enzymatic browning or melanosis is a Surface color change caused by the formation, an enzyme, a precursor of compounds that react with cellular constituents such as proteins or amino acids to form insoluble pigments of melanin type.
The enzyme responsible is the polyphenoloxidase (PPO) EC 1.14.18.1 ranked and also called tyrosinase, phenolase or cresolase. This endogenous enzyme is inactivated by cooking or freezing, but becomes active again when they thaw.
enximático browning process occurs in crustaceans, potatoes (potatoes), apple, avocado (avocado), grape juice and citrus fruits, mushrooms, among others. Anti-browning agents must meet some of the following functions:
- inhibit or compete with the PPO.
- Being reducing agents (reduce quinones and diphenols).
- Be metal chelating agents of the reaction catalyst (copper, iron).
- Reduce the absorption of oxygen.
The substances most commonly used so far been hn:
- sulfites.
- ascorbic acid.
- Citric acid and citrates.
- Phosphates acids.
New trends and research point to the use of new compounds as
- 4-hexyl resorcinol.
- Kojic Acid.
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