How to Keep Lunchbox Apple Slices From Turning Brown (So Your Kids Will Actually Eat Them)

It’s back-to-school season, and you know what that means: We're back to packed lunches. It’s also time to unearth tips and tricks that make assembling them less of an early-morning hassle.

For generations, a good ol’ bag of apple slices has been a lunchtime staple. I remember opening up my bag as a kid to find a plastic baggie full of thinly sliced apples, tossed in some sort of preservative to keep them from browning. Though crisp and delicious, we’ve come a long way from coating the natural with the unnatural.

Recently, I learned the trick of squeezing lemon on a cut apple to keep it from turning brown. Curious as to why it works, I consulted an expert.

Why Do Sliced Apples Turn Brown?

I talked to Veronica Tegen, the CEO of The Food Geek and board member of the Midwest Fruit Explorers.

“Apples turn brown when cut because of an enzyme in their flesh that reacts with oxygen,” she explains. “When the enzyme oxidizes, it creates melanin.”

According to Tegan, not all apples brown equally. For example, Cortland, Empire, Cameo, and Gala will brown more slowly because their flesh contains less of this reactive enzyme. However, every variety will start to brown at some point if left untreated.

How To Keep Apple Slices From Browning

Tegan shared three ingredients that will mitigate browning (citrus, honey, and salt), all of which slow oxidation by removing the apple's exposure to air and countering the enzyme. However, each one works in a slightly different way.

She explains that acidic ingredients, such as lemon juice, change the apple's pH to slow down the reaction; salt breaks up the enzymes that turn apples brown; and honey solutions coat the apples, which prevents oxygen from interacting with the apple's cut surfaces.

My colleague has written about using salt before, swearing by a saltwater solution to keep her apples crisp and white. I respectfully opt for the lemon alternative. Why? Well, because in my experience, no matter how much I rinse off a saltwater solution, I’m still left with a salty aftertaste. Lemon, on the other hand, adds an extra bit of sharpness to the apples.

How To Use Lemon Juice To Stop Browning

Tegen advises soaking cut apples in a solution of one-half to one tablespoon lemon juice per cup of water for no more than 30 minutes. However, one reason I prefer lemon over other soaking methods is that in a pinch, you can squeeze a lemon half over the slices, toss until coated, then throw them in a resealable bag. How's that for a slice of wisdom?