Why do apples turn brown when you cut them?
This episode is sponsored by Catherine Nicole Photography. Catherine Nicole photography beautifully captures your life's most important moments. Weddings, engagements, graduations, celebrations, your pets, and anything else that's important to you. Cherish the moments that passed too quickly with Catherine Nicole Photography.
Melissa:I'm so excited to be partnering with Catherine Nicole Photography. Jam and I have both personally worked with her. I've done a Solo photo shoot, and Jam did one with your wife and your dogs. And
Jam:Mhmm. Mhmm.
Melissa:I think Nicole, the owner, does a great job of capturing The actual beauty of someone's personality and getting them to laugh. I had so much fun with her on our photo shoot, and I Love her Instagram. I'm just so excited to
Melissa:be working with Catherine Nicole photography.
Jam:So check her out on Instagram, at the very least to see What amazing stuff she does, and to thank her for sponsoring our show. At catherine nicole photography. That's Catherine with a c. Or check out her website, catherine nicole photography.com.
Melissa:And now on to the show. Hey. I'm Melissa.
Jam:I'm Jam.
Melissa:And I'm a chemist.
Jam:And I'm not.
Melissa:And welcome to chemistry for your life.
Jam:The podcast helps you understand the chemistry of your everyday life.
Melissa:Okay, Jam. I'm so excited about today's episode.
Jam:Okay. I'm ready to be excited about it too once I find out what it is.
Melissa:Okay. We're gonna talk about why apples turn brown. Oh. You know, you cut them, and then they get that brown layer?
Jam:The inside part. You're not talking about, like, rotten apples. You're talking about, like, The part yeah. Yeah. When you take some bites or whatever Right.
Jam:And it turns brown.
Melissa:And the weirdest thing happened, though. I was so excited about this that I told a few people. Uh-huh. Everyone asked. But what about is it all fruit?
Melissa:Does all fruit turn brown for the same reason? I was like, okay. I guess I'll answer with that too. So my answer is yes. Most fruit turns brown for the same reason.
Melissa:So I'm just answering it straight out the gate.
Jam:Okay. Okay. But apples are better than most fruit, and so It's kinda like, you know
Melissa:For some reason, I only thought about apples in the beginning until all the people asked me that question. So
Jam:Maybe it's more notorious with apples. I mean, like
Melissa:Maybe so.
Jam:They are Pretty light colored inside, and then brown. I mean, I remember first seeing an apple turn brownish As a kid and being, like, uh-oh, mom. I think this apple's not good anymore. She's, like, no. It's fine.
Jam:You can eat it. It's, like, it looks pretty
Melissa:Gnarly.
Jam:Yeah. And contrasting to what it's supposed to look like.
Melissa:Mhmm. Well, we're gonna talk about why it turns brown, but we're also gonna talk about why that apple Why that lemon juice trick works?
Jam:Okay.
Melissa:And we're gonna talk about this fun extra thing I discovered. I'm so excited about What?
Jam:Is there a contingency on this fund? Do I have to get something achieve something?
Melissa:No. I'm so excited. I'm gonna tell you no matter what. Oh, good. Alright.
Melissa:Good. Okay. Are you ready?
Jam:I'm ready. I'm in.
Melissa:So why do you think what have you heard about why apples turn brown?
Jam:Oxygen.
Melissa:That's exactly right. That's what everyone says. Everyone says. Isn't it just oxidation of some kind? Isn't it just oxygen reacting with it?
Melissa:But my question for you is do you guys really know, you, Jam, and all the people who said that to me And all the listeners listening, do you really know what it means that it's exposed to air and it turns brown?
Jam:Enrazzo's gonna be lumped in with the masses
Melissa:like a
Jam:like a swine. I'm one of the elite too. Okay? Even though I don't know stuff, I'm in on this with you, and I find this stuff out. And now that people don't know about it, I find it out a little earlier.
Jam:Let me think. I just I didn't say that knowing that I could like, thinking that it wouldn't even be right. I just that's all I could think of.
Melissa:Well, that's that's the first part. So do you want a second to think about if you can describe it?
