IRA FLATOW: This is Science Friday. I’m Ira Flatow. We’re here talking about food and holiday stuff, all kinds of questions about cooking food. You have any questions about that, we’d like to hear from you. Our number– 844-724-8255. Sitting in with me is Sophie Bushwick, Technology Editor at Scientific American. Do you do a lot of cooking during the holiday season, Sophie?

SOPHIE BUSHWICK: I honestly– I do a lot of– I’ll be the sous chef a lot for my parents who host Thanksgiving. And so I’ll help out, but I usually am not the one doing the cooking.

IRA FLATOW: OK. We’re going to– well, hopefully, a lot of folks will be asking questions. We usually get lots of questions here. And I want to bring on Dan Souza, chef of America’s Test Kitchen based in Boston, Massachusetts. He’s sticking around with us. He’s also Editor-in-Chief of Cook’s Illustrated. And, as I say, we’re answering your questions about the science behind cooking, our favorite holiday foods.

Our number– 844-724-8255. 844-SCITALK. You can also tweet us @scifri. And let’s go right to the phones because here’s, I think, the most popular question we get. Sharon in Fair Lawn, New Jersey. Welcome to Science Friday.

SHARON: Hi. I have problems getting all of the turkey to come out right. Most of it comes out beautiful. Some of it comes out wrong. And I have spent a fortune on fancy meat thermometers. And I know not to put the thing against a bone, and I know not to leave it too close to the surface, and I still get some coming out raw and some coming out just fine.

IRA FLATOW: You are in–

SHARON: What am I doing wrong?

IRA FLATOW: –good company. I can’t tell you how many times I have asked this question, and our listeners. And maybe, Dan, tell us what we’re doing wrong here.

DAN SOUZA: Yeah. So I want to take the blame off of the caller and off of you, Ira, because this is– it’s actually really an issue of the turkey shape and size where– and the muscle composition, where you have the breast meat which is much leaner and needs to cook to about 160 to 165 degrees.

And then you have the dark meat, which is denser and kind of tucked away under the bird, and that needs to get to a higher temperature about 175 degrees in order to be nice. So it’s this really tricky battle of trying to get these things to line up.

But there are some strategies you can use. One that I think is really the simplest– a little bit of upfront prep, but then you get a beautiful bird at the end– is to spatchcock the bird. Or butterfly it is another term. And so you’re using some really strong kitchen shears. You’re cutting out the back bone, flipping the turkey over so that all the skin is facing up, and you’re pressing down on the breast bone to flatten it out a little bit.

And what’s great about this method– you put it directly onto a sheet pan or a roasting pan. And the heat from the bottom of the metal goes right into the dark meat. So those thighs are kind of splayed out there. And so they cook a lot more quickly than they normally would. And that should help things cook at the same pace.

If you’re running into issues where you’re temping the breast and it’s getting too hot by the time– waiting for the dark meat to come up, it’s really helpful to make a kind of a– almost a heart shaped little shield out of aluminum foil that you can pop over the top of the breast, and that reflects off some of the radiant heat coming from the oven. And that will actually slow down the cooking of that delicate breast meat while you wait for the dark meat to come up. So using a combination of those two things, you can really dial it in and kind of control those variables.

SOPHIE BUSHWICK: My question about spatchcocking is that I know about spatchcocking chickens, but turkeys can be really big. So is it– do you ever run into an issue with spatchcocking like a really big bird and not being able to fit it on the pan?

DAN SOUZA: Yeah. So– yes, if you’re working with a really large bird that can definitely be tricky. We really love to look for birds that are in the 12 to 14 pounds range, so it’s on the smaller side. And if you want to do like– if you’re serving a lot more people doing a separate roasting pan that has some thighs in it or another chicken breast.

The reason being these problems we’re talking about, they get exacerbated as you go up in size on the bird because you have so much more volume to get through in terms of cooking that breast. But a spatchcocked 12 to 14 pound bird will absolutely fit nicely in a roasting pan or on a sheet pan.

IRA FLATOW: Good question. Yeah, good answer, too. Let’s go to Baltimore County, Maryland to Woodstock there. Hi. Welcome to Science Friday.

WOODSTOCK: Yeah. Good afternoon. Yeah, my question is for Dave Souza about how to avoid the airplane hangar effect in a two-crust from scratch apple pie.

