Buzz
Fruit and veggie slices are a tasty, nutritious snack, but the browning and mushiness that can occur with some fruits can be discouraging. This is a common problem, and there are countless ways to tackle it online. But it’s difficult to know which methods are worth your time. Fortunately, I’m here to guide you through the best options.
The brown blemishes on fruit are essentially ‘fruit rust,’ created when oxygen in the air interacts with an enzyme known as polyphenol oxidase. This article dives deeper into the science, but to stop the browning process, you must either block the oxygen or the enzyme (or both). Most strategies to prevent it involve a physical barrier (like water) and a chemical inhibitor (such as ascorbic acid). We’ve tested several of these methods to determine which works the best.
How We Tested
To determine the best way to keep your apples, pears, and other fruits from browning, I tested four different solutions: lemon water, parsley water, honey water, and regular tap water. I also included a control group with just apple slices placed in a bowl.
I sliced up some fresh apples and placed them in each of the solutions I had prepared. After about fifteen minutes, all the slices, except for the ones in the control group (which developed brown spots), remained perfectly white with no browning. While this seemed promising, apple slices sitting in bowls of water aren’t very practical. To check how long the effects would last, I took them out of the water and left them exposed to air for about an hour.
Lemon Water
The Idea: Lemon juice offers two benefits: vitamin C (ascorbic acid) and a low pH. The oxygen in the air interacts with the vitamin C before it can react with polyphenol oxidase, which slows the browning process. Once the vitamin C is depleted, oxygen begins attacking the enzyme, causing the fruit to brown. Thankfully, if the solution is acidic enough (with a pH of around 3), the enzyme gets deactivated, and browning won’t occur.
To make this theory work, you’d typically coat the apple slices with pure lemon juice. However, doing so would make your apples taste more like lemons. The Yummy Life recommends diluting lemon juice with water (two tablespoons per cup) and soaking the apple slices in the mixture.
Results: The apple slices stayed fresh as long as they were submerged in the acidic lemon water. However, after an hour sitting on the cutting board, they were almost as brown as the control group. This suggests that using pure lemon juice or ascorbic acid powder might be more effective if you're looking to prevent browning.
Parsley Water:
The Theory: Much like lemons, parsley is rich in vitamin C, which is why it’s often used for similar purposes. However, this article from The Kitchn suggests parsley stems might outperform lemons (though, given the context, that’s not exactly setting the bar high). Unfortunately, I haven’t found anything to support why this would be true, except for the presence of ascorbic acid. Food writer Harold McGee seems to believe the water itself plays the key role, but we'll dive into that later.
Results: The apple slices remained fresh in the parsley water, though once they were exposed to air, they began to brown slightly, but nowhere near as quickly or intensely as the slices that were submerged in lemon water. It’s also worth mentioning that the slices developed a subtle parsley flavor.
Plain Water:
The Theory: As previously noted, Harold McGee posits that the lack of browning might have more to do with the water physically blocking oxygen from reaching the apple flesh, rather than any impact from the parsley stems themselves. Water physically blocking oxygen is a key point in this theory.
I've encountered many professional chefs in fine restaurants who use parsley stems to stop artichokes from turning brown. Curious, I conducted a simple experiment: I placed cut artichokes in plain water in one bowl, artichokes with crushed parsley stems in another, and on a plate. After observing the results, I found no real difference between the submerged artichokes, both of which retained their color for over an hour, much longer than the air-exposed sample. My conclusion: water alone effectively blocks oxygen, and parsley does little to improve the outcome.
Results: As predicted by Mr. McGee, when the slices were kept underwater, no browning occurred. What was more interesting, however, was that after being removed from the water, the slices browned slightly, but significantly less than those that had been in the lemon water solution.
Honey Water:
The Theory: According to a video from America’s Test Kitchen, honey contains a peptide that prevents polyphenol oxidase from triggering the browning process. ATK claims that just thirty seconds in the honey solution is enough to keep apple slices from browning for a full 24 hours. We’ve discussed this method before, and many readers have shared their success stories with it.
Results: After one hour out of the honey solution, the apple slice remained pristine. However, after three hours, a single brown spot had appeared on the slice.
Conclusions:
The honey solution emerged as the most effective method for preventing apple slices from browning, with parsley stems coming in second. (Though, the parsley stems don’t do much unless you’re looking for a faint parsley flavor in your fruits or vegetables.) Surprisingly, the plain water-soaked slices outperformed those soaked in lemon water, which ultimately had no better result than simply leaving the slices exposed to the air.
So, go ahead and use honey; your apples will stay fresh for hours (though not a full twenty-four).
