Nearly every shopper and cook wants to ensure that they’re going to be able to prepare meals that are not just tasty and healthy, but also safe and delicious, so what does it mean if apples are already brown on the inside, or if they turn brown quickly after purchase?
Apples turn brown due to oxidation. When apples are bitten, cut, or bruised, cells are broken, and enzymes mix with compounds. Oxygen in the air starts a chemical reaction where the apple browns but is still safe to eat. However, the shelf life of brown apples is short.
So, now we know the apple is not contaminated at all, just changed. What does this change in the apple mean, and how can we prevent browning in apples in case we want to make the fruit last even longer? Let’s look at the facts and food science of apples, so we know what to do the next time we buy apples or cut into them.
Why Apples May Be Browning on the Inside
Over time, apples can turn brown internally before it even gets sliced into and exposed to oxygen. When cutting into an unbroken apple, you might see some brown spots that have been growing and spreading into the flesh of the fruit.
Sometimes internal browning happens thanks to cold storage, CO2 damage, calcium deficiencies, as well as oxidation. This is more likely to happen the longer the apple has been on the shelf. The apple is still alright to eat, but it may be best to cut off these brown splotchy areas, as they are often unpleasant in taste and mushy in texture.
Why Do Apples Turn Brown?
Apples turn brown because of oxidation. As soon as an apple is bitten into, sliced open, or bruised, this process begins. This is because the cells in the apple get broken into, and the enzymes of polyphenol oxidase in the apple chemically react with the oxygen in the air. This chemical combination is what makes the apple turn brown.
This process can be called oxidation or enzymatic browning, similar to what happens in other natural foods, such as peaches, pears, bananas, apricots, potatoes, and lettuce. This enzymatic browning even happens in wheat, flour, or rice cereals and in shrimp, lobster, and crabs.
The apple compounds that mix with oxygenated air are all doing these things for a scientific reason. These compounds defend themselves from harmful microbes or attacking insects.
This preventative and defensive measure isn’t going to harm you when you eat the apple, but it will shorten the shelf life of the apple, so it’s best not to cut into an apple and then leave it on a counter for a long time. There are, luckily, a few ways to keep apples from browning after they are cut.
Here’s another article you might be interested in: Spots on Tomatoes | What Do They Mean?
Are Brown Apples a Health Hazard?
Brown apples are not almost never hazardous to your health because browning is not a sign that bacteria is growing on the food. Browned or slightly discolored apples can be enjoyed and eaten all the same. However, many people don’t like eating brown apples because they feel they aren’t eating fresh food.
How to Prevent Sliced Apples from Turning Brown
The simplest way to stop apples from turning brown is by coating or soaking your sliced apples in some lemon juice. The enzymatic browning mentioned before will only happen at a pH level that is between 5 to 7. Lemon juice has a pH level of 2 and will create a protective wall around the apple’s skin and flesh. Lemon juice also sucks up oxygen into itself, further helping to stop the oxidation browning process.
Some people dislike the lemon flavor that bathing apples in lemon juice will often create. To avoid this, some experts advise people to crush up vitamin C tablets into a powder, dissolve it in water, and dip apple slices into the mixture to prevent browning.
Even using temperature changes can help. Putting apples into a fridge slows down the browning process.
Bringing the apples to a high enough temperature will even reconfigure the browning enzyme, which will also prevent enzymatic browning from happening. Heating the enzymes will “denature” them and stop the process, so apples can be cooked or blanched in hot water until the enzymes are swiftly reconfigured and stopped.
Pro Tip: Browning can be halted by insulating the apples from oxygen in the first place. This can easily be done by storing apples in a bowl of cold water and by coating them with sugar, honey, or syrup.
Coating apple slices this way will create a protective shield and barrier between the fruit and the oxygen in the air. Sprinkling apples with some cinnamon can even help, since it disguises the brown discoloration, and adds a nice flavor to the aged fruit.
Other Ways to Prevent Browning in Apples
Some additional materials that stop apple browning include vinegar, honey, salt, water, vitamin C, and baking soda. After this testing of various preventatives, it turned out that lemon juice and vinegar did not work so well on the apple slices, while the salt seemed to prove most powerful in preventing browning.
Not recommended: Although a saltwater mixture may best stop apple browning, it may alter the flavor negatively, so stick to temperature control, bowls of water, and light lemon juice baths.
While browning in apples is often seen as negative and unappealing aesthetically, this enzymatic browning is actually sought after in some other foods. For instance, this chemical reaction helps to add pleasing, deep brown colors to substances like tea, coffee, and chocolate.
Another fun fact is that scientists have been working on genetically engineering apples that won’t ever brown. These apples aren’t on the market yet but may very well be put into circulation in grocery stores and markets soon.
Below is a great video that covers what has been discussed so far, about why apples brown, the science behind it, and other ways to stop this enzymatic browning in its tracks so you can enjoy crisp, non-brown apples.
Thanks for stoppin’ by!
For more, don’t miss 12 Delicious Things To Do With Leftover or Overripe Pears.
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