IRA FLATOW: Wow. What– tell it– [LAUGHS] what is that, Woodstock? What is that effect describe it to us for people who have– looking at the radio now.

WOODSTOCK: You got the top crust of your apple pie. It’s finished baking. It is a big dome. It’s domed up. It looks like a Norman Rockwell painting. And then you let the pie cool. You cut into it, and it’s just a big pocket of air. And there’s a sad thing of apple filling lying down in the bottom crust.

IRA FLATOW: Wow.

SOPHIE BUSHWICK: That sounds tragic.

WOODSTOCK: Yeah I think I heard Julie with Chris Kimball years ago refer to it as an airplane hangar effect. And I presumed that that was the official term in the bakery trade.

IRA FLATOW: Well, Dan, it sounds like we have a heat physics question here.

DAN SOUZA: Yeah. This is a great question. And I actually have never heard it referred to as the airplane hangar, but I knew immediately what you were talking about. It’s a really good visual– that huge kind of gap between the filling and the crust of the top.

So the reason this happens is the apples are collapsing during baking, but that crust sets in shape much earlier in the process. And so there’s actually a really nifty technique that we’ve employed in some of our recipes where we take advantage of a food science phenomenon called persistent firmness, where if calcium and pectin-rich– some pieces of produce that are calcium and pectin-rich, if you heat them to a low temperatures, usually in the kind of 130 to 150 range, and you let them hang there for about 20 to 30 minutes, you kind of reinforce some of that pectin and those bonds. And so that even after you heat it to a higher temperature later, they’ll maintain more of their structure, and they won’t collapse as much.

So an easy way to do it is to get a little butter going in a skillet and throw your apples in there and sugar. Toss, toss, toss, until everything’s kind of nice and warm– not super hot, but warm. Cover it, and let it sit for about 20 minutes off heat, and then use that in your pie. And it works remarkably well. You’ll find that you will have much less of an airplane hangar effect and a much fuller slice of pie.

IRA FLATOW: You’re civil engineering your pie.

[LAUGHTER]

DAN SOUZA: Pie is a big engineering feat, so that makes sense.

IRA FLATOW: Let’s go to Wayne in Queens, New York. Hi, Wayne. Wayne? Yes, go ahead.

WAYNE: Oh, hello. How are you doing Thank you for taking my call. Quick question. I have– like I say, I have some vegan family members. And Thanksgiving day has a lot of meat and a lot of heavy meals, and I need to shed a few pounds myself.

I want to know do you guys have a recipe for keeping in the family of gourds, like we were talking earlier, for a butternut squash with not so much heavy cream and stuff like that– something that’s relatively light that I could make easily?

IRA FLATOW: Good question.

WAYNE: [INAUDIBLE]

IRA FLATOW: OK. Thank you for calling. Yeah. What do you do for vegetarians, and maybe something with butternut squash? Dan, got something there?

DAN SOUZA: Absolutely. Yeah. And I– honestly, I think there’s so many great sides for vegetarians you almost don’t even need a main. I think turkey gets a lot of the credit, but we all come to the table for those sides.

But a really nice way to treat butternut squash is a recipe I did a long time ago, where you peel it and then slice it thin. So you have kind of 1/4 inch thick slices of it. Lay them out on a sheet pan with a bunch of olive oil. If you don’t want to use butter, that’s fine, and roast them low in the oven so they get nice browning, especially on the bottom. And take them out. They get nice and tender. And then spread them out on a platter, and they’re basically a canvas for flavors.

So I love doing hazelnuts on top and chives and lemon. But you could do like a really nice tahini and lemon situation. It’s kind of up to you at that point how you want to top them. But it really makes the squash front and center and that nice browning. And you’re not adding more sweetness to it because it’s already sweet enough. So you’re going with nice savory combinations on top. And it’s a gorgeous platter to put out for the table.

IRA FLATOW: Yeah. You don’t have to do that on Thanksgiving. You can use that– I’m getting hungry listening.

SOPHIE BUSHWICK: I also really like that because a lot of times something that’s already sweet– like the sweet potatoes and marshmallows on top. Why did we start putting marshmallows on top?

