Brown discoloration caused by plant enzymes.
When the cells in certain fruits and vegetables
are damaged by cutting, bruising, or biting,
browning enzymes in the cell cytoplasm come
into contact with small, colorless phenolic
molecules from the storage vacuole. With the
help of oxygen from the air, the enzymes bind
the phenolic molecules together into large,
colored assemblies that turn the damaged
area brown.
Another acid that inhibits browning by
virtue of its antioxidant properties is ascorbic
acid, or vitamin C. It was first identified
around 1925 when the Hungarian biochemist
Albert Szent-Györgyi found that the juice of
some nonbrowning plants, including the
chillis grown for paprika, could delay the
discoloration of plants that do brown, and he
isolated the responsible substance.
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