’t quite familiar with what acetic acid is, all your vinegar is 5% acetic acid by weight. So it’s a concentrated, basically, form of vinegar. We just let it stew in that for a long, long time.

IRA FLATOW: How long is long?

JEFF POTTER: Yeah.

IRA FLATOW: I mean, what is that, a week? Is that a year?

JEFF POTTER: Ira and I are looking at each other here going, OK. What’s long?

CHARLES: I think we once had a three month-er. We let it sit for a while.

JEFF POTTER: Now, OK, I’m now curious. What does this do to the Brussels sprouts? Because that seems intense. And, now, we’re talking a glacial acetic acid?

CHARLES: Yep, 100%. Not 100%–

[INTERPOSING VOICES]

CHARLES: Not 100%, but yeah–

JEFF POTTER: Really close. You can’t actually quite get to 100.

CHARLES: Yeah, no.

JEFF POTTER: So what did it taste like? When you take it out after three months, what does it taste like?

CHARLES: Sour’s the wrong word for it, but it is the chemical equivalent of a sour punch in the face.

JEFF POTTER: So it was more sour than sour?

CHARLES: Yes, exactly. It’s like if you got sour down to just what the chemical equivalent of it was, that’s what it tastes like.

JEFF POTTER: I’m going to go on record here and suggest this does not sound like a good practice for other listeners to try.

IRA FLATOW: Don’t try this at home.

JEFF POTTER: You had mentioned you had a recipe or something that came out of this.

CHARLES: Yeah, so I don’t know if you guys are at all familiar with what a switchel is.

IRA FLATOW: No.

JEFF POTTER: No.

CHARLES: A switchel is a process where you take a sugared syrup and you take a vinegar– frequently it’s apple cider syrup and apple cider vinegar– and you make it a very concentrated vinegar. So it is high in that acetic acid. And you basically mix it together and let it sit for a while until it becomes this incredibly potent construct.

And then once you have that, you can do a lot of stuff with it. You can dilute it to make a base for drinks. You can turn it into an oil and vinegar salad dressing, or you can stew vegetables in it. You can add just a little bit of heat, or you can just add herbs, spices, salt, and you can let the flavor soak into it. And it’s much less a novelty party trick than lab sprouts were.

JEFF POTTER: I’ll have to look that up. It makes me think of shrubs and drinks– concentrated.

IRA FLATOW: Well, I see you’ve put your chemistry background to good use– making good food. So thank you for–

CHARLES: I appreciate that.

IRA FLATOW: Thank you for sharing that with us. Have a good weekend. Yeah, so there’s this interesting stuff going on.

JEFF POTTER: It never ceases to amaze me, the things that people are willing to Guinea pig on themselves when it comes to things they’ll cook in their kitchen and try.

IRA FLATOW: Now, you asked for what can we do with the eggs. Remember we were doing– what else can I do with the eggs, you ask? You ask our listeners. They respond. Let’s go to Pittsburgh.

JEFF POTTER: Thank you, listeners.

IRA FLATOW: Dawn in Pittsburgh, hi.

DAWN: Hi, how are you?

IRA FLATOW: Hi there, go ahead.

DAWN: So I’m Chinese. Cured eggs is a very traditional thing. We typically use duck eggs. That’s even better than chicken eggs. The way that you described is actually an accelerated way to cure it, which is great. So what we use that– I’m going to give three examples.

One would be fried rice. So you just sprinkle it when you do fried rice. That’ll add a little bit of a salty, umami flavor. And another thing we use is to– when you steam white fish. So you would use some of that to get the flavor out better.

Another thing that I would use is grilled vegetables. So let’s say you grow zucchini, egg plant, and then– because I guess we don’t typically grill– but I can see grill will translate well on using some of that on top of the grilled vegetables.

JEFF POTTER: So a question for you. You’re talking about cured eggs, you’re referring to century eggs?

DAWN: Oh, no, not that.

JEFF POTTER: OK, because–

DAWN: Not that.

JEFF POTTER: OK, so you’re talking about cured eggs as cured in salt, as opposed to the lye-based process?

DAWN: Cured in salt, yeah.

JEFF POTTER: OK.

DAWN: Exactly, not that. We call it– I know, a thousand-year-old eggs. [INAUDIBLE], not that.

JEFF POTTER: The danger of talking about food is it makes me really hungry. So now I’m going to go home. I actually have some–

IRA FLATOW: I’m going to give you some of this.

JEFF POTTER: I’ve got some rice at home in my fridge that I actually fried up for lunch today. I should have thought. Now, I’ve got the ingredients for this in my fridge, so I love these tips.

IRA FLATOW: Well, I got to give him some food here. I got to feed him, so thanks for calling.

DAWN: OK.

IRA FLATOW: I have gravlax here. And why is gravlax representative? Except that it’s just cold salmon, right?

JEFF POTTER: It’s cold salmon that’s been pressed in– well, it’s got a salt cure on it. So it’s actually similar– I’ll warn you, mine’s a little salty. So I’m glad you’ve got a cup of water there.