Jam:Yes. I do. What I can think of is that It's a part of the apple that was until you cut it or bit it, was protected by It's skin and stuff, so you've exposed it. And that would explain why Apple's last a long time before you've, like, cut them open or something. So is it just that oxygen and maybe even other things in the air, I don't know, start to, like I don't even know what to say is happening.
Jam:Like, It's getting at this part that was protected. It is like Mhmm. Starting to make something happen that the apple is able to prevent before. Trees it's in trees' best interest to keep their fruit in good condition as long as possible. Yeah.
Jam:But is it like is it similar to what happens with rotting or no?
Melissa:Well, I'm just gonna stop and say Your idea is actually a really good one. That it's a protected part that's no longer protected, and now something happens. That's key. Okay. So I but I'm also gonna say, I wanted you to have the opportunity to do that because I think a lot of people Are like, I know what happens.
Melissa:It gets exposed to the air, and then it turns brown. And sort of like with rainbows, I think A lot of people know that without knowing all of the why behind it.
Jam:Right. The why is a is the only part that's interesting.
Melissa:Mhmm.
Jam:It's not interesting to just know that things happen.
Melissa:But it sort of feels like you know because you know it has to do with the air.
Jam:Right. And everybody feels like I'm qualified to know thing nothing about apples. I eat apples too. Exactly. It's like I
Melissa:don't know if people feel that way, but I just always think it's good for us to stop and think, like, how much do I really know about this? Right. Right. Why I wanted to do that. Because my answer to it was about the same.
Melissa:I was like, it gets oxidized, Which I know what oxidizing is, and so I got the first half of it somewhat right. But I didn't know any of what I'm about to tell you, and that is always very exciting me?
Jam:Is it breaking it down? It's kind of, I guess, the better way I should've said it. Not like rotting, but, like, breaking something down.
Melissa:Not really. Okay. So we'll talk but we can talk about it.
Jam:Okay. Alright.
Melissa:Okay. So when you cut into fruit Uh-huh. And expose it to air, the part that has been protected, like you said, Is no longer protected. Yeah. So the damaged cells release an enzyme.
Melissa:Does this sound familiar?
Jam:It does sound familiar.
Melissa:Enzyme is activated in oxygen Mhmm. To oxidize certain Types of alcohols that are in the sugar Mhmm. To, what's called a quinone. Basically, they just add bonds to oxygen. And That forms a protective layer Mhmm.
Melissa:That keeps that part of the fruit safe. Nice. So now imagine the apple on a tree, and it gets nicked and that part is exposed Uh-huh. And no brown over, but it still grows. Uh-huh.
Melissa:It's protecting that layer of the apple against bacteria.
Jam:Nice.
Melissa:So just like with onions, Yeah. It's protecting itself. That's crazy. Excited.
Jam:It's so crazy.
Melissa:It is so crazy.
Jam:It's I mean, like, I think whenever we did the onions episode, which if you have not listened to, please go back and listen to it.
Melissa:It's one of my top five favorites of all time.
Jam:So fun to learn about that. That one's like a protective in a way that feels almost like like, it's a lot more defensive.
Melissa:Offensive.
Jam:Yes. Yeah. I mean, like, But it is based on the fact that something happened to it first. Mhmm. So it's it is a defense.
Jam:It's like pepper spray. You know what I mean? Yeah. It's like that's you didn't start it.
Melissa:Right.
Jam:With the pepper spray, you're responding to being harmed or whatever.
Melissa:Mhmm.
Jam:But it's so much more about causing something to the person or thing
Melissa:Mhmm.
Jam:Whatever. Whereas, in this case, it's just trying to protect its fruit further.
Melissa:Mhmm.
Jam:Like, The brown part doesn't harm us. Right. It's like, ah, like, my lips are burning or something, which would be horrible. It's like you gotta eat those apples fast. But that's crazy because it is just trying to keep it alive longer or keep it growing longer or whatever.
Melissa:Right.
Jam:That's nuts.
Melissa:Well, it gets crazier.
Jam:Oh, really?
Melissa:Mhmm. So that happens. And you're like, that's amazing. That is so amazing. That's the initial reaction.
Melissa:Again, almost the same type of thing. When it's damaged, it does that. Uh-huh. But the thing it forms called quinones, I have worked with quinones Very little, but I have, and they're not brown. Uh-huh.