DAN SOUZA: It’s true. I know. I know. I mean, it takes it fully in dessert territory, not that I won’t totally go for that dish.

IRA FLATOW: Old family recipes. That’s what happened.

SOPHIE BUSHWICK: [LAUGHS]

DAN SOUZA: Yeah.

SOPHIE BUSHWICK: Yes.

IRA FLATOW: All right. Let’s go to Rochester, New York. Julie, hi. Welcome to Science Friday.

JULIE: Hi.

IRA FLATOW: Go ahead.

JULIE: So I’m now a vegetarian. But many years ago, over 20 years ago, I cooked my first and only turkey, and I didn’t know what I was doing so I got a very large turkey. And I didn’t defrost it for long enough. So what I ended up doing was– I know this is really bad. But in an attempt to get all the stuff inside out and make sure it was ready for the oven, I ended up running it under water and kind of aggressively defrosting it. So my question is, how close did I come to food poisoning all of my guests?

[LAUGHTER]

DAN SOUZA: Oh, wow. That’s some– this is some deep forensic research we have to do here to figure that out. You definitely obviously want to be careful with poultry and thawing and all that. And the best way, if you can, is to just put it in your fridge long enough ahead of time that it’s going to be totally thawed out. So you don’t have be running underwater and stuff like that.

But there’s a couple things with food safety. So there’s obviously how you handle it beforehand. And you don’t want to keep it at a warm temperature for more than two hours. You want to keep it refrigerated.

But the final step in all of this process is the cooking. And so if you have messed up a little bit along the way, as long as you cook that bird to a high enough internal temperature– and what we really shoot for is 165 will get it done in less than a second. And that’s why the USDA kind of recommends that.

You can go a little bit lower than that as long as it stays at that temperature long enough. So 160 degrees if you’re there for– I think it’s something like a minute and a half. But go for like five minutes or more. It’ll kill the same number of bacteria in terms of salmonella. So that final step is the most crucial.

So yes, you want to thought in your fridge if you can. And if you’re doing it last minute under running water, you can put it in cold water, and every 30 minutes you want to change that out for fresh cold water, just to make sure that the temperature isn’t climbing up too much. That’s kind of best practices. But yeah, that final step using a good instant read thermometer and looking for the right safe temp is key.

IRA FLATOW: I hate it when I poison my guests.

SOPHIE BUSHWICK: Well, when I heard this story–

DAN SOUZA: Yeah. No one wants that.

SOPHIE BUSHWICK: –I heard– I thought this was going to be worse. I thought it was going to be a case of a partially frozen turkey being deep fried and exploding.

IRA FLATOW: [LAUGHS] [INAUDIBLE]

SOPHIE BUSHWICK: I mean, are you pro or anti deep frying turkey in general?

DAN SOUZA: Oh, me? Deep frying is a fabulous method to cook a turkey, as long as you can do it safely. So you have the fryer set up far away from the house. You’re working with a very dry bird. Obviously, you don’t want ice and water involved there. And you have the right rig and set-up for it. Your pot’s not overfilled with oil.

But it’s incredibly efficient way. It can cook a turkey and probably half the time it takes to roast it. You do get great skin. And frying is really a steaming method. So the outside is getting exposed to the hot oil and crisping, but the inside is steaming at a relatively gentle temperature. So you get fabulous meat out of that as well.

IRA FLATOW: I think that’s what we’re doing.

DAN SOUZA: Be careful.

IRA FLATOW: Yeah. We’re doing that this year. We’ve done it a few times. This is Science Friday from WNYC Studios talking about people making their Thanksgiving food and lots of questions. Let’s go to Maine. Rob, in Maine, welcome to Science Friday.

ROB: Hey. Good afternoon. Thank you. I’m located in Caribou, Maine, northern Aroostook County. We’re big-time potato production up here. This time of year, friends and neighbors and family and everybody’s got 50-pound sacks of potatoes all over the place of all different kinds of varieties. And I was wondering if you’d be willing to discuss different varieties and their best intended uses. We have bakers and fryers and mashers and sweet potatoes, and yeah, that’d be interesting to hear.

IRA FLATOW: OK. Thanks for calling, Rob.

DAN SOUZA: Absolutely. I have family from up in Maine– not quite that far up. But I love Maine potatoes, so I really appreciate this call.

