You come back from a quick trip to the copy room at work and discover that the beautiful apple you just bit into minutes ago is now brown and unappetizing. Why does this happen?
As it turns out, the moment an apple is sliced, chopped, or bitten, a biochemical reaction commonly called “enzymatic browning” begins to take place. Specifically, the enzyme known as polyphenol oxidase (PPO) oxidizes polyphenols within the flesh of the fruit. This results in new chemicals (o-quinones) that react with amino acids and produce brown-colored melanins.
But this discoloration can be avoided — somewhat.
Not all apples brown at the same rate. Different apples contain different types of enzymes and polyphenols, thus altering their rate of discoloration.
The Arctic Apple is genetically engineered to have non-browning flesh, but there are non-GMO apples that have this quality, as well. Cameo, SnowSweet, Cortland, Gala, Ambrosia, and Ginger Gold are just a few non-GMO varieties that are slow to brown. This makes them great for salads or charcuterie boards that might sit out on a counter for a while. They’re also great for snacking if you get frequently interrupted at work.
Of course, browning doesn’t impact taste. It’s just that we eat with our eyes, and after about an hour of sitting out, that brown piece of fruit definitely won’t be the apple of your eye.
In addition to apples, you might notice evidence of browning on cut avocados, eggplants, bananas, pears, and potatoes, too. The brownish-colored chemicals are pigments known as melanins, which, if you remember high school science class, give human skin its color, as well.
Interestingly, this unwanted effect on apples, is what also gives the desirable dark hue to coffee, black tea, and cocoa.
The browning phenomenon probably does have a purpose other than to ruin your lunch, though. It is thought that enzymatic browning is a form of plant defense. Some of the chemicals created by this phenomenon have been shown to ward off invading pests and pathogens.
There’s not need to stop oxidation if it never starts. Slice apples right into a bowl of water. Oxidation can’t happen if oxygen can’t reach the fruit in the first place. Of course, leaving them in water for several hours could alter the flavor, so save this method for when you’ll serve within 30 minutes.
Toss and coast apple slices with and acid like lemon or pineapple juice in a zip bag to help slow browning.
Also see, Crock pot apple cinnamon oatmeal.