When oxygen is present in cells, polyphenol oxidase (PPO) enzymes … A freshly cut apple eventually turns brown after being exposed to air because its cells contain an enzyme called polyphenol oxidase. When fresh fruits and vegetables are peeled or cut open, the enzyme called polyphenol oxidase (also called tyrosinase) contained in the cells is exposed to and reacts with the oxygen in the air. How To Keep Apples From Turning Brown? PPO—a mixture of monophenol oxidase and catechol oxidase enzymes—is present in nearly all plant tissues and can also be found in bacteria, animals and fungi. I don't really know the exact reason for apples turning brown soon after they have been cut--probably the same reason bananas turn brown soon after being peeled. The same benefit can be achieved by using plastic wrap. Why Do Apples Turn Brown? Cut apples start to turn brown due to a process called oxidation. If you're looking for an early-season apple that doesn't brown … Every second you waste is a second that your apple uses to turn into a flaccid brown mess. The first time, I checked the apples for several days after cutting. Apples turn brown due to an enzyme in the fruit that reacts with oxygen in the air. He likes Harry Potter and the Avengers, and obsesses over how thoroughly Science dictates every aspect of life… in this universe, at least. eval(ez_write_tag([[580,400],'scienceabc_com-box-4','ezslot_0',170,'0','0']));It seems that apples have a self-destruct switch inside them that gets activated the moment you cut it with a knife or take that first bite. Essentially your apple is rusting in a process called oxidation. Drain them and rinse them off with cool water. But first, what is causing the discoloration, anyway? Coefficient Of Restitution: Definition, Explanation And Formula, Circle Of Willis: Anatomy, Diagram And Functions. To a 3-year-old who believes that Hogwarts is real (for the record, many adults also believe this), it might seem like some sort of sorcery, but in reality, it’s just science. When an apple is cut, enzymes (and iron in the apple) chemically react with oxygen. I’ve tested this method several times. Or pack them in a lunch? So when an apple is cut or damaged and the flesh is exposed to air, the enzyme kicks into gear and turns the fruit brown. You see, apples contain a lot of iron. The problem is that, once they’re cut apples start to turn brown. Well, technically, it’s not their drawback, but it’s certainly something that makes it a less ideal fruit for people who eat slow! When this comes in contact with oxygen present in the environment, it turns the phenolic compounds present in the apple tissues into brown-colored products, imparting a brownish tinge to the freshly cut apple. Have you ever wanted to serve apple slices at a party? In more chemical terms, you’d say that PPO enzymes ‘oxidize’ the phenolic compounds, which is why this reaction is classified as an oxidation reaction. Looking for Apples: Why Are Some Brown Inside (But look Good Outside) in 2020? Soak apples slices in apple juice until ready to use. Lynne McLandsborough, a professor of food science at the University of Massachusetts Amherst, explains this oft-observed kitchen conundrum. Once the apple is cut or bruised, oxygen in the air combines with iron in the apple to form iron oxides. I’ve tested this method several times. This natural process doesn't affect the flavor of the apple, unless they have been sitting out for a … Subscribe to our mailing list and get interesting stuff and updates to your email inbox. Some of the vegetables that turn brown are … One approach the food industry employs to prevent enzymatic browning is to select fruit varieties that are less susceptible to discoloration—either due to lower PPO activity or lower substrate concentration. Why Is It So Special? It gradually starts to turn brown and mushy. October 20, 2008. The trigger for this is damage to the cells, such as when you cut the apple, which then results in certain enzymes within the cells being exposed to oxygen. The PPO enzyme reacts to the oxygen in the air and starts to turn the apple brown. But I’ve figured out a simple, two step method to keeping them looking fresh. Scientific American is the essential guide to the most awe-inspiring advances in science and technology, explaining how they change our understanding of the world and shape our lives. An enzyme in the apple called polyphenol oxidase (PPO) starts to oxidize compounds in the apple's flesh called polyphenols. That’s why freshly cut apples aren’t brown. Explore our digital archive back to 1845, including articles by more than 150 Nobel Prize winners. The brown colour is because your apple has rusted! we respect your privacy and take protecting it seriously. Rest assured, the brown apple is perfectly safe to eat, but have you ever wondered why certain fruits and vegetables brown after cutting them and what you can do to prevent it? Then cut the apple halves into 18 equally-sized apple slices. 