Melissa:So I was like, okay. What's going on here? Everyone says it's This enzyme called polyphenol oxidase, and it turns these polyphenols from polyphenols into quinones. But none of that's brown. I'm like Yeah.
Melissa:I've got some questions. Yeah. So I went and looked into it further. Mhmm. And, actually, those quinones, it's the type of compound it turns into after oxidizing Uh-huh.
Melissa:Can react with one another to form polymers So that are brown.
Jam:Just like my art reaction.
Melissa:Just like my art
Jam:reaction. All delicious and brown Mhmm. In that case too.
Melissa:Yeah. So the flavor doesn't change a ton from these, and it is more of just that protective layer Mhmm. Is against bacteria is then reacting further.
Jam:But It is a little slimier though. Mhmm. You know?
Melissa:It's got that little polymer on there. It does superficially change. Like, the texture, Sure. The color of that changes, but it doesn't Yeah. It doesn't change the
Jam:The taste.
Melissa:Level of health. Like, it's not unsafe.
Jam:Right.
Melissa:Right. Mhmm.
Jam:It's actually better for you. So it's better to, like, skin an apple, leave it out on the counter for an hour, and then eat it.
Melissa:I don't think there's any scientific evidence behind that. You can look up the scientific It's called raw apples. You
Jam:should only be eating raw apples.
Melissa:Oh my gosh. Okay. So that's it. That's why your apple turns brown.
Jam:Dude, that's crazy.
Melissa:It is so crazy. It's so cool. I was so excited. I thought, I can't believe there are more things like onions. I just get so excited when I learn crazy cool new stuff like that.
Melissa:And I've always noticed my apple turning brown, and I've always been frustrated, but it's actually protecting you. Mhmm. Mhmm. Mhmm. And it does not change The level of safety, you can still eat it.
Melissa:It's still good. It's just protecting itself. It's just trying to make sure that no bacteria can get in and mess up that fruit.
Jam:It's fascinating how much of nature is just trying to protect itself. Mhmm. Like, whether it's plant or a insect or animal or whatever.
Melissa:Mhmm.
Jam:It's just so cool. There's so much there. It's like, man, I just would never have thought that so many things would be answered by that question.
Melissa:I know.
Jam:Onions, apples. Man.
Melissa:Onions, apples. Lots of enzymes taking care of business.
Jam:One time one of the most memorable times I have of an apple being brown was I ate part of an apple And put it on my dad's desk, and then literally a day later, I was, like, 5 probably. My grandmother was at her house, and she was, like, whose apple is this? And I was a little bit scared to, like I mean, just of not not being in trouble because I didn't finish it. Mhmm. I I was like, oh, that's mine, but it's brown now.
Jam:She said, oh, it's okay. You can you can still eat it. It's it's fine. Tastes the same. And I didn't wanna say I left it there yesterday.
Jam:And so I was like, oh, yeah. Okay. And just took it. And I was like, uh-huh. Oh, yeah.
Jam:So good. And just, like, Took a bite out of it expecting it to not taste great, but also wanted to act like
Melissa:You weren't gonna get in trouble.
Jam:Yeah. And, like, I didn't leave it there yesterday.
Melissa:Mhmm. How did it taste?
Jam:I don't know. It's probably fine. I probably, like, as soon as you turned around and went through it away, it's close. Superstitious.
Melissa:I did wanna say
Jam:Okay.
Melissa:The polymer is Called melanin. Mhmm. The polymer that's formed when they react with each other. And we didn't explain a lot about the definition of enzymes. We have talked about that before.
Jam:Oh, yeah. Yeah. Yeah.
Melissa:But, basically, all an enzyme does is help a reaction happen. So it's likely that these polyphenols would have oxidized just in air, but very, very slowly. Mhmm. And because that enzyme is formed, it helps make that reaction go much faster. Okay.
Melissa:So we've talked about that in the past. I think we did talk about it in-depth on the onion episode. Mhmm. So you can go back and check some of those out.
Jam:Yeah. I I'm feeling I might get some of those words mixed up when I try to explain this. Okay. So you have an apple.
Melissa:Mhmm.
Jam:Or other kinds of fruit, but apple
Melissa:is
Jam:the one we all think of first. You take a bite or you cut it open or whatever, and it's sitting there. You've just damaged a lot of cells in this thing.
