Enzymatic Browning Flashcards
What is Enzymatic browning?
Enzymatic browning is a chemical process that occurs when certain fruits, vegetables, or other foods are exposed to air. It’s caused by the action of enzymes, particularly polyphenol oxidase (PPO
How Enzymatic Browning Happens?
1.Cell Damage: When plant tissues (like fruits or vegetables) are cut, bruised, or otherwise damaged, the enzymes (PPO) in the cells are released.
2.Reaction with Oxygen: The PPO enzyme reacts with phenolic compounds (naturally found in many fruits and vegetables) and oxygen from the air.
3.Browning: The enzyme-phenol-oxygen reaction leads to the production of quinones, which then polymerize into brown pigments known as melanin.
Common Foods Affected by Enzymatic Browning
Apples: The most well-known example. When the flesh is exposed to air after cutting, it turns brown.
Bananas: Similar to apples, when peeled, they brown due to enzymatic activity.
Potatoes: Sliced potatoes can brown when exposed to oxygen.
Avocados: When cut, they undergo browning, affecting the texture and appeal.
Pears, Peaches, and Eggplants: All these fruits and vegetables can brown upon exposure to air.
Factors That Influence Enzymatic Browning
Oxygen: The presence of air (oxygen) is necessary for the browning process.
Temperature: Browning occurs faster at warmer temperatures.
pH: A higher pH (more alkaline) can accelerate enzymatic browning.
Time: The longer the exposure to air, the more pronounced the browning.
Prevention Methods:
- Acidification: Applying acidic substances like lemon juice or vinegar lowers the pH, inhibiting the enzyme’s activity.
- Reducing Oxygen Exposure: Using airtight containers, wrapping fruits, or applying ascorbic acid (vitamin C) can limit oxygen exposure.
3.Blanching: Briefly heating fruits or vegetables can deactivate the enzymes.
4.Refrigeration: Storing foods at lower temperatures slows down the enzymatic process.