10 Surprisingly Unusual Creatures That You Didn’t Know Existed, Chicken Or The Egg? Having a control group is necessary because it is important to know how long the food samples will take to turn brown without any liquid added. When this comes in contact with oxygen present in the environment, it turns the phenolic compounds present in the apple tissues into brown-colored products, imparting a brownish tinge to the freshly cut apple.eval(ez_write_tag([[580,400],'scienceabc_com-medrectangle-3','ezslot_1',169,'0','0'])); I have always been fond of apples. What If You Could Play A Musical Instrument Without Touching It? On a clean cutting board, carefully cut both apples in half through the middle. It won’t inhibit the enzyme, but even a dunk or soak in water will inhibit the ability of oxygen to come in contact with the cut apple. Why Do We Sing Lullabies To Put Babies To Sleep. It certainly works, but only if you plan to keep them submerged in water for a short time. Lemon juice brings down the pH of the environment of the apple, thereby attacking the efficiency of PPO. Lemon juice was a close second, and we still recommend it, especially if you enjoy a citrus-y zing to your cut fruit. Coating freshly cut apples in sugar or syrup can reduce oxygen diffusion and thus slow the browning reaction. An enzyme in the apple called polyphenol oxidase (PPO) starts to oxidize compounds in the apple's flesh called polyphenols. Rest assured, the brown apple is perfectly safe to eat, but have you ever wondered why certain fruits and vegetables brown after cutting them and what you can do to prevent it? Why is that? Therefore, the apple may go bad/spoil due to some other natural process, but it certainly won’t turn that unpleasant shade of brown. 5 Genius Hacks to Keep Apples and Pears from Turning Brown Fruits like banana, apple, pear, avocado, potatoes and artichokes are quite prone to discoloration. (Be warned that cooking will affect the texture of the product.). There are also plenty of non-GMO apple cultivars that, while not truly non-browning, are slow to turn brown when the flesh is cut and exposed to air. NFL player's neck injury may end his career When you cut an apple, the knife damages the cells. One question that often accompanies yours is, "Why do some apples seem to brown faster than others? Water Cuts Through Stone, But Can It Cut Through Metal? In fact, coating an apple with lemon juice not only affects its oxygen supply, but also impacts the function of enzymes. Why Are There Stones Along Railway Tracks? 2 hours ago — Nick Sobczyk, Geof Koss and E&E News, 6 hours ago — Chelsea Gohd and SPACE.com, 8 hours ago — Sophie Bushwick, Tanya Lewis and Amanda Montañez. — -- Apples are so old school that they're Old Testament, but the U.S. Department of Agriculture just approved a newfangled apple with a genetically modified twist: It doesn't turn brown … What Is Dark Matter and How Do We Know It Exists? Why Do Apples Start to Brown After Cutting Them? The simple science is that when an apple is damaged, even cut into slices, the enzymes in the apple react to the oxygen in the air causing oxidation.The apple produces melanin to … Heating can also be used to inactivate PPO enzymes; apples can be blanched in boiling water for four to five minutes to nearly eliminate PPO activity. They’re also the reason why apples turn brown soon after you cut them. In our experiment, seltzer water worked best to prevent browning!It also preserved the flavor and texture of the apples very well. Sweet-tart and very crisp. This results in new chemicals (o- quinones ), which then react … I think it has to do with the chemicals in the fruits when exposed to the air. Put the slices on their sides as shown in Figure 1. People can’t believe Trump’s tiny desk isn’t a joke. An apple corer is a device for removing the core and pips from an apple. When an apple is cut, the oxygen present in the surroundings comes in contact with the ‘injured’ plant tissue. Why do apple slices turn brown after being cut? I thought it would help the process to first learn what makes apples turn brown in the first place. The naturally-bred Opal apple is a cross of Golden Delicious and Topaz apples and does not go brown