Melissa:Mhmm.
Jam:So the Apple Built in response to that kind of situation is to release and They release an enzyme or they release the polyphenol?
Melissa:The polyphenols are or phenol. It doesn't matter. Are in the through already.
Jam:Okay. Okay. So it releases an enzyme Mhmm. And it reacts with or Some things with the polyphenol Mhmm. And oxidizes Mhmm.
Jam:Which forms A polymer
Melissa:Yes.
Jam:That's that's the brown part. But the part, even that happens already before then, is to protect whatever part is damaged or exposed or whatever.
Melissa:Yes.
Jam:And the is the polymer protective, or is it a, like, kinda just Byproduct effect.
Melissa:So I believe the quinones that are formed so initially, the polyphenols Uh-huh. Interact with oxygen. This has to be in the presence of oxygen
Jam:Okay.
Melissa:And the enzyme to become oxidized
Jam:Okay.
Melissa:Into a different type of compound called quinone.
Jam:Call it quinone. Okay. Once that all happens, the oxidation's happened, then it's a quinone.
Melissa:And then the quinone polymer polymerizes.
Jam:Okay.
Melissa:So I think the quinone has some Toxic properties to certain types of bacteria. I don't know for a fact. I saw that in one source. Couldn't confirm it anywhere else, But it seems like something in the oxidized state Mhmm. Is going to be protective.
Jam:Remind me what the quinone, like, reacts with or whatever's with to from the polymer?
Melissa:Itself.
Jam:Itself.
Melissa:It reacts with other quinones.
Jam:Okay.
Melissa:And just I don't know if anyone cares about this. Mhmm. But all a polyphenol is, it sounds like a big word, it's a ring of 6 carbons That are nice in holding hands, or it's called an aromatic ring. Mhmm. And they're in this Nice six membered ring, and it's very stable, and it has multiple alcohol groups.
Melissa:So That's why it's called the polyphenol.
Jam:Okay.
Melissa:And then these alcohol groups, which are an o h group, are changed To just have 2 bonds to the oxygen, and they get rid of the hydrogen. And that's why it's called oxidation. There's extra bonds to the oxygen. And we also talked about that extra bonds to oxygen in the bleach episode.
Jam:Mhmm. Got it.
Melissa:So don't worry too much about the structures or anything like That that's just all the enzyme is doing is helping there be more bonds to oxygen, and that's why it's called oxidizing.
Jam:Okay. So the quinones react with themselves, other quinones.
Melissa:Mhmm.
Jam:And that forms a polymer, which is what we see as the apple turning brown.
Melissa:Yep. Some nice brown melanin polymer.
Jam:Interesting.
Melissa:Isn't that amazing?
Jam:Yeah. That really is.
Melissa:I am a I'm blown away. I was so amazed. And While I was reading it, I kept finding all reading about this, studying of this, I found all these papers studying these enzymes and how quickly they happen and What gets oxidized? All this stuff in these chemistry journals. There are people who are studying what gets oxidized on the surface of bananas, and that is dopamine.
Melissa:Things they found. And so it's all this really cool stuff. They studied the optimal pH. Uh-huh. And the pH is a level of acidity.
Melissa:The optimal pH is closer to neutral for this reaction to happen. So that's why when you squeeze lemon juice on an apple, The reaction can't happen because it's very acidic, which means the pH is very low.
Jam:It's weird. What what situations do people Squeeze lemon juice on apples.
Melissa:You never heard that? You squeeze lemon juice on an apple to keep it from getting brown if you're not gonna eat it right away. Oh. You cut up your apple.
Jam:Like a
Melissa:You're not ready for it? Squeeze some lemon juice on it. Interesting. Same thing for avocados. Squeeze some lemon juice on them.
Melissa:And Those slices of apples that they sell in the store that are chopped up but don't have anything on it? Mhmm.
Jam:A lot
Melissa:of times, they'll soak them in vitamin c, Which is ascorbic acid. So it has a low enough pH to wear.
Jam:Woah.
Melissa:That doesn't happen, and it It's in the acidic environment that keeps the enzyme from working.
Jam:That's nuts.
