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Polyphenol mediated non-enzymatic browning and its inhibition in apple juice
Zijing Xu1, Zihan Yang2, Junfu Ji2
1College of Food Science and Nutritional Engineering, National Engineering Research Centre for Fruits and Vegetables Processing, Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Engineering Research Centre for Fruits and Vegetables Processing, Ministry of Education, China Agricultural University, Beijing 10083, China.
Abstract:
Non-enzymatic browning is a severe problem in juice industry. Here, polyphenol mediated non-enzymatic browning and its inhibition in apple juice were investigated. Epicatechin (R = -0.83), catechin (CAT, R = -0.79), chlorogenic acid (CGA, R = 0.65) and caffeic acid (CAF, R = 0.65) were strongly correlated with browning. CAT and chlorogenic acid quinone (CGAQ) decreased during storage with the fastest CAT degradation rate (kCGA-enriched = 1.97 × 10-3 mg·L-1·h-1 and kCAT-enriched = 2.09 × 10-3 mg·L-1·h-1) at the initial stage, but CGA and catechin quinone (CATQ) hardly changed. It was possible that CGAQ oxidized CAT at initial stage, leading to the generation of CATQ but less browning. Then the formed CATQ reacted with CAT through the complex reactions, leading to the accumulation of yellow polymers, which might explain why browning increased faster during the secondary and tertiary stages. In addition, glutathione could effectively inhibit browning compared to ascorbic acid and oxygen blocking methods.
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