So there are really three categories that you’re going to see in most supermarkets, and we can break them down basically on their starch content. And so you have– at the high end of the starch range, you have russet potatoes. In the middle, you have Yukon gold or kind of an all-purpose potato. And then you have your red potatoes, which can be different colors, but they’re the small, creamy ones.

And so you’re looking at about 20% starch by weight up in the russets, and then 18 and 16 as you go down there. And that really determines the final texture that they cook up to. So you have russets that will fracture a lot as they cook, and you get that dry, fluffy texture.

So they’re fabulous for mashed potatoes because they can soak up so much richness. They’re also really ideal for roasting and getting that crisp texture and for French fries because they have kind of a lower moisture content proportionally.

On the other– on the far end of the spectrum with the red potatoes, they really hold their shape well because they don’t have as much starch. They don’t break up into that fluffy texture. They remain really creamy. So potato salads, they are fabulous with. And they’re really good in soups because they hold together. So that’s those.

And then the all-purpose potato– the Yukon gold is the most common one– it really sits in the middle. And so you can make a great mash with it. You can roast it. It will hold its shape relatively well in a salad. But if you’re unsure, Yukon gold is a pretty safe place to go. But if you’re baking a potato, you want to go for your russets. Or you’re definitely going to do a salad, the reds are nice.

IRA FLATOW: Well, in your experience with all these Thanksgiving food, what is the easiest thing to make for somebody who’s starting out making a Thanksgiving meal?

DAN SOUZA: The easiest thing– I mean, I think good mashed potatoes are pretty easy. I would probably go for that. And you want to start–

IRA FLATOW: And what makes good mashed potatoes?

DAN SOUZA: So I think– you’re starting with your potatoes cut to about the same size. That’s really key. So you can make them smaller slices. They just need to be the same dimension so that you don’t get some parts over cooking while the other part’s not cooked through.

You want to start them in cold, well-salted water. Bring it up, and then don’t boil it. Just kind of a– just a simmer there so you don’t break them apart. Strain them off. And you want to process them while they’re still hot. So going through a ricer or a food mill will give you a really smooth texture.

And then add your butter first, which will help coat some of that starch before you add your milk or your cream to it. And that helps it stay really nice and fluffy as opposed to getting gummy or too dense. And then use plenty of salt. Season it up with salt.

And make them no more than an hour before dinner. And if you do make them ahead of time, put them in a pot– I mean put them in a bowl over a pot of simmering water so that they stay nice and hot. That’s kind of the key there. But I think that’s a pretty easy one to start with.

IRA FLATOW: Yeah. And there’s something about food that tastes better the second day– some of the turkeys and whatever.

DAN SOUZA: [LAUGHS] Well, that’s true. And you have to make everything so that you can make that Thanksgiving sandwich in the evening, right? I mean, that is– the meal is good, but the sandwich is great.

SOPHIE BUSHWICK: Yeah. I agree. I think that the leftovers are– they taste better as leftovers than they do the day of Thanksgiving. And I don’t know why, but they do.

IRA FLATOW: Yeah. Well, all those sauces and whatever take time. They sit there–

SOPHIE BUSHWICK: Yeah. The flavors have to meld together I guess.

IRA FLATOW: They sink in. Well, Sophie–

DAN SOUZA: They definitely do. Yeah.

IRA FLATOW: Yeah. Is that well known? I mean, it’s not just our imagination, Dan?

DAN SOUZA: No, not at all. Not at all. Especially in something like a stew, where you have big pieces of meat kind of in there, and you get flavor penetration from the sauce going into it and kind of vice versa. So no, it’s fact. A stew will taste better the next day. And there’s some recipes and stews that will go a few days and taste their best. So yeah, there’s truth to that.

IRA FLATOW: That’s great. Dan, I want to thank you for taking time to be with us today and for all your advice.

DAN SOUZA: Oh, it was a pleasure to be here. Thanks for having me.

IRA FLATOW: Dan Souza– Editor-in-Chief of Cook’s Illustrated. Also, Sophie, thank you for hanging out with us today.

SOPHIE BUSHWICK: It’s been a pleasure.

IRA FLATOW: Sophie Bushwick, Technology Editor at Scientific American.

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