Blog

Oct 18, 2024

How to Keep Apples From Browning, According to Experts

Keep your apples brighter for longer with these pro tips. Kirsten Nunez is a writer who focuses on food, health, nutrition, and DIY. She has a master's degree in nutrition, and has been writing

Keep your apples brighter for longer with these pro tips.

Kirsten Nunez is a writer who focuses on food, health, nutrition, and DIY. She has a master's degree in nutrition, and has been writing professionally for nearly 10 years for digital and print publications, such as Martha Stewart, Shape, Real Simple, Healthline, and SELF. She also creates original recipes, which have appeared on product packaging in stores.

Getty Images

Whether you're packing a snack, arranging a grazing board, or baking pies, there are plenty of reasons to stock up on apples. The only catch? Apples are notoriously difficult to store once cut, as they quickly turn brown. Unfortunately, it's not possible to completely stop this browning—but it can be delayed. Learn the different ways to slow down browning in freshly cut apples, including the best overall method, according to experts.

"Apple cells contain an enzyme, polyphenol oxidase (PPO), that's only active once the apple's flesh is exposed to oxygen," explains Rosemary Trout, program director and assistant clinical professor of culinary arts and food science at Drexel University. This can happen when the apple is sliced, peeled, or bruised, she adds. The reaction increases the production of melanin, a pigment that creates the brown color in apple flesh.

Though unsightly, apple slices that have browned are still safe to eat, says Bryan Quoc Le, PhD, food scientist, food consultant, and author of 150 Food Science Questions Answered. That's because the enzymatic reaction that causes browning doesn't affect the safety (i.e., level of harmful microorganisms) in the apple.

However, cut apples that have been stored in water can become mushy over time. This is worth keeping in mind, especially if you dislike certain textures.

Dipping cut apples in salt water is the best way to delay browning, says Kimberly Knight, chef-instructor at the Institute of Culinary Education.

It works because salt has a low oxygen solubility, which further prevents PPO from accessing oxygen, says Trout. Plus, the salt content "causes the enzyme to undergo a process known as denaturation, resulting in deactivation," shares Le.

To use salt water, follow these steps from Trout:

How long it lasts: Salt water can delay browning for about 12 hours. The cut apples won't taste like salt, but you can quickly rinse them off if you're concerned about a salty flavor.

If you don't want to use salt water, there are other ways to slow down the browning reaction in cut apples.

Here's how to use plain water, according to Knight:

"Apples in plain water will retain their crunch and taste for up to six hours before they'll start to brown," says Knight.

Another method is to apply lemon juice directly on the apples. The acidity of the lemon juice will lower the pH of the apple, which decreases PPO activity, says Trout.

"Additionally, lemon juice contains a high concentration of vitamin C, or ascorbic acid, which readily reacts with oxygen and removes [it] from the surface of the apple," explains Le. "This helps prevent the production of brown compounds from the enzymes, he adds.

Follow these steps to use lemon juice to delay cut apples from browning:

This method can delay browning for about seven hours, according to Knight.

If you enjoy the tart taste of lemon juice on apples, feel free to skip the rinsing step.

You can also keep cut apples in a mixture of water and lemon juice. As mentioned above, lemon juice will reduce the activity of PPO and decrease oxygen exposure.

To use lemon water, follow these steps:

Typically, this technique will delay browning for two to three hours.

Another technique is to soak the cut apples in sugar water. Sugar, like salt, prevents PPO from accessing oxygen, according to Trout.

Here's how to use this method:

You can also use honey instead of sugar, but sugar is much more cost-effective.

If you plan to use cut apples for baking, try blanching them first. The heat will deactivate the PPO in the apples, helping slow down browning.

If you don't plan to eat the cut apples right away, store them in the refrigerator after using any of these methods. The low temperature inside the fridge will slow down the activity of PPO, further delaying browning. Be sure to place the apples in an airtight container first to reduce oxygen exposure.

Le adds that refrigeration slows down the growth of harmful bacteria on the apple's flesh and reduces the chances of mold.

For best results, he recommends eating the apples within three to five days.

If your cut apples have mold or a slimy texture, it means they've gone bad, says Le. You should also toss the apples if they have an odor that's earthy, musty, or alcoholic.