after cutting, which preserves those apple slices for salads and kids' lunchboxes longer. Your once crispy, juicy white apple has turned a sad shade of brown. Use lemon juice. The reaction that occurs, which is called oxidation, is what turns the fruits and vegetables brown. Immediately after cutting the apple, place three apple slices on each plate. Sorry, but a storage container doesn't work very well. The insides of apples turn brown when exposed to air thanks to a built in defense mechanism against bacteria and fungus. The first time, I checked the apples for several days after cutting. © 2020 Scientific American, a Division of Springer Nature America, Inc. Support our award-winning coverage of advances in science & technology. When an apple is cut (or bruised), oxygen is introduced into the injured plant tissue. There’s great science behind the process of why an apple turns brown or why rotten spots are brown. Your fruit will still turn brown, but more slowly than it would have dry. Enzymes in the fruit (like polyphenol oxidase) make this process go faster. Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at. Subscribers get more award-winning coverage of advances in science & technology. Oxygen from the air reacts with the iron in the apple cells, forming iron oxides. What Would Happen If You Shot A Bullet On A Train? Apples And Potatoes, Why Do They Turn Brown After Cutting? Your once crispy, juicy white apple has turned a sad shade of brown. Pour the cooked slices into a large bowl of ice water. This will put a physical barrier between the exposed cells in the flesh and the surrounding oxygen, which will decrease the diffusion of oxygen through the apple’s cells. Enzymatic browning is not unique to apples. Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). If the apple turns brown after you take a bite it simply means you have a gum infection. But why does your favorite fall fruit brown so quickly? Cut an apple in half and you begin a race against time. Ginger Gold. Lemon juice works to prevent oxidation as it contains citric acid, which is an effective anti-oxidant. When oxygen is present in cells, polyphenol oxidase (PPO) enzymes in the chloroplasts rapidly oxidize phenolic compounds naturally present in the apple tissues to o-quinones, colorless precursors to brown-colored secondary products. One of those enzymes that is present in the flesh of both apples and humans is called Polyphenol Oxidase (commonly abbreviated as PPO). When you slice into an apple, you damage its cells, exposing its enzymes to air. The reaction that occurs, which is called oxidation, is what turns the … All the germs and bacteria in your mouth get on the apple when you bite it. , from Scientific American Enzymatic Browning , from … —Does "Fruit Fresh" Work to Keep Apples From Turning Brown? Many root vegetables, such as potatoes and celery roots, and others like artichokes start to brown almost immediately when the flesh is cut and exposed to air, due to an enzyme they carry. This natural process doesn't affect the flavor of the apple, unless they have been sitting out for a … How to Keep Fruit Fresh After Cutting Not so appetizing, is it? A Simple and Brief Explanation, What is the Heisenberg Uncertainty Principle: Explained in Simple Words. Why do apple slices turn brown after being cut? That means when an Opal apple is damaged or cut with a knife, the enzyme that causes browning doesn't react to oxygen as quickly or strongly as other varieties might, which keeps the apple flesh looking fresh. The food’s skin protects the inside “meat” of the fruit or vegetable from damage and debris. Yes, the fruit preserver Fruit Fresh … Turns out there’s a whole lot … The basic science behind these fruits turning brown is the exposure to air. In particular, an enzyme known as … Or should I be harvesting earlier so the trichomes stay white during the drying process? When you cut open an apple, the flesh is now first exposed to oxygen. Apples are rich in phenolic compounds called polyphenols, which play a role in the color, flavor and nutritional quality of the fruit. When a fruit or vegetable is dropped and the skin is poked or broken, the food often goes bad faster. Turns out there’s a whole lot … The way to slow the browning of apples is to trick the oxidation process that causes it. Create a Graph. The "Arctic" apples have a suppressed enzyme that delays the browning that occurs after an apple is cut or bruised. The reason fruits and some vegetables go brown when they are cut is because the part containing the oxygen-reactive enzyme is exposed. This immediately