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Enzymatic browning

Enzymatic browning is a chemical process involving polyphenol oxidase or other enzymes that create melanins, resulting in a brown color. Enzymatic browning is an important color reaction in fruit, vegetables, and seafood. Enzymatic browning of fruits and vegetables creates heavy economic losses for growers.

There is also non-enzymatic browning, which typically involves sugar.

Enzymatic browning is beneficial for:

• Developing flavor in tea (here the reaction is incorrectly called fermentation)
• Developing color and flavor in coffee and chocolate

Enzymatic browning is detrimental to:

• Fresh fruit and vegetables, in particular apples and potatoes
• Seafood such as shrimp

Control of browning

Enzymatic browning is usually controlled with chemicals, or by destroying the responsible chemicals with heat. Blanching to destroy the enzymes is commonly used to preserve color in vegetables. Lemon juice and other acids are used to preserve color in fruit, particularily apples, by lowering the pH and removing the copper site necessary for the enzyme to function.