Things that grow are made up of cells. All cells contain thousands of enzymes - There is an enzyme called polyphenol oxidase or tyrosinase that is present in apples, pears, potatoes, peaches, bananas, and other produce that reacts with oxygen and iron-containing phenols that are also found in the produce. When you cut the fruit or it is bruised, the fruit's cells are damaged, which allows oxygen in the air to react with the enzyme and other chemicals. This reaction basically forms a rust-colored browning on the surface of the cut portion of the fruit.
There are four ways of slowing or preventing this process and this can be done by inactivating the enzyme with heat (cooking); reducing the pH on the surface of the fruit by brushing it with the juice of any citrus fruit, such as lemon, lime, orange or grapefruit , or by soaking it in ascorbic acid; reducing the amount of available oxygen (by vacuum packing it or putting it under water; or by adding certain preservative chemicals like sulphur dioxide.
It is also known that using certain lowgrade steel knives that have some corrosion to cut the produce can increase the rate and the amount of browning by making more iron salts available for the reaction to occur.
There are four ways of slowing or preventing this process and this can be done by inactivating the enzyme with heat (cooking); reducing the pH on the surface of the fruit by brushing it with the juice of any citrus fruit, such as lemon, lime, orange or grapefruit , or by soaking it in ascorbic acid; reducing the amount of available oxygen (by vacuum packing it or putting it under water; or by adding certain preservative chemicals like sulphur dioxide.
It is also known that using certain lowgrade steel knives that have some corrosion to cut the produce can increase the rate and the amount of browning by making more iron salts available for the reaction to occur.