We’ve all seen it. We cut up an apple into slices and sometimes almost immediately the apple begins to turn brown. This is due to a chemical process which occurs in fruits and vegetables called enzymatic browning. It is caused by an enzyme called polyphenol oxidase which results in brown pigments when the cells from fruits or vegetables are exposed to oxygen. Bruising on fruit is caused by the same kind of reaction. When fruit is dropped, the cells at the place of impact are damaged and exposed to oxygen inside the fruit causing it to turn brown. Enzymatic browning can also be observed in seafood such as shrimp, crab, and spiny lobster. Enzymatic browning while not harmful can just make the affected fruit or vegetable less appealing to eat. Luckily there are ways to prevent or delay the browning. Preventing enzymatic browning on fruits. Brushing the surface of fruit with the juice from citrus fruits such as lemons, limes, grapefruits and oranges, you can prevent unsightly browning. Lemon juice is often the most commonly used for this technique.
Soaking in acidulated water: Placing fruit in water that has cider vinegar or lemon juice added to it can help prevent or delay enzymatic browning. The purpose of the lemon juice or cider vinegar is to reduce the pH on the surface of the fruit while the water will help reduce the amount of oxygen that either the fruit or vegetable is exposed to. Do not allow fruits to soak for too long. Fruits such as apples and pears should soak for no more than 15 minutes and bananas no longer than 5 minutes.
Cold water: Simply by placing peeled potatoes in cold water can prevent the browning. This only works with cold water. Warm or hot water will not prevent discoloring.
Blanching: This is the process of a short heat treatment to the fruit or vegetable in order to destroy or inactivate enzymes. Blanching softens the texture, brightens the color, and has little effect on the nutrient content and flavor of the fruit or vegetable. To blanch, boil some water in a pot; add the fruit or vegetable to the boiling water; and let sit for 30 seconds. Remove the product from the hot water and place in an ice bath to cool down. The product is now blanched and ready to use.
- Freshly cut fruit is available in most dining locations on campus with a Grab-n-Go fruit cup!
- Want to precut an apple so it is ready to eat? After cutting, replace the pieces to form the original apple shape then wrap a rubber band around it to prevent it from browning! (The Rubber Band Trick | The Kitchn)
For more information on Enzymatic Browning and prevention visit:
Ricardo Blanco, Student Assistant & Hospitality Dietitian Mindy Diller, MS, RDN, LD firstname.lastname@example.org