So it’s actually very similar in the process of jerky, in the sense that it’s removing moisture. So in the case of beef jerky, when you put it into a dehydrator, you’re mechanically removing it, laying it, sublimating it out. In the case of salt, you’re removing available moisture by adding in salt that absorbs water, preventing it from being accessible to other microbes.

In the case of gravlax– historically, you can imagine being in a fishing village where you caught some fish and you want to go a couple of days inland. It’s not going to last as long as that beef jerky. Well, none of this lasts very long, because I eat it too fast. But in case of the gravlax, it’s not going to last for days and days. It’s something you can make, put in your fridge, use it within a week.

The beef jerky– with proper heat processing on it– can actually last years.

IRA FLATOW: Years? Wow.

JEFF POTTER: Theoretically. The food safety people don’t say years, but there is nothing that should be problematic there.

IRA FLATOW: I’m Ira Flatow. This is Science Friday from PRI– Public Radio International. Talking with author, cook, and great food expert Jeff Potter, author of Cooking for Geeks.

Now my salivary glands–

[LAUGHTER]

–are working over time. That really was salty, but it was delicious.

JEFF POTTER: Yeah. A little bit of dill, I put a little vodka in there. It’s a solvent.

IRA FLATOW: Of course, it’s medicinal. Let’s say you just want to stick with the old fish and salad. I want to stick with a salad. Can you help us make a perfect dressing for that?

JEFF POTTER: Oh, Lordy, I think a perfect dressing depends upon what you like in your salad.

IRA FLATOW: Just a little bit of balsamic vinegar will do it for me.

JEFF POTTER: I mean, I personally– maybe it’s a good food answer, not a very interesting science answer. Personally, I just do a little bit of olive oil, some oregano, and some– dried oregano’s actually really good.

IRA FLATOW: Well, let’s talk about things that people eat that are raw. And why are they– say, for example, why is beef tartar safe to eat, or even sushi? Why is that safe to eat?

JEFF POTTER: So this goes back to, what’s the food product? What are the sources of safety issues around them– whether they be endemic and wherever the food’s from, or introduced in post-harvest– and then how it’s handled.

In the case of something like sushi or beef tartar, the things that we typically use for those dishes are animals that don’t have a particular issue. So there’s a reason why we don’t typically see things like– I don’t know– cod sushi. Not that it can’t be done. But if you look at most species of– well, many species of tuna, for example, don’t generally have parasites. And they don’t have things like E. coli or salmonella.

If you look at something like beef tartar, you can have surface contamination. So if I was going to try to make somebody a really nice steak tartar, I would actually– and I was wanting to be a little more careful than normal– recognizing that there’s always some risk, and these sorts of things. I would actually dip it in very hot water. Not quite boiling. Call it 180, 185 degrees for 10, 20 seconds.

And what that’s going to do is reduce most of the surface contamination that might exist, in terms of E. coli, down to a level that’s unlikely to cause problems. And then the interior of that muscle, in the case of steak, is considered generally sterile. So it’s a, what’s the food product? What’s the technique you’re using? How do you match the right processes up so that it’s safe?

IRA FLATOW: Let’s say that you really have to cook something, because you just don’t like to eat raw stuff or whatever, and you want to keep the kitchen as cool as possible. What’s the best way to cook?

JEFF POTTER: Oh–

IRA FLATOW: You want to cook something.

JEFF POTTER: Yeah.

IRA FLATOW: I mean, is there a pot you should use, or any sort of–

JEFF POTTER: I would actually tackle it by thinking about traditions of different cultures. This is probably more of an anthropological answer. But if you look at cultures that are closer towards the equator where cooking with a lot of heat is not something they’re going to want to do– so actually, things like stir fries, as opposed to roasts.

IRA FLATOW: Or a pressure cooker.

JEFF POTTER: Or pressure cooker!

IRA FLATOW: It stays in–

JEFF POTTER: So if we want to bring in the science, then– the pressure cooker part is actually really fun, because increasing pressure increases the rate of reactions. So if you take something– let’s say you did want to make that roast I mentioned a minute ago in the middle of summer, but you don’t want your oven on for six or eight hours or whatever.

If you do it in a pressure cooker where your temperature can get up to about 240 degrees– and that’s based on increased pressure. So you can have increase boiling point so the rest of the muscle tissue can get hotter in that environment. Things like the breakdown of collagen will occur much, much faster. So what might normally take six hours might take an hour or two, or half an hour– depends on the exact details of the food. So–

IRA FLATOW: Yeah, that’s good. That’s a good solution.

JEFF POTTER: Yeah, it definitely– modern thing.

IRA FLATOW: Yeah, and then if you want to know more great tips from Jeff, he’s got a book out called Cooking for Geeks– Real Science, Great Hacks, Good Food. Jeff Potter, always great to have you–

JEFF POTTER: Thank you.

IRA FLATOW: –here with us. And bringing me my dinner tonight, because I’m sure that’s what it’s going to be. And if you want to tackle dessert, did you know that chocolate is a crystal? Today is actually the international chocolate lover’s day, and chocolate is a crystal. You can test it out in your very own kitchen, courtesy of the Science Friday Educate team. Head over to sciencefriday.com/chocolate to try it. Bon appetit– to me, every day is chocolate day.

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