How to keep fruit from turning brown
Keep fruit from turning brown with these tricks to maintain freshnessWhy is it that some of the tastiest fruits turn brown after you peal or bite into them? What seems like nature's way of discouraging us from eating healthy is really a chemical reaction between oxygen and certain enzymes (PPO) in the flesh. The ones that turn most brown have the highest concentration of PPO and therefore a more intense reaction.
The question isn't why it happens, but how to keep fruit from turning brown so we can enjoy our healthy snacks and keep them colorful and appealing.
Use these tricks to keep your apples, bananas and pears looking fresh for hours to days at a time.
Ever wondered how the sliced fruit in salads stays so juicy and fresh, or how moms who slice up an apple for their kid in the morning magically keep them from not turning colors by lunch time? Their secret is fresh lemon juice. Squeeze a lemon wedge or a few drips of lemon juice over your slices and mix it in well.
Once you toss apples and bananas in lemon juice, transfer to an airtight storage container and refrigerate until you're hungry.
Next to lemon juice, water is your best defense to keep fruit from turning brown. This works best for potatoes, apples and pears, but will unfortunately turn your bananas to mush.
Say you peel a batch of potatoes, but you're not yet ready to cook them. Submerging them in water prevents the PPO enzymes from oxidizing because it blocks contact with oxygen. The same goes for peeled or sliced apples. Unlike the lemon juice trick, this one is better used as a temporary fix, a few hours at most. Depending on the variety of potato of fruit, they could become water-logged if soaked too long.
Coating the exposed part of the flesh with an acidic liquid like lemon juice lowers the pH enough to stop the PPO enzymes from activating. If you don't have lemon or lime juice on hand, or want to try something a little different, soak the fruit in a bowl of Ginger ale for a few minutes. The flavor will add a little zing and keep in the moisture while preserving apple or pear slices for a few hours.
The Wonders of Blanching
"Blanching" is a fancy word for putting fruits or veggies in boiling water for about a minute and then cooling them. Doing this loosens up the skins and preserves the colors from fading or browning. For more details on blanching, check out this Serious Eats tutorial.
Basically, you bring a pot of salted water to a boil, then put your peeled or chopped fruit in. Strain the hot water after a minute and place the food in a bowl of ice water to stop it from cooking. Use a towel to pat off the water. Then store it in the fridge or pack it to-go for lunch later.
Salt is a natural preservative so it makes sense to use it to keep fruit from turning brown. The hitch is that it'll give it a slightly salty flavor. Some people think this brings out the sweetness, but others disagree. Soak one wedge in a small bowl of salt water for a few minutes, and then take a bite to see if you like it the taste.
If you're cooking with apples, note that the more sour the fruit, the more likely they are to brown fast. Apple varieties like Honey Crisps and Granny Smith brown much slower than Red Delicious.
Rinsing your slices in water before eating them will remove a lot of the salt, lemon or other flavor added by the preservative. Note that these tricks work for a few hours or days, depending on the method and the fruit.
Scientific American: Serious Eats tutorial