Cut apples turn an unsightly shade of brown when exposed to air because of a chemical reaction. Fortunately, there are numerous ways to stop the natural phenomenon. Read on for a close look at the cause of this browning as well as handy tricks that will help you prevent it everytime.
Apples, alongside a few other fruits like pears and bananas, have a tendency to brown quickly once the skin is damaged and exposes the inner flesh to air. This reaction is simply called oxidation.
Apples contain large quantities of polyphenol oxidase, an enzyme that can oxidize polyphenols, molecules that play a variety of roles in plants, including preventing infections and giving them their pigments.
Polyphenol oxidase and the polyphenols themselves are stored in separate areas of the plant's cells, but the cells become damaged when the internal flesh of the apple is exposed through a cut or bruise. After the damage, the polyphenol oxidase comes into close contact with the substrate.
With the help of oxygen, which is in the surrounding air, the polyphenol oxidase initiates a series of chemical reactions, transforming the polyphenols and eventually producing melanins—brown pigments.
The scientific term for this process is "enzymatic browning." Although it's a natural process, the process also alters the flavor, scent, and nutritional value of the apple.
How to Prevent Browning in Apples
The easiest way to prevent browning is by:
Therefore, here's an abridged guide to preventing browning quickly:
How to Use Water, Lemon Juice, and Citric Acid to Prevent Apples From Browning
1. Water: You can prevent browning by submerging the sliced fruit in plain water, reducing its exposure to air. Simply:
2. Citrus Fruits: they contain ascorbic acid, which can lower the pH and also reverse the oxidation reaction through a process chemists call reduction. To use lemon juice and citric acid, simply:
3. Citric Acid: If you'll use citric acid, mix it with water first to make a solution to submerge the apples in. Rubbing the powder onto the surface of the cut apples impacts the flavor of the apples.