Melissa:Isn't that amazing?
Jam:Yeah. That really is.
Melissa:I was having so much fun learning about this. It was So incredible to me. And then I found Uh-huh. The craziest thing of all.
Jam:Yes.
Melissa:Are you ready?
Jam:Yes.
Melissa:Not only.
Jam:Please tell me as fast as possible, I can't wait any longer. I have to know so badly. I can't wait any longer. Please don't make me wait any longer.
Melissa:No. Please just tell me. Not only has someone modified an apple Uh-huh. To not turn brown, But it has been approved by the USDA, and it is on shelves now. You can buy apples that don't turn brown.
Melissa:How? They modified the RNA, I believe, which is, beyond my scope Completely.
Jam:But wait a second. What are we losing? What are we losing by not having the apple be able to turn brown?
Melissa:All they've done is Press the expression of that enzyme. The gene that expresses that enzyme is my understanding, but they are made by a Place called Okanagan Specialty Foods. Mhmm. And they go by the name Arctic Granny and Arctic Golden. So if you find an arctic granny or an arctic golden apple, cut it up and see how it doesn't ever change to brown.
Jam:Well, Would that, like is that protective element gone then too? Like, the apple gets nicked in transit?
Melissa:Possibly.
Jam:Dang. That's what I
Melissa:was thinking. Like, what are we missing? I haven't had 1 nor have I experienced it.
Jam:Listeners, keep your eyes peeled, and we will too, to find one of the apples somewhere.
Melissa:That would be amazing.
Jam:Yeah.
Melissa:Now that I know to look for it, Right now, I only eat pink lady apples.
Jam:Love pink lady.
Melissa:And I only cut into them. I do not Bite into apples. I only chop them into slices. I don't like the way it makes my teeth feel the bite into it.
Jam:Interesting.
Melissa:Sometimes they do turn brown, And it makes me sad.
Jam:Uh-huh.
Melissa:They don't turn brown as quickly. I think they're tart. I think they might be a little bit more acidic Uh-huh. As those red apples do. They turn brown super fast.
Jam:Right?
Melissa:But I would be interested to check out an Apple that doesn't.
Jam:Yeah. Me too. I'm also really glad that apples don't respond like onions do. Because seriously, the only thing that keeps me from just snacking on the raw onion is the fact that I'll be crying. So, like, I'm so glad that Apples of death too.
Melissa:Yeah. So that's it? Sweet. Isn't that amazing? They have genetically modified Yeah.
Melissa:These apples to not turn brown, and they're on shelves, and you can buy them. And there are people studying all of this about why Apples turn brown, and bananas turn brown, and avocados. And it just is amazing to me that people are working on things like that.
Jam:Yeah. That really is amazing. And, like, Maybe there is more of a benefit to it than we could think of, but also wouldn't just the knowledge and ability to kind of adjust sense of that be Enough benefit for some potential unknown future Mhmm. Thing.
Melissa:Yeah.
Jam:So it's like, maybe it's just a nice to have for now as far as we know.
Melissa:Right.
Jam:But maybe has a future huge importance.
Melissa:Yeah. I think it's really cool.
Jam:Yeah. And I can't do it, so I'm glad that somebody else figured out how to.
Melissa:Yeah. I really I'm consistently blown away by the things I learn when we tackle topics for this show. So I was amazed. I thought it was Fun. Couldn't wait to share it.
Melissa:So excited about how apples are protecting themselves and how people are learning how to change that. Both of those things blew my mind. It really was I was like, This is the ending episode all over again. I'm so happy. I have so much stuff to share.
Melissa:This is all amazing to me. So
Jam:Well, that was cool. Thank you for telling us.
Melissa:Oh, you are so welcome. Thanks for coming. Thanks to all of you listeners also for coming and hearing about Apples today. So any good updates from your life that you wanna share this week?
Jam:Okay. So something big that happened this week was something that is scary, honestly. I changed email apps.
Melissa:You're gonna share about email?
Jam:I Is
Melissa:that too mean? No. Okay. Part of
Jam:it out of necessity, one of the email address I'm having to use to work with Specific client is not a Gmail one. So they might have to do something to use an app that would allow me to use to have a non Gmail and Gmail stuff all in one place. Mhmm. And we've got, you know, an address for the podcasts like that. So it's like, I need to have one place for everything.