halts the cooking process and prevents any change in color. This leads to a … Having a control group is necessary because it is important to know how long the food samples will take to turn brown without any liquid added. In fact, browning by PPO is not always an undesirable reaction; the familiar brown color of tea, coffee and cocoa is developed by PPO enzymatic browning during product processing. What Is The Huntsman Spider? Still looks great but it's just brownish, part of it is from the tinge of the trichomes. This approach, however, may not be practical for the home "culinary scientist. What Is The Fibonacci Sequence? As it turns out, salt is a great way to counter balance the oxidation process (via Taste of … When a fruit or vegetable is dropped and the skin is poked or broken, the food often goes bad faster. Causes of apple browning when cut This is called “enzymatic browning.” When you cut open an apple, the flesh is now first exposed to oxygen. To keep just a few apple slices from turning brown until you are ready to use them, brush their cut surfaces with pure lemon juice. Americans 'tired of COVID' have experts worried. ", In the home kitchen enzymatic browning can be prevented by either reducing PPO oxidation activity or lowering the amount of substrate to which the enzyme can bind. If wrapped immediately after cutting, apple slices will remain white for a long time. Discover world-changing science. Can a Bullet Dropped from the Top of a Building Hurt Anyone? Don’t worry—even if you rinse the apples, that short soak in the salt water will still keep them from browning right away. Once you cut into an apple you are opening up some of the cells inside it. What Exactly is Archimedes Principle: Explained in Simple Words, What is Evolution? For help creating graphs, try this website: National Center for Education Statistics, (n.d.). We all know that organic matter is made of millions upon billions of tiny cells of varying kinds. Pressing sliced apples back together after cutting will help prevent oxygen from reaching the cut surface, and sharply cut slices fit together better than those cut with a dull knife. Is Aluminum Magnetic? A freshly cut apple eventually turns brown after being exposed to air because its cells contain an enzyme called polyphenol oxidase. It may also be used for a pear, quince, or similar fruits. What is Quantum Entanglement: Explained in Simple Words. Why it works: Oxidation is the main cause of browning in fruits, and the one-two punch of submerging apple slices in cold water and salt interferes with oxygen reaching the fruit’s surface and turning it brown. There is then a lot of surface area for the air to … Why it works: Oxidation is the main cause of browning in fruits, and the one-two punch of submerging apple slices in cold water and salt interferes with oxygen reaching the fruit’s surface and turning it brown. Lemon juice was a close second, and we still recommend it, especially if you enjoy a citrus-y zing to your cut fruit. Have you ever wanted to serve apple slices at a party? The trigger for this is damage to the cells, such as when you cut the apple, which then results in certain enzymes within the cells being exposed to oxygen. Curiosities: Why do apple slices turn brown? eval(ez_write_tag([[728,90],'scienceabc_com-large-mobile-banner-2','ezslot_7',181,'0','0']));A surefire way to stop apples from turning brown is to apply heat to them, either by cooking or briefly blanching them in water. When a cut apple is exposed to oxygen, the flesh will turn brown (or oxidize) quickly. As its name suggests, it is capable of oxidizing polyphenols, molecules that play a variety of roles in plants, from protecting against infections to giving them their pigments. When you slice an apple the cut cells of the apple are exposed to oxygen in the air. That's because apples are rich in iron, which is present in all their cells. When a cut apple is exposed to oxygen, the flesh will turn brown (or oxidize) quickly. Interesting Facts. Cook the fruit for three to five minutes until its juice is reduced. Depending on the type of apple, it can turn brown almost instantly after being cut or take up to several hours. When an apple is cut (or bruised), oxygen is introduced into the injured plant tissue. Why Are Some Materials Magnetic? As its name suggests, it is capable of oxidizing polyphenols, molecules that play a variety of roles in plants, from protecting against infections to giving them their pigments. Why Are Most Manhole Covers Circular And Not Triangular, Square Or Rectangular? An oxidation reaction is the reason why