Factors Determining Red Fading and Discoloration in Camu‐Camu Fruit Juice

Abstract

　We investigated the factors determining color stability and discoloration in camu-camu fruit juice. Heat treatment deepened the red color of the juice, although it faded subsequently. Fading of the red color was also observed when juices were not heated. These findings suggest that the stability of red color is affected by the high concentrations of ascorbic acid in camu-camu juice. Heat treatment at high temperatures and for long durations turned the juice dark yellow. Under conditions of accelerated heating at 50℃, camu-camu juices varied from light pink to yellow and from yellow to brown. Polymerized polyphenols were more abundant in the browning juice than in light pink juice. Polyphenol oxidase activity was not detected, indicating that the browning was non-enzymatic. Regarding preservation conditions using model juices prepared from camu-camu juice containing polyphenol (PP), ascorbic acid (AA), and polyphenol and ascorbic mix (PP+AA), the b^＊ value increased in the order PP < AA < PP+AA. These findings suggest that high concentrations of ascorbic acid greatly influence non-enzymatic browning. Thus, it was clarified that red fading and browning are mainly caused by the presence of ascorbic acid in camu-camu juice.