Why Fruits and Vegetables Turn Brown

Why Fruits and Vegetables Turn Brown | Prevent Fruits from Turning Brown | Prevent Vegetables from Turning Brown | Tips

Why Fruits and Vegetables Turn Brown

When fresh fruits and vegetables are peeled or cut open, the enzyme called polyphenol oxidase (also called tyrosinase) contained in the cells is exposed to and reacts with the oxygen in the air. The reaction that occurs, which is called oxidation, is what turns the fruits and vegetables brown. The bruising seen on some fruit, such as apples and pears, is caused by the same type of reaction. If an apple is damaged by being hit or dropped, the apple's cells in that area are damaged and the enzymes are exposed to the air inside the apple, causing them to turn brown. When preparing fruits and vegetables for use, an anti-browning solution should be used to prevent them from turning brown.

Prevent Fruits from Turning Brown

Some of the fruits that turn brown are apples, pears, peaches, and bananas. There are several techniques that can be used to prevent fruit from browning. Some of these anti-browning techniques are shown below.

Fruit
Citrus Juices Prevent browning by brushing the surface of the fruit with juice from citrus fruits, such as lemons, limes, oranges, and grapefruits. Lemon juice is often used for this purpose.
Soak in Acidulated Water Another method is to place the fruit in water that has had lemon juice or cider vinegar added to make it acidulated. The squeezed lemon can also be cut into slices and added to help acidulate the water. Juice from other citrus fruit can also be used, such as limes, oranges and grapefruit. Use approximately 1/4 cup lemon juice to 1 quart of cold water. The lemon juice in the water will help reduce the pH on the surface of the fruit and the water will reduce the amount of oxygen the fruit is exposed to. Do not over soak fruit. Do not allow fruit such as apples to soak for more than 15 minutes and bananas should soak for no more than 3 to 5 minutes. Drain and pat dry before using.
Other Options: Ascorbic acid, a commercial product, can also be added to water to create an anti-browning solution. Ascorbic acid is actually Vitamin C. Dip the slices in lemon-lime soda. Soak apples slices in apple juice until ready to use. The acidity in the apple juice prevents the apple slices from browning and doesn't change the flavor of the apple.

Prevent Fruits and Vegetables from Turning Brown

Some of the vegetables that turn brown are potatoes, sweet potatoes, parsnips, and artichokes. There are several techniques that can be used to prevent vegetables from browning. Some of these anti-browning techniques are shown below.

Vegetables
Cold Water   When the potato is completely peeled, place it in cold water immediately until ready to cook or ready to cut to desired size. The cold water will prevent the outer surface of the potato from discoloring.
Acidulated Water Create the acidulated water by adding lemon juice to cold water. Juice from other citrus fruits, such as limes, oranges, and grapefruit can also be used. Use approximately 1/4 cup lemon juice to 1 quart of cold water. Place the vegetables in the water and allow them to soak until ready to use. Vinegar can also be used in place of the lemon juice.
Other Options: Ascorbic acid, a commercial product, can also be added to water to create an anti-browning solution. Ascorbic acid is actually Vitamin C. Cook the vegetables immediately to deactivate the enzyme. This will stop the reaction from happening and turning the vegetable brown. Rub the cut surface of the vegetable with the cut edge of a lemon.

• Instead of using a commercial product containing ascorbic acid, use Vitamin C in the water for soaking fruits and vegetables. Break up and crush a 500-milligram Vitamin C tablet and dissolve in a gallon of water.
• Be sure the knife you are using to cut up fruits and vegetables does not contain any corrosion. The corrosion will cause fruits and vegetables to brown faster and will increase the amount.