The moment you cut into an apple, the clock starts ticking. As the minutes pass, the fruit’s once-pristine interior starts to brown, giving your carefully sliced snack or iconic pie ingredient a very different hue. What gives?

To understand why apples brown and the best ways to keep them from changing color, we consulted a food scientist. Here’s everything you need to know.

How to prevent apples from turning brown

You can’t entirely prevent apples from browning over time, but you can slow down the process. Oxygen is the enemy here. “Either create a protective barrier or add an ingredient to slow down oxidation,” says certified culinary scientist Jessica Gavin. “Each of these methods helps maintain the apples’ color and freshness, making them perfect for prepping ahead.”

1. Submerge cut apples in cold water

Add apple pieces to a bowl filled with cold water. Place a paper towel directly onto the surface of the water to keep the slices submerged. Plan to use them within 12 hours of cutting for peak freshness. “It’s simple, economical, and effective for same-day use,” Gavin says.

2. Soak cut apples in salted water

Mix half a teaspoon of salt with one cup of cold water, stirring until the salt mostly dissolves. Soak the apple pieces for 10 minutes, then drain and rinse them in fresh, cold water. 

“I prefer the salt water method for long-term storage,” Gavin says. “It’s great for prepping ahead, keeping apples bright and fresh with minimal impact on taste or texture, even after 24 hours.”

3. Briefly soak cut apples in lemon water 

Mix one teaspoon of lemon juice with one cup of cold water to make acidulated water. Soak the apple pieces for five minutes, then drain them and rinse in fresh cold water. Gavin suggests using them within 24 hours. You can also simply rub the apples with fresh lemon juice, as many apple pie recipes suggest. 

4. Briefly soak apples in sweetened water

Honey contains a compound that neutralizes polyphenol oxidase, an enzyme that contributes to fruit browning. Add a tablespoon of honey to one cup of cold water, and stir vigorously until it dissolves. Soak the apple pieces for five minutes, then drain them and give them a rinse in fresh cold water. Use them within 24 hours. 

Why do apples brown?

Apples brown after they’re cut because oxygen initiates a chemical reaction in the newly exposed flesh.

“When you cut into an apple, you break its cell walls, releasing an enzyme known as polyphenol oxidase,” explains Gavin. “When exposed to oxygen, this enzyme reacts with [compounds known as] polyphenols in the apple’s flesh.” The resulting chemical reaction forms brown pigments called melanins. 

Apples usually start to brown within 15 minutes of being cut. If the room where the sliced apples are sitting is very hot, browning can occur more quickly.

Certain types of apples brown more quickly than others. Fuji, McIntosh, and Golden Delicious generally brown faster than Honeycrisp; while Empire, Pink Lady, and Cortland apples are the slowest to brown.

Can you eat brown apples?

It’s perfectly safe to eat apple slices that have turned brown. You might not find them as visually appealing as when they were freshly cut, but the oxidation process doesn’t change apples’ flavor or indicate spoilage.