Enzymatic browning reaction of apple juices prepared using a blender and a low-speed masticating household juicer.

ABSTRACT

The aim of this study was to investigate the effect of juicer type (blender or LSM household juicer) on the browning reaction of apple juice and evaluate the remaining antioxidant activity in the juice. The blender apple juice showed a darker brown color and 4.5 times higher PPO activity than LSM apple juice. This result suggested that the blender caused severer damage to plastids in cells leading to leakage of PPO into the juice than the LSM juicer. The total polyphenol and flavonoid content of LSM apple juice was approximately 2 times higher than that of blender apple juice because polyphenols and flavonoids can be used as substrates by PPO. The antioxidant activity of LSM juice was higher than that of blender juice. Together, these results suggested that the LSM juicer is superior to the blender for preparation of fresh apple juices due to the minimization of enzymatic oxidation reactions. Abbreviations LSM low-speed masticating; PPO polyphenol oxidase; ABTS 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid); DPPH 2,2-diphenyl-1-picrylhydrazyl.