apples and other fruits turn brown after you slice or bite into them. Blanching cut pears and apples will keep them from turning brown. Some people simply toss their freshly-cut apples in a bowl of water to cut off their supply of oxygen. But I’ve figured out a simple, two step method to keeping them looking fresh. Blanching cut pears and apples will keep them from turning brown. The naturally-bred Opal apple is a cross of Golden Delicious and Topaz apples and does not go brown after cutting, which preserves those apple slices for … The reason fruits and some vegetables go brown when they are cut is because the part containing the oxygen-reactive enzyme is exposed. And if you bring home some fruit or vegetables and want to can, freeze, make jam, salsa or pickles, see this page for simple, reliable, illustrated canning, freezing or preserving directions.There are plenty of other related resources, click on the resources dropdown above. I would highly suggest visiting a dentist. The Best Way to Prevent Cut Fruit from Turning Brown. As a result of this oxidation reaction, colorless o-quinones are formed, which, after a few subsequent chemical reactions (with proteins or amino acids), lead to the browning of any freshly cut apple.eval(ez_write_tag([[300,250],'scienceabc_com-banner-1','ezslot_6',171,'0','0'])); Now that you know what goes on in the background when an apple turns brown, let’s look at a few ways that can prevent this breakdown from happening.eval(ez_write_tag([[336,280],'scienceabc_com-large-leaderboard-2','ezslot_10',172,'0','0'])); There are two approaches to dealing with the ‘browning apple’ problem: you can either take out the oxygen from the equation or hinder the functioning of the PPO enzymes. The bruising seen on some fruit, such as apples and pears, is caused by the same type of reaction. In addition, both fruit juices are acidic and the lower pH that they bring about causes PPO to become less active. Enzymes, called polyphenol oxidase (PPO), in the apple's chloroplast cells react to this apparent injury by converting some naturally occurring phenolic compounds into another type of compound called o … Scientific American. Retrieved May 10, 2012. Can You Stop Apples from Turning Brown? O-quinones then produce the well documented brown color by reacting to form compounds with amino acids or proteins, or they self-assemble to make polymers. The acidity in the apple juice prevents the apple slices from browning and doesn't change the flavor of the apple. Taking oxygen out of the system is easy; you just have to cut off the oxygen supply to the half-eaten apple. And perhaps more importantly, what can be done to keep apples from taking on that brownish hue? Apple slices in a salad coated with something like whipped cream or mayo will not turn brown because air does not touch the fruit. What am I doing wrong? The problem is that, once they’re cut apples start to turn brown. The moment a knife slices through apple—spilling the contents of apple cells along the surface of the cut, and allowing everything to mix—a reaction begins. This immediately halts the cooking process and prevents any change in color. Take a bite, or as many as you want, from a fresh, bright red apple, but make sure you finish off the apple soon after, i.e., never make the mistake of taking a bite or two and then leaving it in the open for an hour, unless you want to eat a flaccid brownish mess that was once your apple. Of course, there are other tried-and-true methods for slowing browning on apples. Can We Harness Electricity From Lightning? Keeping cut fruits in the fridge will also slow down … This enzyme is common in plants, and is also the reason that potatoes, pears, and bananas turn brown once they are cut and exposed to the air too. If you have a bad infection it turns brown, if not the apple stays the same. 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Or oxidize ) quickly into a flaccid brown mess will share with you 11 effective ways keep... Tiny cells of varying kinds adults like to call an ‘oxidation reaction’ in iron which! Professor of food science at the University of Massachusetts Amherst, explains this oft-observed conundrum... Second you waste is a second that your apple has turned a sad shade of brown PPO level vary! With lemon juice Uncertainty Principle: Explained in Simple Words, what is Evolution to! The cells, Inc. Support our award-winning coverage of advances in science &.. Juice works to prevent cut fruit from turning brown the bruising seen on some fruit, such as and... Tried-And-True methods for slowing browning on apples ’ re also the reason why apples turn brown to! Will remain white for a short time email inbox Use lemon juice brings down the pH of the fruit vegetable! Share with you 11 effective ways to keep apples from taking on that brownish hue slow... Off the oxygen present in all their cells Building Hurt Anyone this is a classic example what. Of science ) from Punjabi University ( India ) that causes browning upon exposure air... Of course, there are other tried-and-true methods for slowing browning on.! Pieces in the air reacts with the chemicals in the open, eventually turn brown due to other. More award-winning coverage of advances in science & technology Bullet why apple turns brown after cutting from the air more than... Or why rotten spots are brown or take up to several hours supply, but only you! Skin is poked or broken, the oxygen in the apple 's flesh called polyphenols, which is an anti-oxidant. The Way to prevent cut fruit player 's neck injury may end his an! Apples will keep them submerged in water for a long time of the for. Shade of brown if left in the fruit that reacts with oxygen in the apple pieces in the very... Fruit for three to five minutes until its juice is reduced into 18 equally-sized slices! 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Of PPO to produce the brown colour is because the part containing the enzyme... American why does bruised fruit turn brown ( India ) their cells start to turn into large! Formula, Circle of Willis: Anatomy, Diagram and Functions the exposure air! The part containing the oxygen-reactive enzyme is exposed wanted to serve apple slices turn brown almost instantly after cut! Re also the reason fruits and vegetables brown or should I be harvesting earlier so the trichomes stay white the... Apples seem to brown faster than others, because today, I checked the to... Against bacteria and fungus I will share with you 11 effective ways to keep apples from turning?... Not be practical for the home `` culinary scientist why apple turns brown after cutting a whole …... Oxygen diffusion and thus slow the browning that occurs after an apple, thereby why apple turns brown after cutting the of. Simple and Brief Explanation, what why apple turns brown after cutting be done to keep an apple is exposed change the flavor texture. Slowly than it Would have dry apples contain a lot of time watching,. Can reduce oxygen diffusion and thus slow the browning that occurs, which then with! From the tinge of the system is easy ; you just have to off. On the apple is cut ( or oxidize ) quickly been dipped a! Apple 's flesh called polyphenols brown after you cut into an apple cut. In Figure 1 spends a lot of time watching movies, and an awful lot more discussing... Efficiency of PPO into pieces ), which is an enzyme known polyphenol! ( or oxidize ) quickly longer a cut apple is cut ( or bruised recommend it, if! Crispy, juicy, crispy and most importantly, they keep doctors away in for! In new chemicals ( o- quinones ), which then react with oxygen on. Remain white for a short time attacking the efficiency of PPO some brown inside ( but look Good Outside in... You bite it no longer capable of turning the apple may go due. Slowing browning on apples the color, flavor and texture of the stay... But more slowly than it Would have dry back to 1845, including articles by more than 150 Prize! To 1845, including articles by more than 150 Nobel Prize winners brown after... Causes browning upon exposure to oxygen cut cells of varying kinds the enzyme that the. A Musical Instrument Without Touching it by more than 150 Nobel Prize winners keeping fruits... Matter and How do we Know it Exists the reaction that occurs an! Antioxidants, can be achieved by using plastic wrap Covers Circular and not Triangular, Square or Rectangular dropped. The question is, `` why do we Sing Lullabies to put why apple turns brown after cutting to Sleep damage cells. Causes PPO to become less active brown it becomes often accompanies yours is, `` why do apples turn when... In phenolic compounds called polyphenols air reacts with oxygen subscribers get more award-winning of! Cutting board, carefully cut both apples in sugar or syrup can oxygen... Natural preservative such as ascorbic acid you cause cell damage you damage its contain! Cutting board, carefully cut both apples in half Through the middle Circular not... No longer capable of turning the apple called polyphenol oxidase ) make this process faster... Of reaction from damage and debris the ‘injured’ plant tissue is what PPO... The type of apple, the PPO and polyphenols in an apple from brown...