Melissa:Right.
Jam:That's been fine for Gmail because I can do it all there. But suddenly, a non Gmail appears.
Melissa:Oh.
Jam:And I've gotta figure out how to have just as simple of a workflow to see all my emails. Super easy. So I started using this email app called Spark, and it is very good. And I like it very much. The pain of having to switch and knowing I needed to to something that would let me see everything
Melissa:Mhmm.
Jam:Was very quickly alleviated by this cool app Nice. Called spark. And so if you need anyone out there needs a different email thing, you're in the situation I'm in, you've got different apps in your phone for email, do not do that. Use something like Spark, and it's cool because it has some features that I had to do certain things to get added to my Gmail?
Melissa:Mhmm.
Jam:At one
Melissa:point,
Jam:I had to install this whole thing to schedule emails so they would send at certain times that I wanted them to. So I could write a few emails, Have them send the next morning so people aren't wondering why I'm emailing it midnight.
Melissa:Yeah. I wish I could do that with text messages.
Jam:Yes. Yeah. But, Anyways, that was a big change that I've been excited about. Was not excited to have to do, but since then, I've been like, this is so nice.
Melissa:Jam Robinson, Emily's technological husband at it again.
Jam:Yep. Talking about email. So that was my that was my very exciting week. What happened in your week?
Melissa:So I got home, and I had a letter in the mail. Uh-huh. And I love letters, and I opened it. It was obviously for my sister, Abigailene. And I opened it, and she sent me a coloring page with Nani Doss, the giggling granny Who poisoned her husbands?
Jam:Mhmm.
Melissa:And she wrote me a note that said that she got a book of serial killers coloring book of serial killers for Christmas, and she colored me 1 and included a blank page of a different serial killer for me to color, and then I get to send that back. And then she'll color another one and send it back to me with a new blank one, and we just get to go back and forth. And I thought that that was really nice, and she colored it while she was in class. So I'm gonna color mine while I'm in class probably. And I just think that that's so sweet.
Jam:How fortunate that the stars aligned for you and I to share about things that Each other would not understand in the slightest.
Melissa:You don't understand someone sending you a nice gift in the mail?
Jam:I under yes. Yeah. Yeah. Okay. That's about where
Melissa:It is.
Jam:Yeah. That's where I after that, I got lost.
Melissa:Well, my sister
Jam:I looked getting letters too.
Melissa:And I
Jam:was like, yep. I'm with you. I'm with you. And then Once it got to the contents and all that stuff. Yep.
Jam:But it's okay though, because the email thing, you're probably, like, what the heck? That's not cool. I would not have fun doing that.
Melissa:Mhmm.
Jam:So the stars aligned, and we Right. Both were able to share about those kind of things at the same time.
Melissa:I do understand the satisfaction of having something taken care But, yes, I I never would have shared about that. But my sister and I do share a love of true crime, and so it's fun. And I thought it was just so sweet that She thought of me while she was doing that in her class. That's so nice.
Jam:That is nice. Being thought of by someone else is nice. And being receiving a letter from them is nice.
Melissa:That's true. Yeah. Thanks, Jam. And thanks to you guys for listening and hanging out.
Jam:Mohsen and I have a lot of ideas for topics of chemistry in everyday life, but we wanna hear from you. So if you have questions or ideas, you can reach out to us at Gmail, on Twitter, Instagram, Facebook at chem for your life. That's fem, f o r, your life, to share thoughts and ideas. If you enjoy this podcast, you can subscribe on your favorite podcast app. If you really like it, tell 1 friend about our podcast.
Jam:They that you think that they would they would like it, and that would it'll bring some joy into their life we can share chemistry with even more people.
Melissa:That's always my goal. Mhmm. If you'd
Jam:like to help us keep our show going and contribute to cover the costs of making it, Go to kodashfi.com/chem for your life, and donate the cost of a cup of coffee.
Melissa:This episode of Chemistry For Your Life was created by Melissa Colini and Jame Robinson. References for this episode can be found in our show notes or on our website. J. M. Robinson is our producer, and we'd like to give a special thanks to a Colini and Anne Newell who reviewed this episode.
