Browning in apple juice during processing and storage decreases the commercial value of product . Browning can be divided into 2 categories:enzymatic browning and non-enzymatic browning. Enzymatic browning reactions in fruits are primarily catalysed by polyphenol oxidase (PPO) in the presence of oxygen and reducing substances, while non-enzymatic browning is
the result of the Maillard reaction, which includes condensation between reducing sugars and amino acids, caramelisation, ascorbic acid degradation and pigment destruction.