When you leave an apple out after cutting it, it doesn’t take very long before it begins to turn brown. Brown apples aren’t really fit for consumption, and after a while, you will need to throw them out.
Apples, pears, and bananas tend to turn brown once their inner flesh has been exposed to air. So the question is, why do apples turn brown and what can you do about it?
Why Do Apples Turn Brown?
Apples contain a large amount of an enzyme known as polyphenol oxidase. This enzyme is capable of oxidizing polyphenols. These are molecules that play a very important role in various kinds of plants, ranging from protecting them against infections and providing them with their pigmentation.
The polyphenol oxidase and the polyphenols are stored in different parts of the cells of the plant, but as soon as the cells are damaged, they become ruptured.
As a result, the enzyme comes into direct contact with the one thing that it prey on. Oxygen only serves as a catalyst and quickens the pace at which the browning effect occurs. In general, this process is known as enzymatic browning.
The problem is that it doesn’t just change the appearance of the produce, it also completely alters the nutritional value, the scent, and the flavor of the apple.
Why Does Lemon Juice Prevent Browning?
Lemon juice is acidic. Remember, the lower the amount of pH, the stronger the acid is likely to be. Lemon juice is one of the most potent acidic substances, with a pH of 2.
So, why is lemon juice such a great choice to prevent apples from becoming brown? The enzyme that is found in apples is usually “deactivated” when the acid is applied on the surface.
However, not all acids are effective when it comes to deactivating the polyphenol oxidase found in apples. Instead, the acid needs to have a pH value of less than 3 to be useful. If you use any other acid that is not as potent or under the pH value of 3, it’s not going to work.
Some also say that cranberry juice is also quite effective, because it has a pH value of less than 2. Nowadays, you can also find apples that have been genetically modified, and do not brown at all.
But, if you are against GMOs and want to make sure that you only use natural apples, you should simply squirt a bit of lemon juice on the apple slices.
This is a fantastic idea to use when you are packing lunches for your kids in the morning. Slicing up a few apples and then squirting a bit of lemon juice on them will help ensure that the apples remain fresh and ideal for consumption by the time your kids open their lunch boxes.
On the industrial scale, this method doesn’t work. Most of the solutions usually focus on reducing the amount of oxygen to prevent the oxidation reaction. This is designed to change the pH of the environment, or reduce the reaction altogether by exposing the fruit to higher or lower temperatures.
Using just a few tablespoons of lemon juice is a great way to keep apples fresh for a longer period of time. It doesn’t require a lot of effort on your part, and it also preserves the taste of the apples. After all, who doesn’t like eating apples with a bit of lemon juice or cranberry juice on them?
More importantly, you need to make sure that the concentration of the lemon juice remains adequate so that the apples remain edible. If you use highly concentrated lemon juice on your apples, it might not make them fit for consumption later on.
Some people also prefer using citric acid, although this too might make the apples unfit for eating later on.
A few people also believe that rubbing a cut lemon on sliced apples is a great way to keep them fresh. However, this is not a wise idea, because it adds a heavy lemon flavor to the apples. This dilutes the flavor of the apples themselves and you won’t enjoy eating them later on.